--- name: "echo" section: "3tclx" platform: "linux" package: "tclX" version: "7.4a-p2-1" release: "Debian 1.1 (Buzz)" platforms: ["linux"] url: "https://new.carta.tech/TclX" --- # echo(3tclx) Extended Tcl: Extended command set for Tcl Part of [TclX(3tclx)](/TclX/3tclx.md). ## NAME TclX - Extended Tcl: Extended command set for Tcl ## INTRODUCTION This man page contains the documentation for all of the extensions that are added to Tcl 7.4 by Extended Tcl (TclX 7.4a). These extensions provide extend Tcl's capabilities by adding new commands to it, without changing the syntax of standard Tcl. Extended Tcl is a superset of standard Tcl and is built alongside the standard Tcl sources. Extended Tcl has three basic functional areas: A set of new commands, a Tcl shell (i.e. a Unix shell-style command line and interactive environment), and a user-extensible library of useful Tcl procedures, any of which can be automatically loaded on the first attempt to execute it. The command descriptions are separated into several sections: - o General Commands - o Debugging and Development Commands - o Unix Access Commands - o File Commands - o TCP/IP Server Access - o File Scanning Commands - o Math Commands - o List Maninipulation Commands - o Keyed Lists - o String and Character Manipulation Commands - o XPG/3 Message Catalog Commands - o Extended Tcl Shell - o Help Facility - o Tcl Loadable Libraries and Packages ## GENERAL COMMANDS A set of general, useful Tcl commands, includes a command to begin an interactive session with Tcl, a facility for tracing execution, and a looping command. - **dirs** This procedure lists the directories in the directory stack. - **commandloop ?*prompt1*? ?*prompt2*?** Create an interactive command loop for the current TCL interpreter. This command receives commands from stdin and executes them. It is useful TCL scripts that do not normally converse interactively with a user through a Tcl command interpreter, but which sometimes want to enter this mode. *Prompt1* is a Tcl command that is evaluated to output a prompt string. The old value of **tcl\_prompt1** is saved and it is set to this value for the duration of the command loop. *Prompt2* is a command that is evaluated to output the \`\`downlevel prompt'', which is the prompt which is issued for continuation input. The old value of **tcl\_prompt2** is saved and it is set to this value for the duration of the command loop. When the command terminates, the variables for the prompt hooks will be set to their old value. If these arguments are not specified, the prompt hooks use their current value. - **echo ?*str ...*?** Writes zero or more strings to standard output, followed by a newline. - **infox *option*** Return information about Extended Tcl, or the current application. The following **infox** command options are available: - **version** Return the version number of Extended Tcl. The version number for Extended Tcl is generated by combining the base version of the standard Tcl code with a letter indicating the version of Extended Tcl being used. This is the documentation for version **7.4a**. - **patchlevel** Return the patchlevel for Extended Tcl. - **have\_fchown** Return **1** if the **fchown** system call is available. This supports the **-fileid** option on the **chown** and **chgrp** commands. - **have\_fchmod** Return **1** if the **fchmod** system call is available. This supports the **-fileid** option on the **chmod** command. - **have\_flock** Return **1** if the **flock** command defined, **0** if it is not available. - **have\_fsync** Return **1** if the **fsync** system call is available and the **sync** command will sync individual files. **0** if it is not available and the **sync** command will always sync all file buffers. - **have\_ftruncate** Return **1** if the **ftruncate** or **chsize** system call is available. If it is, the **ftruncate** command **-fileid** option maybe used. - **have\_msgcats** Return **1** if XPG message catalogs are available, **0** if they are not. The **catgets** is designed to continue to function without message catalogs, always returning the default string. - **have\_posix\_signals** Return **1** if Posix signals are available (**block** and **unblock** options available for the signal command). **0** is returned if Posix signals are not available. - **have\_sockets** Return **1** if sockets are available (**server\_\*** suite and **fstat** **localhost** and **remotehost** options). **0** is returned if sockets are not available. - **have\_truncate** Return **1** if the **truncate** system call is available. If it is, the **ftruncate** command may truncate by file path. - **appname** Return the symbolic application name of the current application linked with the Extended Tcl library. The C variable **tclAppName** must be set by the application to return an application specific value for this variable. - **applongname** Return a natural language name for the current application. The C variable **tclLongAppName** must be set by the application to return an application specific value for this variable. - **appversion** Return the version number for the current application. The C variable **tclAppVersion** must be set by the application to return an application-specific value for this variable. - **apppatchlevel** Return the patchlevel for the current application. The C variable **tclAppPatchlevel** must be set by the application to return an application-specific value for this variable. - **for\_array\_keys *var array\_name code*** This procedure performs a foreach-style loop for each key in the named array. The **break** and **continue** statements work as with **foreach**. - **for\_recursive\_glob *var dirlist globlist code*** This procedure performs a foreach-style loop over recursively matched files. All directories in *dirlist* are recursively searched (breadth-first), comparing each file found against the file glob patterns in **globlist**. For each matched file, the variable *var* is set to the file path and *code* is evaluated. Symbolic links are not followed. - **loop *var first limit ?increment? body*** **Loop** is a looping command, similar in behavior to the Tcl **for** statement, except that the **loop** statement achieves substantially higher performance and is easier to code when the beginning and ending values of a loop are known, and the loop variable is to be incremented by a known, fixed amount every time through the loop. The *var* argument is the name of a Tcl variable that will contain the loop index. The loop index is set to the value specified by *first*. The Tcl interpreter is invoked upon *body* zero or more times, where *var* is incremented by *increment* every time through the loop, or by one if *increment* is not specified. *Increment* can be negative in which case the loop will count downwards. When *var* reaches *limit*, the loop terminates without a subsequent execution of *body*. For instance, if the original **loop** parameters would cause **loop** to terminate, say *first* was one, *limit* was zero and *increment* was not specified or was non-negative, *body* is not executed at all and **loop** returns. The *first*, *limit* and *increment* are integer expressions. They are only evaulated once at the beginning of the loop. If a **continue** command is invoked within *body* then any remaining commands in the current execution of *body* are skipped, as in the **for** command. If a **break** command is invoked within *body* then the **loop** command will return immediately. **Loop** returns an empty string. - **popd** This procedure pops the top directory entry from the directory stack and make it the current directory. - **pushd ?*dir*?** This procedure pushs the current directory onto the directory stack and **cd** to the specified directory. If the directory is not specified, then the current directory is pushed, but remains unchanged. - **recursive\_glob *dirlist globlist*** This procedure returns a list of recursively matches files. All directories in *dirlist* are recursively searched (breadth-first), comparing each file found against the file glob patterns in **globlist**. Symbolic links are not followed. - **showproc *?procname ...?*** This procedure lists the definition of the named procedures. Loading them if it is not already loaded. If no procedure names are supplied, the definitions of all currently loaded procedures are returned. - This section contains information on commands and procdures that are ## DEBUGGING AND DEVELOPMENT COMMANDS useful for developing and debugging Tcl scripts. - **cmdtrace *level*\|on ?noeval? ?notruncate? ?*procs*? ?*fileid*? ?command *cmd*?** Print a trace statement for all commands executed at depth of *level* or below (1 is the top level). If **on** is specified, all commands at any level are traced. The following options are available: - **noeval** Causes arguments to be printed unevaluated. If **noeval** is specified, the arguments are printed before evaluation. Otherwise, they are printed afterwards. If the command line is longer than 60 characters, it is truncated to 60 and a "..." is postpended to indicate that there was more output than was displayed. If an evaluated argument contains a space, the entire argument will be enclosed inside of braces (\`{}') to allow the reader to visually separate the arguments from each other. - **notruncate** Disables the truncation of commands and evaluated arguments. - **procs** Enables the tracing of procedure calls only. Commands that aren't procedure calls (i.e. calls to commands that are written in C, C++ or some object-compatible language) are not traced if the **procs** option is specified. This option is particularly useful for greatly reducing the output of **cmdtrace** while debugging. - **fileid** This is a file id as returned by the **open** command. If specified, then the trace output will be written to the file rather than stdout. A stdio buffer flush is done after every line is written so that the trace may be monitored externally or provide useful information for debugging problems that cause core dumps. - **command *cmd*** Call the specified command *cmd* on when each command is executed instead of tracing to a file. See the description of the functionally below. This option may not be specified with a **fileid**. The most common use of this command is to enable tracing to a file during the development. If a failure occurs, a trace is then available when needed. Command tracing will slow down the execution of code, so it should be removed when code is debugged. The following command will enable tracing to a file for the remainder of the program: - cmdtrace on \[open cmd.log w\] The **command** option causes a user specified trace command to be called for each command executed. The command will have the following arguments appended to it before evaluation: - 1\) *command* -A string containing the text of the command, before any argument substitution. - 2\) *argv* - A list of the final argument information that will be passed to the command after command, variable, and backslash substitution. - 3\) *evalLevel* - The **Tcl\_Eval** call level. - 4\) *procLevel* - The procedure call level. The command should be constructed in such a manner that it will work if additional arguments are added in the future. It is suggested that the command be a **proc** with the final argument being **args**. Tracing will be turned off while the command is being executed. The values of the **errorInfo** and **errorCode** variables will be saved and restored on return from the command. It is the command's responsibility to preserve all other state. If an error occurs during the execution of **command**, an error message is dumped to stderr and the tracing is disabled. The underlying mechanism that this functionality is built on does not support returning an error to the interpreter. - **cmdtrace off** Turn off all tracing. - **cmdtrace depth** Returns the current maximum trace level, or zero if trace is disabled. - **edprocs ?*proc*...?** This procedure writes the named procedures, or all currently defined procedures, to a temporary file, then calls an editor on it (as specified by the **EDITOR** environment variable, or **vi** if none is specified), then sources the file back in if it was changed. - **profile ?-commands? on** - **profile off *arrayVar*** This command is used to collect a performance profile of a Tcl script. It collects data at the Tcl procedure level. The number of calls to a procedure, and the amount of real and CPU time is collected. Time is also collected for the global context. The procedure data is collected by bucketing it based on the procedure call stack, this allows determination of how much time is spent in a particular procedure in each of it's calling contexts. The **on** option enables profile data collection. If the **-commands** option is specifed, data on all commands within a procedure is collected as well a procedures. Multiple occurrences of a command within a procedure are not distinguished, but this data may still be useful for analysis. The **off** option turns off profiling and moves the data collected to the array *arrayVar*. The array is address by a list containing the procedure call stack. Element zero is the top of the stack, the procedure that the data is for. The data in each entry is a list consisting of the procedure call count and the real time and CPU time in milliseconds spent in the procedure (and all procedures it called). The list is in the form {*count* *real cpu*}. A Tcl procedure **profrep** is supplied for reducing the data and producing a report - **profrep *profDataVar sortKey* ?*outFile*? ?*userTitle*?** This procedure generates a report from data collect from the profile command. **ProfDataVar** is the name of the array containing the data returned by the **profile** command. **SortKey** indicates which data value to sort by. It should be one of "**calls**", "**cpu**" or "**real**". **OutFile** is the name of file to write the report to. If omitted, stdout is assumed. **UserTitle** is an optional title line to add to output. - **saveprocs *fileName* ?*proc*...?** This prodcure saves the definition of the named procedure, or all currently defined procedures if none is specified, to the named file. ## UNIX ACCESS COMMANDS These commands provide access to many basic Unix facilities, including process handling, date and time processing, signal handling and the executing commands via the shell. - **alarm *seconds*** Instructs the system to send a SIGALRM signal in the specified number of seconds. This is a floating point number, so fractions of a section may be specified. If *seconds* is 0.0, any previous alarm request is canceled. Only one alarm at a time may be active; the command returns the number of seconds left in the previous alarm. On systems without the **setitimer** system call, *seconds* is rounded up to an integer number of seconds. - **convertclock *dateString* ?GMT\|{}? ?*baseClock*?** Convert *dateString* to an integer clock value (see **getclock**). This command can parse and convert virtually any standard date and/or time string, which can include standard time zone mnemonics. If only a time is specified, the current date is assumed. If the string does not contain a time zone mnemonic, the local time zone is assumed, unless the **GMT** argument is specified, in which case the clock value is calculated assuming that the specified time is relative to Greenwich Mean Time. If *baseClock* is specified, it should contain an integer clock value. Only the date in this value is used, not the time. This is useful for determining the time on a specific day or doing other date-relative conversions. The character string consists of zero or more specifications of the following form: *time* - A time of day, which is of the form *hh*\[*:mm*\[*:ss*\]\] \[*meridian*\] \[*zone*\] or *hhmm* \[*meridian*\] \[*zone*\]. If no meridian is specified, *hh* is interpreted on a 24-hour clock. *date* - A specific month and day with optional year. The acceptable formats are *mm/dd*\[*/yy*\], *monthname dd*\[, *yy*\], *dd monthname* \[*yy*\], and *day, dd monthname yy*. The default year is the current year. If the year is less then 100, then 1900 is added to it. *relative time* - A specification relative to the current time. The format is *number unit*; acceptable units are *year*, *fortnight*, *month*, *week*, *day*, *hour*, *minute* (or *min*), and *second* (or *sec*). The unit can be specified as a singular or plural, as in *3 weeks*. These modifiers may also be specified: *tomorrow*, *yesterday*, *today*, *now*, *last*, *this*, *next*, *ago.* The actual date is calculated according to the following steps. First, any absolute date and/or time is processed and converted. Using that time as the base, day-of-week specifications are added. Next, relative specifications are used. If a date or day is specified, and no absolute or relative time is given, midnight is used. Finally, a correction is applied so that the correct hour of the day is produced after allowing for daylight savings time differences. *convertclock* ignores case when parsing all words. The names of the months and days of the week can be abbreviated to their first three letters, with optional trailing period. Periods are ignored in any timezone or meridian values. Note that *convertclock* will convert symbolic time-zone names, but these are not standardized and there are conflicts with various parts of the world. Use GMT when trying to produce a portable time that can then be converted back to a numeric value. The only dates in the range 1902 and 2037 may be converted. Some examples are: ``` convertclock "14 Feb 92" convertclock "Feb 14, 1992 12:20 PM PST" convertclock "12:20 PM Feb 14, 1992" ``` - **execl ?-argv0 argv0? *prog* ?*arglist*?** Do an execl, replacing the current program (either Extended Tcl or an application with Extended Tcl embedded into it) with *prog* and passing the arguments in the list *arglist*. The **-argv0** options specifies that *argv0* is to be passed to the program as argv \[0\] rather than *prog*. Note: If you are using **execl** in a Tk application and it fails, you may not do anything that accesses the X server or you will receive a **BadWindow** error from the X server. This includes executing the Tk version of the **exit** command. We suggest using the following command to abort Tk applications after an **execl** failure: ``` kill [id process] ``` - **fmtclock *clockval* ?*format*? ?GMT\|{}?** Converts a Unix integer time value, typically returned by **getclock**, **convertclock**, or the **atime**, **mtime**, or **ctime** options of the **file** command, to human-readable form. The *format* argument is a string that describes how the date and time are to be formatted. Field descriptors consist of a \`\`%'' followed by a field descriptor character. All other characters are copied into the result. Valid field descriptors are: ``` %% - Insert a %. %a - Abbreviated weekday name. %A - Full weekday name %b - Abbreviated month name. %B - Full month name. %d - Day of month (01 - 31). %D - Date as %m/%d/%y. %e - Day of month (1-31), no leading zeros. %h - Abbreviated month name. %H - Hour (00 - 23). %I - Hour (00 - 12). %j - Day number of year (001 - 366). %m - Month number (01 - 12). %M - Minute (00 - 59). %n - Insert a new line. %p - AM or PM. %r - Time as %I:%M:%S %p. %R - Time as %H:%M. %S - Seconds (00 - 59). %t - Insert a tab. %T - Time as %H:%M:%S. %U - Week number of year (01 - 52), Sunday is the first day of the week. %w - Weekday number (Sunday = 0). %W - Week number of year (01 - 52), Monday is the first day of the week. %x - Local specific date format. %X - Local specific time format. %y - Year within century (00 - 99). %Y - Year as ccyy (e.g. 1990) %Z - Time zone name. ``` If format is not specified, "%a %b %d %H:%M:%S %Z %Y" is used. If **GMT** is specified, the time will be formated as Greenwich Mean Time. If the argument is not specified or is empty, then the local timezone will be used as defined by the operating environment. - **chroot *dirname*** Change root directory to *dirname*, by invoking the POSIX **[chroot(2)](/chroot/2.md)** system call. This command only succeeds if running as root. - **fork** Fork the current Tcl process. Fork returns zero to the child process and the process number of the child to the parent process. If the fork fails, a Tcl error is generated. If an **execl** is not going to be performed before the child process does output, or if a **close** and **dup** sequence is going to be performed on **stdout** or **stderr**, then a **flush** should be issued against **stdout**, **stderr** and any other open output file before doing the **fork**. Otherwise characters from the parent process pending in the buffers will be output by both the parent and child processes. Note: If you are **fork**ing in a Tk based apllication you must **execl** before doing any window operations in the child or you will receive a **BadWindow** error from the X server. - **getclock** Return the current date and time as a system-dependent integer value. The unit of the value is seconds, allowing it to be used for relative time calculations. - **id options** This command provides a means of getting, setting and converting user, group and process ids. The **id** command has the following options: - **id user ?*name*?** - **id userid ?*uid*?** Set the real and effective user ID to *name* or *uid*, if the name (or uid) is valid and permissions allow it. If the name (or uid) is not specified, the current name (or uid) is returned. - **id convert userid *uid*** - **id convert user *name*** Convert a user ID number to a user name, or vice versa. - **id group ?*name*?** - **id groupid ?*gid*?** Set the real and effective group ID to *name* or *gid*, if the name (or gid) is valid and permissions allow it. If the group name (or gid) is not specified, the current group name (or gid) is returned. - **id groups** - **id groupids** Return the current group access list of the process. The option **groups** returns group names and **groupids** returns id numbers. - **id convert groupid *gid*** - **id convert group *name*** Convert a group ID number to a group name, or vice versa. - **id effective user** - **id effective userid** Return the effective user name, or effective user ID number, respectively. - **id effective group** - **id effective groupid** Return the effective group name, or effective group ID number, respectively. - **id effective groupids** Return all of the groupids the user is a member of. - **id host** Return the hostname of the system the program is running on. - **id process** Return the process ID of the current process. - **id process parent** Return the process ID of the parent of the current process. - **id process group** Return the process group ID of the current process. - **id process group set** Set the process group ID of the current process to its process ID. - **id host** Returns the standard host name of the machine the process is executing on. - **kill ?-pgroup ?*signal*? *idlist*** Send a signal to the each process in the list *idlist*, if permitted. *Signal*, if present, is the signal number or the symbolic name of the signal, see the signal system call manual page. The leading \`\`SIG'' is optional when the signal is specified by its symbolic name. The default for *signo* is 15, SIGTERM. If **-pgroup** is specified, the numbers in *idlist* are take as process group ids and the signal is sent to all of the process in that process group. A process group id of **0** specifies the current process group. - **link ?-sym? *srcpath destpath*** Create a directory entry, *destpath*, linking it to the existing file, *srcpath*. If **-sym** is specified, a symbolic link, rather than a hard link, is created. (The **-sym** option is only available on systems that support symbolic links.) - **mkdir ?-path? *dirList*** Create each of the directories in the list *dirList*. The mode on the new directories is 777, modified by the umask. If **-path** is specified, then any non-existent parent directories in the specified path(s) are also created. - **nice ?*priorityincr*?** Change or return the process priority. If *priorityincr* is omitted, the current priority is returned. If *priorityincr* is positive, it is added to the current *priority* level, up to a system defined maximum (normally **19**), Negative *priorityincr* values cumulatively increase the program's priority down to a system defined minimum (normally **-19**); increasing priority with negative niceness values will only work for the superuser. The new priority is returned. - **readdir *dirPath*** Returns a list containing the contents of the directory *dirPath*. The directory entries "." and ".." are not returned. - **rmdir ?-nocomplain? *dirList*** Remove each of the directories in the list *dirList*. If **-nocomplain** is specified, then errors will be ignored. - **signal *action* *siglist* ?*command*?** Specify the action to take when a Unix signal is received by Extended Tcl, or a program that embeds it. *Siglist* is a list of either the symbolic or numeric Unix signal (the SIG prefix is optional). *Action* is one of the following actions to be performed on receipt of the signal. To specify all modifiable signals, use \`\*' (this will not include SIGKILL and SIGSTOP, as they can not be modified). - **default** - Perform system default action when signal is received (see **signal** system call documentation). - **ignore** - Ignore the signal. - **error** - Generate a catchable Tcl error. It will be as if the command that was running returned an error. The error code will be in the form:\ \ **POSIX SIG** *signame*\ For the death of child signal, *signame* will always be SIGCHLD, rather than SIGCLD, to allow writing portable code. - **trap** - When the signal occurs, execute *command* and continue execution if an error is not returned by *command*. The command will be executed in the global context. The command will be edited before execution, replacing occurrences of "%S" with the signal name. Occurrences of "%%" result in a single "%". This editing occurs just before the trap command is evaluated. If an error is returned, then follow the standard Tcl error mechanism. Often *command* will just do an **exit**. - **get** - Retrieve the current settings of the specified signals. A keyed list will be returned were the keys are one of the specified signals and the values are a list cosisting of the action associated with the signal, a **0** if the signal may be delivered (not block) and a **1** if it is blocked. The actions maybe one of \`**default**',\`**ignore**', \`**error**' or \`**trap**. If the action is trap, the third element is the command associated with the action. The action \`**unknown**' is returned if a non-Tcl signal handler has been associated with the signal. - **set** - Set signals from a keyed list in the format returned by the **get**. For this action, *siglist* is the keyed list of signal state. Signals with an action of \`**unknown**' are not modified. - **block** - Block the specified signals from being received. (Posix systems only). - **unblock** - Allow the specified signal to be received. Pending signals will not occur. (Posix systems only). The signal action will remain enabled after the specified signal has occurred. The exception to this is **SIGCHLD** on systems without Posix signals. For these systems, **SIGCHLD** is not be automatically reenabled. After a **SIGCHLD** signal is received, a call to **wait** must be performed to retrieve the exit status of the child process before issuing another **signal SIGCHLD** *...* command. For code that is to be portable between both types of systems, use this approach. Signals are not processed until after the completion of the Tcl command that is executing when the signal is received. If an interactive Tcl shell is running, then the **SIGINT** will be set to **error**, non-interactive Tcl sessions leave **SIGINT** unchanged from when the process started (normally **default** for foreground processes and **ignore** for processes in the background). - **sleep *seconds*** Sleep the Extended Tcl process for *seconds* seconds. - **system *command*** Executes *command* via the [*system*(3)](/system/3.md) call. Differs from **exec** in that **system** doesn't return the executed command's standard output as the result string, and **system** goes through the Unix shell to provide wildcard expansion, redirection, etc, as is normal from an **sh** command line. The exit code of the command is returned. - **sync ?*fileId*?** If *fileId* is not specified, or if it is and this system does not support the *fsync* system call, issues a *sync* system call to flush all pending disk output. If *fileId* is specified and the system does support the *fsync* system call, issues an *fsync* on the file corresponding to the specified Tcl *fileId* to force all pending output to that file out to the disk. If *fileId* is specified, the file must be writable. A **flush** will be issued against the *fileId* before the sync. The *infox have\_fsync* command can be used to determine if "**sync** *fileId*" will do a *sync* or a *fsync*. - **times** Return a list containing the process and child execution times in the form:\ \ *utime stime cutime cstime*\ Also see the [*times*(2)](/times/2.md) system call manual page. The values are in milliseconds. - **umask ?*octalmask*?** Sets file-creation mode mask to the octal value of *octalmask*. If *octalmask* is omitted, the current mask is returned. - **unlink ?-nocomplain? *filelist*** Delete (unlink) the files whose names are in the list *filelist*. If **-nocomplain** is specified, then errors will be ignored. - **wait ?-nohang? ?-untraced? ?-pgroup? ?*pid*?** Waits for a process created with the **execl** command to terminate, either due to an untrapped signal or call to *exit* system call. If the process id *pid* is specified, they wait on that process, otherwise wait on any child process to terminate. If **-nohang** is specified, then don't block waiting on a process to terminate. If no process is immediately available, return an empty list. If **-untraced** is specified then the status of child processes that are stopped, and whose status has not yet been reported since they stopped, are also returned. If **-pgroup** is specfied and *pid* is not specified, then wait on any child process whose process groupd ID is they same as the calling process. If *pid* is specified with **-pgroup**, then it is take as a process group ID, waiting on any process in that process group to terminate. **Wait** returns a list containing three elements: The first element is the process id of the process that terminated. If the process exited normally, the second element is \`EXIT', and the third contains the numeric exit code. If the process terminated due to a signal, the second element is \`SIG', and the third contains the signal name. If the process is currently stopped (on systems that support SIGSTP), the second element is \`STOP', followed by the signal name. Note that it is possible to wait on processes to terminate that were create in the background with the **exec** command. However, if any other **exec** command is executed after the process terminates, then the process status will be reaped by the **exec** command and will not be available to the **wait** command. ## FILE COMMANDS These commands provide extended file access and manipulation. This includes searching ASCII-sorted data files, copying files, duplicating file descriptors, control of file access options, retrieving open file status, and creating pipes with the **pipe** system call. Also linking and unlinking files, setting file, process, and user attributes and truncating files. An interface to the **select** system call is available on Unix systems that support it. It should be noted that Tcl file I/O is implemented on top of the stdio library. By default, the file is buffered. When communicating to a process through a pipe, a **flush** command should be issued to force the data out. Alternatively, the **fcntl** command may be used to set the buffering mode of a file to line-buffered or unbuffered. - **bsearch *fileId key* ?*retvar*? ?*compare\_proc*?** Search an opened file *fileId* containing lines of text sorted into ascending order for a match. *Key* contains the string to match. If *retvar* is specified, then the line from the file is returned in *retvar*, and the command returns **1** if *key* was found, and **0** if it wasn't. If *retvar* is not specified or is a null name, then the command returns the line that was found, or an empty string if *key* wasn't found. By default, the key is matched against the first white-space separated field in each line. The field is treated as an ASCII string. If *compare\_proc* is specified, then it defines the name of a Tcl procedure to evaluate against each line read from the sorted file during the execution of the **bsearch** command. *Compare\_proc* takes two arguments, the key and a line extracted from the file. The compare routine should return a number less than zero if the key is less than the line, zero if the key matches the line, or greater than zero if the key is greater than the line. The file must be sorted in ascending order according to the same criteria *compare\_proc* uses to compare the key with the line, or errouenous results will occur. - **copyfile ?-bytes *num*\|-maxbytes *num*? *fromFileId toFileId*** Copies the rest of the file specified by *fromFileId*, starting from its current position, to the file specified by *toFileId*, starting from its current position. If **-bytes** is specified, then *num* bytes are copied. If less than *num* bytes are available, an error is returned. If **-maxbytes** is specified, then *num* bytes are copied but no error is returned if less are available. The command returns the number of bytes that were copied. The **-bytes** option is particularly useful for mixing binary data in with ASCII commands or data in a data stream. - **chmod \[-fileid\] *mode* *filelist*** Set permissions of each of the files in the list *filelist* to *mode*, where *mode* is an absolute numeric mode or symbolic permissions as in the UNIX **[chmod(1)](/chmod/1.md)** command. To specify a mode as octal, it should be prefixed with a "0" (e.g. 0622). If the option **-fileid** is specified, *filelist* is a list of open file identifiers rather than a list of file names. This option is not available on all Unix systems. Use the **infox have\_fchmod** command to determine if this functionallity is available. - **chown \[-fileid\] *owner*\|{*owner group*} *filelist*** Set owner of each file in the list *filelist* to *owner*, which can be a user name or numeric user id. If the first parameter is a list, then the owner is set to the first element of the list and the group is set to the second element. *Group* can be a group name or numeric group id. If *group* is {}, then the file group will be set to the login group of the specified user. If the option **-fileid** is specified, *filelist* is a list of open file identifiers rather than a list of file names. This option is not available on all Unix systems. Use the **infox have\_fchown** command to determine if this functionallity is available. - **chgrp \[-fileid\] *group* *filelist*** Set the group id of each file in the list *filelist* to *group*, which can be either a group name or a numeric group id. If the option **-fileid** is specified, *filelist* is a list of open file identifiers rather than a list of file names. This option is not available on all Unix systems. Use the **infox have\_fchown** command to determine if this functionallity is available. - **dup *fileId* ?*targetFileId*?** Duplicate an open file. A new file id is opened that addresses the same file as *fileId*. If *targetFileId* is specified, the the file is dup to this specified file id. Normally this is **stdin**, **stdout**, or **stderr**. The dup command will handle flushing output and closing this file. The new file will be buffered, if its needs to be unbuffered, use the **fcntl** command to set it unbuffered. If *fileId* is a number rather than a Tcl file id, then the **dup** command will bind that file to a Tcl file id. This is usedful for accessing files that are passed from the parent process. The argument ?*targetFileId*? is not valid with this operation. - **fcntl *fileId* *attribute ?value*?** This command either sets or clears a file option or returns its current value. If *value* are not specified, then the current value of **attribute** is returned. The following attributes may be specified: - **RDONLY** - The file is opened for reading only. (Get only) **WRONLY** - The file is opened for writing only. (Get only) **RDWR** - The file is opened for reading and writing. (Get only) **READ** - If the file is readable. (Get only). **WRITE** - If the file is writable. (Get only). **APPEND** - The file is opened for append-only writes. All writes will be forced to the end of the file. **NONBLOCK** - The file is to be accessed with non-blocking I/O. See the **read** system call for a description of how it affects the behavior of file reads. **CLOEXEC** - Close the file on an process exec. If the **execl** command or some other mechanism causes the process to do an exec, the file will be closed if this option is set. **NOBUF** - The file is not buffered. If set, then there no stdio buffering for the file. **LINEBUF** - Output the file will be line buffered. The buffer will be flushed when a newline is written, when the buffer is full, or when input is requested. The **APPEND**, **NONBLOCK**, and **CLOEXEC** attributes may be set or cleared by specifying the attribute name and a value **1** to set the attribute and **0** to clear it. The **NOBUF** and **LINEBUF** attributes may only be set (a value of **1**) and only one of the options may be selected. Once set, it may not be changed. These options should be set before any I/O operations have been done on the file or data may be lost. - **flock *options fileId* ?*start*? ?*length*? ?*origin*?** This command places a lock on all or part of the file specified by *fileId*. The lock is either advisory or mandatory, depending on the mode bits of the file. The lock is placed beginning at relative byte offset *start* for *length* bytes. If *start* or *length* is omitted or empty, zero is assumed. If *length* is zero, then the lock always extents to end of file, even if the file grows. If *origin* is "**start**", then the offset is relative to the beginning of the file. If it is "**current**", it is relative to the current access position in the file. If it is "**end**", then it is relative to the end-of-file (a negative is before the EOF, positive is after). If *origin* is omitted, **start** is assumed. The following *options* are recognized: - **-read** - Place a read lock on the file. Multiple processes may be accessing the file with read-locks. - **-write** - Place a write lock on the file. Only one process may be accessing a file if there is a write lock. - **-nowait** - If specified, then the process will not block if the lock can not be obtained. With this option, the command returns 1 if the lock is obtained and 0 if it is not. See your system's **fcntl** system call documentation for full details of the behavior of file locking. If locking is being done on ranges of a file, it is best to use unbuffered file access (see the **fcntl** command). - **for\_file *var filename { code }*** This procedure implements a loop over the contents of a file. For each line in *filename*, it sets *var* to the line and executes *code*. The **break** and **continue** commands work as with foreach. For example, the command ``` for_file line /etc/passwd {echo $line} ``` would echo all the lines in the password file. - **funlock *fileId* ?*start*? ?*length*? ?*origin*?** Remove a locked from a file that was previously placed with the *flock* command. The arguments are the same as for the *flock* command, see that command for more details. - **fstat *fileId* ?*item*?\|?stat *arrayvar*?** Obtain status information about an open file. The following keys are used to identify data items:\ - o **atime** - The time of last access. - o **ctime** - The time of last file status change - o **dev** - The device containing a directory for the file. This value uniquely identifies the file system that contains the file. - o **gid** - The group ID of the file's group. - o **ino** - The inode number. This field uniquely identifies the file in a given file system. - o **mode** - The mode of the file (see the **mknod** system call). - o **mtime** - Time when the data in the file was last modified. - o **nlink** - The number of links to the file. - o **size** - The file size in bytes. - o **tty** - If the file is associated with a terminal, then 1 otherwise 0. - o **type** - The type of the file in symbolic form, which is one of the following values: **file**, **directory**, **characterSpecial**, **blockSpecial**, **fifo**, **link**, or **socket**. - o **uid** - The user ID of the file's owner. If one of these keys is specified as *item*, then that data item is returned. If **stat** *arrayvar* is specified, then the information is returned in the array *arrrayvar*. Each of the above keys indexes an element of the array containing the data. If only *fileId* is specified, the command returns the data as a keyed list. The following values may be returned only if explicitly asked for, it will not be returned with the array or keyed list forms: - o **remotehost** - If *fileId* is a TCP/IP socket connection, then a list is returned with the first element being the remote host IP address. If the remote host name can be found, it is returned as the second element of the list. The remote host IP port number is returned as the this element. - o **localhost** - If *fileId* is a TCP/IP socket connection, then a list is returned with the first element being the local host IP address. If the local host name can be found, it is returned as the second element of the list. The local host IP port number is returned as the this element. - **ftruncate \[-fileid\] *file newsize*** Truncate a file to have a length of at most *newsize* bytes. If the option **-fileid** is specified, *file* is an open file identifier, otherwise it is a file path. This command is not available or not fully functional if the underlying operating system support is not available. The command **infox have\_truncate** will indicate if this command may truncate by file path. The command **infox have\_ftruncate** will indicate if this command may truncate by file id. - **lgets *fileId* ?*varName*?** Reads the next Tcl list from the file given by *fileId* and discards the terminating newline character. This command differs from the **gets** command, in that it reads Tcl lists rather than lines. If the list contains a newline, then that newline will be returned as part of the result. Only a newline not quoted as part of the list indicates the end of the list. There is no corresponding command for outputing lists, as **puts** will do this correctly. If *varName* is specified, then the line is placed in the variable by that name and the return value is a count of the number of characters read (not including the newline). If the end of the file is reached before reading any characters then -1 is returned and *varName* is set to an empty string. If *varName* is not specified then the return value will be the line (minus the newline character) or an empty string if the end of the file is reached before reading any characters. An empty string will also be returned if a line contains no characters except the newline, so **eof** may have to be used to determine what really happened. - **frename *oldPath newPath*** Renames *oldPath* to *newPath*. This command does not support renaming across file systems. - **pipe ?*fileId\_var\_r fileId\_var\_w*?** Create a pipe. If *fileId\_var\_r* and *fileId\_var\_r* are specified, then **pipe** will set the a variable named *fileId\_var\_r* to contain the fileId of the side of the pipe that was opened for reading, and *fileId\_var\_w* will contain the fileId of the side of the pipe that was opened for writing. If the fileId variables are not specified, then a list containing the read and write fileIdw is returned as the result of the command. - **read\_file ?-nonewline? *fileName*** **read\_file *fileName* *numBytes***\ This proecure reads the file *fileName* and returns the contents as a string. If **-nonewline** is specified, then the last character of the file is discarded if it is a newline. The second form specifies exactly how many bytes will be read and returned, unless there are fewer than *numBytes* bytes left in the file; in this case, all the remaining bytes are returned. - **select *readfileIds* ?*writefileIds*? ?*exceptfileIds*? ?*timeout*?** This command allows an Extended Tcl program to wait on zero or more files being ready for for reading, writing, have an exceptional condition pending, or for a timeout period to expire. *readFileIds*, *writeFileIds*, *exceptFileIds* are each lists of fileIds, as returned from **open**, to query. An empty list ({}) may be specified if a category is not used. The files specified by the *readFileIds* list are checked to see if data is available for reading. The *writeFileIds* are checked if the specified files are clear for writing. The *exceptFileIds* are checked to see if an exceptional condition has occured (typically, an error). The write and exception checking is most useful on devices, however, the read checking is very useful when communicating with multiple processes through pipes. Select considers data pending in the stdio input buffer for read files as being ready for reading, the files do. not have to be unbuffered. *Timeout* is a floating point timeout value, in seconds. If an empty list is supplied (or the parameter is omitted), then no timeout is set. If the value is zero, then the **select** command functions as a poll of the files, returning immediately even if none are ready. If the *timeout* period expires with none of the files becomming ready, then the command returns an empty list. Otherwise the command returns a list of three elements, each of those elements is a list of the fileIds that are ready in the read, write and exception classes. If none are ready in a class, then that element will be the null list. For example: ``` select {file3 file4 file5} {file6 file7} {} 10.5 could return {file3 file4} {file6} {} or perhaps file3 {} {} ``` - **write\_file *fileName string ?string...?*** This procedure writes the specified strings to the named file. ## TCP/IP SERVER ACCESS Commands are provided to access TCP/IP-based servers, and to create them. It is easy to build servers using Extended Tcl that run under **inetd**, or even servers that run standalone and accept and manage multiple simultaneous connections. The socket file handles maybe be read using the either the **gets** or **read** command and written using either the **puts** or **server\_send** command. The **fstat remotehost** and **fstat localhost** requests are useful both for clients and servers. To obtain the host name of the system the script is running on, use **id host**. If a TclX script is setup to run under **inetd**, it is launched with its stdin, stdout and stderr associated with the client socket. The standard Tcl file ids **stdin**, **stdout** and **stderr** maybe then be used to communicate with the client. - **server\_connect ?*options*? *host service*** Open a TCP/IP connection to a server of *host* on the port specified by *service*. The server is then accessed using the standard Tcl file I/O commands. *Host* may be a host name or an IP address. *Port* may be a port number of a service name. If a destination host name is supplied and more that one address is valid for the host, the host's addresses will be tried in the order returned until one can be connected to, or the list is exhausted. You may also use the **server\_info** command to obtain the list of valid address. The options are:\ - o **-buf** - Specifies that the file is buffered. When writing to the file, the **flush** command must be used to force data in the buffer to be sent to the server. Buffered access will result in significantly better performance when reading data, and will also improve the performance of a series of writes done without intervening reads. The buffering is only used when accessing the file via the **gets**, **read**, and **puts** commands. The **server\_send** command does not use the buffer. - o **-nobuf** - The file is unbuffered. A single file id, open for both reading and writing, is returned. - o **-twoids** - Return a pair of file ids in a list. The first id is open for read access, the second for write access. The **close** command must be called against both file ids when you are done using the socket and they maybe closed independently. This option is primarily intended to implement compatibility procedures for deprecated commands, however it maybe useful for code that needs to independently manage the read and write ends of the socket. - o **-myip** *ipNumber* - Define the IP number for your side of the connection. This is useful for multi-homed hosts (hosts with more than one IP address). Note that only IP addresses corresponding to network interfaces on your machine may be used. If **-myip** is not specified, the operating system will assign the IP number for you. - o **-myport** *portNumber* - Define the port number for your side of the connection. If the port number is already in use, an error will be returned. If the port number is in the privileged range, the Tcl program will have to be running as superuser, or an error will be returned. - **server\_create ?*options*?** Creates a TCP/IP server socket on the local machine. A file handle is returned upon successful creation. When a connection request is made to the server, the file handle becomes read-ready. Connections can be accepted using **server\_accept**. The file handle can be detected as read-ready using **select**, by using **fcntl** to make the handle nonblocking and then calling **server\_accept**, or by using the **Tk fileevent** command. Options are: - o **-myip** *ipNumber* - Define the IP number for your side of the connection. This is useful for multi-homed hosts (hosts with more than one IP address). Note that only IP addresses corresponding to network interfaces on your machine may be used. If **-myip** is not specified, the operating system will assign the IP number for you. - o **-myport** *portNumber* - Define the port number for your side of the connection. If the port number is already in use, an error will be returned. If the port number is in the privileged range, the Tcl program will have to be running as superuser, or an error will be returned. - o **-backlog** *count* - Maximum length the queue of pending connections may grow to. If a connection request arrives with the queue full, the client may receive an error with an indication of *ECONNREFUSED*, or, if the underlying protocol supports retransmission, the request may be ignored so that retries may succeed. Note that on at least some BSD-based systems the backlog is silently limited to 5, regardless of the value specified. The default is 5. - o **-reuseaddr** - Allow reuse of local addresses. - **server\_accept ?*options*? *fileid*** Accept a TCP/IP connection to the server socket associated with *fileid*. Options are **-buf**, **-nobuf** and **-twoids**. See the **server\_connect** command for a description of these options. A file handle (or a pair of file handles when **-twoids**) is return. - **server\_info addresses *host*** **server\_info official\_name *host***\ **server\_info aliases *host***\ Optain information about a TCP/IP server. The argument **host** can be either a host name or an IP address. The following subcommands are recognized: - o **addresses** - Return the list of IP addresses for *host*. - o **official\_name** - Return official name for *host*. - o **aliases** - Return the list of aliases for *host*. (Note that these are IP number aliases, not DNS *CNAME* aliases. See *ifconfig(2)*.) - **server\_send *?options?* *fileid* *string*** Send the specified string to the TCP/IP connection corresponding to *fileid*. The**server\_send** command is provide as an option to **puts** for writing to a socket as it is better at detecting lost connections and other IP-related error conditions. File buffering is ignored for **server\_send**. There is no need to **flush** after a **server\_send**. The results of mixing **server\_send** with **puts** without flushing the **puts** output is indeterminate. Options are: - o **-nonewline** - Don't append a newline character to the end of the message. The default is to append a newline character. - o **-dontroute** - Requests that routing be bypassed and the direct interface used (usually used only by diagnostic or routing programs) - o **-outofband** - Send out-of-band data on the socket. - **server\_cntl *fileid* *attribute* *\[value\]*** Set or get the value of a socket attribute. Attributes are: - o **KEEPALIVE** - Keep connection alive. If SIGPIPE is enabled, then it is sent if connection is broken and data is written to the socket. Note that SIGPIPE is set to be ignored by the Tcl library to support pipes to processes in the **exec** and **open** commands. If SIGPIPE is ignored, an error is returned on the write. Use server\_send to detect dropped connections reliably, Boolean value. If *value* is specifice, the options is set to that value. Otherwise, the value is returned. ## FILE SCANNING COMMANDS These commands provide a facility to scan files, matching lines of the file against regular expressions and executing Tcl code on a match. With this facility you can use Tcl to do the sort of file processing that is traditionally done with *awk*. And since Tcl's approach is more declarative, some of the scripts that can be rather difficult to write in awk are simple to code in Tcl. File scanning in Tcl centers around the concept of a *scan context*. A scan context contains one or more match statements, which associate regular expressions to scan for with Tcl code to be executed when the expressions are matched. - **scancontext ?*option*?** This command manages file scan contexts. A scan context is a collection of regular expressions and commands to execute when that regular expression matches a line of the file. A context may also have a single default match, to be applied against lines that do not match any of the regular expressions. Multiple scan contexts may be defined and they may be reused on multiple files. A scan context is identified by a context handle. The **scancontext** command takes the following forms: - **scancontext create** Create a new scan context. The **scanmatch** command is used to define patterns in the context. A contexthandle is returned, which the Tcl programmer uses to refer to the newly created scan context in calls to the Tcl file scanning commands. - **scancontext delete *contexthandle*** Delete the scan context identified by *contexthandle*, and free all of the match statements and compiled regular expressions associated with the specified context. - **scancontext copyfile *contexthandle* ?*filehandle*?** Set or return the file handle that unmatched lines are copied to. (See **scanfile**). If *filehandle* is omitted, the copy file handle is returned. If no copy file is associated with the context, {} is returned. If a file handle is specified, it becomes the copy file for this context. If *filehandle* is {}, then it removes any copy file specification for the context. - **scanfile ?*-copyfile copyFileId*? *contexthandle* *fileId*** Scan the file specified by *fileId*, starting from the current file position. Check all patterns in the scan context specified by *contexthandle* against it, executing the match commands corresponding to patterns matched. If the optional *-copyfile* argument is specified, the next argument is a file ID to which all lines not matched by any pattern (excluding the default pattern) are to be written. If the copy file is specified with this flag, instead of using the **scancontext copyfile** command, the file is disassociated from the scan context at the end of the scan. - **scanmatch ?-nocase? *contexthandle* ?*regexp*? *commands*** Specify Tcl *commands*, to be evaluated when *regexp* is matched by a **scanfile** command. The match is added to the scan context specified by *contexthandle*. Any number of match statements may be specified for a give context. *Regexp* is a regular expression (see the **regexp** command). If **-nocase** is specified as the first argument, the pattern is matched regardless of alphabetic case. If *regexp* is not specified, then a default match is specified for the scan context. The default match will be executed when a line of the file does not match any of the regular expressions in the current scancontext. The array **matchInfo** is available to the Tcl code that is executed when an expression matches (or defaults). It contans information about the file being scanned and where within it the expression was matched. **matchInfo** is local to the top level of the match command unless declared global at that level by the Tcl **global** command. If it is to be used as a global, it *must* be declared global before **scanfile** is called (since **scanfile** sets the **matchInfo** before the match code is executed, a subsequent **global** will override the local variable). The following array entries are available: - **matchInfo(line)** Contains the text of the line of the file that was matched. - **matchInfo(offset)** The byte offset into the file of the first character of the line that was matched. - **matchInfo(linenum)** The line number of the line that was matched. This is relative to the first line scanned, which is usually, but not necessarily, the first line of the file. The first line is line number one. - **matchInfo(context)** The context handle of the context that this scan is associated with. - **matchInfo(handle)** The file id (handle) of the file currently being scanned. - **matchInfo(copyHandle)** The file id (handle) of the file specified by the **-copyfile** option. The element does not exist if **-copyfile** was not specified. - **matchInfo(submatch0)** Will contain the characters matching the first parenthesized subexpression. The second will be contained in **submatch1**, etc. - **matchInfo(subindex0)** Will contain the a list of the starting and ending indices of the string matching the first parenthesized subexpression. The second will be contained in **subindex1**, etc. All **scanmatch** patterns that match a line will be processed in the order in which their specifications were added to the scan context. The remainder of the **scanmatch** pattern-command pairs may be skipped for a file line if a **continue** is executed by the Tcl code of a preceding, matched pattern. If a **return** is executed in the body of the match command, the **scanfile** command currently in progress returns, with the value passed to **return** as its return value. ## MATH COMMANDS Several extended math commands commands make many additional math functions available in TclX. In addition, a set of procedures provide command access to the math functions supported by the **expr** command. The following procedures provide command interfaces to the expr math functions. They take the same arguments as the **expr** functions and may take expressions as arguments. ``` abs acos asin atan2 atan ceil cos cosh double exp floor fmod hypot int log10 log pow round sin sinh sqrt tan tanh ``` - **max *num1 num2* ?..*numN*?** - **expr max(num1, num2)** Returns the argument that has the highest numeric value. Each argument may be any integer or floating point value. This functionality is also available as a math function **max** in the Tcl **expr** command. - **min *num1 num2* ?..*numN*?** - **expr min(num1, num2)** Returns the argument that has the lowest numeric value. Each argument may be any integer or floating point value. This functionality is also available as a math function **min** in the Tcl **expr** command. - **random *limit* \| seed ?*seedval*?** Generate a pseudorandom integer number greater than or equal to zero and less than *limit*. If **seed** is specified, then the command resets the random number generator to a starting point derived from the **seedval**. This allows one to reproduce pseudorandom number sequences for testing purposes. If *seedval* is omitted, then the seed is set to a value based on current system state and the current time, providing a reasonably interesting and ever-changing seed. ## LIST MANINIPULATION COMMANDS Extended Tcl provides additional list manipulation commands and procedures. - **intersect *lista listb*** Procedure to return the logical intersection of two lists. The returned list will be sorted. - **intersect3 *lista listb*** Procedure to intersects two lists, returning a list containing three lists: The first list returned is everything in *lista* that wasn't in *listb*. The second list contains the intersection of the two lists, and the third list contains all the elements that were in *listb* but weren't in *lista*. The returned lists will be sorted. - **lassign *list var* ?*var*...?** Assign successive elements of a list to specified variables. If there are more variable names than fields, the remaining variables are set to the empty string. If there are more elements than variables, a list of the unassigned elements is returned. For example, ``` lassign {dave 100 200 {Dave Foo}} name uid gid longName ``` Assigns *name* to \`\`dave'', *uid* to \`\`100'', *gid* to \`\`200'', and *longName* to \`\`Dave Foo''. - **lempty *list*** Determine if the specified list is empty. If empty, 1 is returned, otherwise, 0 is returned. This command is an alternative to comparing a list to an empty string. - **lmatch ?*mode*? *list pattern*** Search the elements of *list*, returning a list of all elements matching *pattern*. If none match, an empty list is returned. The *mode* argument indicates how the elements of the list are to be matched against *pattern* and it must have one of the following values: **-exact** The list element must contain exactly the same string as *pattern*. **-glob** *Pattern* is a glob-style pattern which is matched against each list element using the same rules as the **string match** command. **-regexp** *Pattern* is treated as a regular expression and matched against each list element using the same rules as the **regexp** command. If *mode* is omitted then it defaults to **-glob**. - **lrmdups *list*** Procedure to remove duplicate elements from a list. The returned list will be sorted. - **lvarcat** *var string ?string...*? This command treats each *string* argument as a list and concatenates them to the end of the contents of *var*, forming a a single list. The list is stored back into *var* and also returned as the result. if *var* does not exist, it is created. - **lvarpop *var* ?*indexExpr*? ?*string*?** The **lvarpop** command pops (deletes) the element indexed by the expression *indexExpr* from the list contained in the variable *var*. If *index* is omitted, then 0 is assumed. If *string*, is specified, then the deleted element is replaced by *string*. The replaced or deleted element is returned. Thus \`\`lvarpop argv 0'' returns the first element of argv, setting argv to contain the remainder of the string. If the expression *indexExpr* starts with the string **end**, then **end** is replaced with the index of the last element in the list. If the expression starts with **len**, then **len** is replaced with the length of the list. - **lvarpush *var string* ?*indexExpr*?** The **lvarpush** command pushes (inserts) *string* as an element in the list contained in the variable *var*. The element is inserted before position *indexExpr* in the list. If *index* is omitted, then 0 is assumed. If *var* does not exists, it is created. If the expression *indexExpr* starts with the string **end**, then **end** is replaced with the index of the last element in the list. If the expression starts with **len**, then **len** is replaced with the length of the list. Note the a value of **end** means insert the string before the last element. - **union *lista listb*** Procedure to return the logical union of the two specified lists. Any duplicate elements are removed. ## KEYED LISTS Extended Tcl defines a special type of list referred to as *keyed lists*. These lists provided a structured data type built upon standard Tcl lists. This provides a functionality similar to *struct*s in the C programming language. A keyed list is a list in which each element contains a key and value pair. These element pairs are stored as lists themselves, where the key is the first element of the list, and the value is the second. The key-value pairs are refered to as *fields*. This is an example of a keyed list: - {{NAME {Frank Zappa}} {JOB {musician and composer}}} If the variable **person** contained the above list, then **keylget person NAME** would return **{Frank Zappa}**. Executing the command: - **keylset person ID 106** would make **person** contain - {{ID 106} {NAME {Frank Zappa}} {JOB {musician and composer}} Fields may contain subfields; \`.' is the seperator character. Subfields are actually fields where the value is another keyed list. Thus the following list has the top level fields *ID* and *NAME*, and subfields *NAME.FIRST* and *NAME.LAST*: - {ID 106} {NAME {{FIRST Frank} {LAST Zappa}}} There is no limit to the recursive depth of subfields, allowing one to build complex data structures. Keyed lists are constructed and accessed via a number of commands. All keyed list management commands take the name of the variable containing the keyed list as an argument (i.e. passed by reference), rather than passing the list directly. - **keyldel *listvar* *key*** Delete the field specified by *key* from the keyed list in the variable *listvar*. This removes both the key and the value from the keyed list. - **keylget *listvar* ?*key*? ?*retvar* \| {}?** Return the value associated with *key* from the keyed list in the variable *listvar*. If *retvar* is not specified, then the value will be returned as the result of the command. In this case, if *key* is not found in the list, an error will result. If *retvar* is specified and *key* is in the list, then the value is returned in the variable *retvar* and the command returns **1** if the key was present within the list. If *key* isn't in the list, the command will return **0**, and *retvar* will be left unchanged. If **{}** is specified for *retvar*, the value is not returned, allowing the Tcl programmer to determine if a key is present in a keyed list without setting a variable as a side-effect. If *key* is omitted, then a list of all the keys in the keyed list is returned. - **keylkeys *listvar* ?*key*?** Return the a list of the keyes in the keyed list in the variable *listvar*. If *keys* is specified, then it is the name of a key field who's subfield keys are to be retrieve. - **keylset** *listvar* *key* *value* ?*key2* *value2* ...? Set the value associated with *key*, in the keyed list contained in the variable *listvar*, to *value*. If listvar does not exists, it is created. If *key* is not currently in the list, it will be added. If it already exists, *value* replaces the existing value. Multiple keywords and values may be specified, if desired. ## STRING AND CHARACTER MANIPULATION COMMANDS The commands provide additional functionality to classify characters, convert characters between character and numeric values, index into a string, determine the length of a string, extract a range of character from a string, replicate a string a number of times, and transliterate a string (similar to the Unix *tr* program). - **ccollate ?-local? *string1 string2*** This command compares two strings. If returns **-1** if *string1* is less than *string2*, **0** if they are equal amd **1** if *string1* is greater than *string2*. If **-local** is specified, the strings are compared according to the collation environment of the current locale. - **cequal *string1 string2*** This command compares two strings for equality. It returns **1** if *string1* and *string2* are the identical and **0** if they are not. This command is a short-cut for **string compare** and avoids the problems with string expressions being treated unintentionally as numbers. - **cindex *string indexExpr*** Returns the character indexed by the expression *indexExpr* (zero based) from *string*. If the expression *indexExpr* starts with the string **end**, then **end** is replaced with the index of the last character in the string. If the expression starts with **len**, then **len** is replaced with the length of the string. - **clength *string*** Returns the length of *string* in characters. This command is a shortcut for: ``` string length string ``` - **crange *string firstExpr lastExpr*** Returns a range of characters from *string* starting at the character indexed by the expression *firstExpr* (zero-based) until the character indexed by the expression *lastExpr*. If the expression *firstExpr* or **lastExpr** starts with the string **end**, then **end** is replaced with the index of the last character in the string. If the expression starts with **len**, then **len** is replaced with the length of the string. - **csubstr *string firstExpr lengthExpr*** Returns a range of characters from *string* starting at the character indexed by the expression *firstExpr* (zero-based) for *lengthExpr* characters. If the expression *firstExpr* or **lengthExpr** starts with the string **end**, then **end** is replaced with the index of the last character in the string. If the expression starts with **len**, then **len** is replaced with the length of the string. - **ctoken *strvar separators*** Parse a token out of a character string. The string to parse is contained in the variable named *strvar*. The string *separators* contains all of the valid separator characters for tokens in the string. All leading separators are skipped and the first token is returned. The variable *strvar* will be modified to contain the remainder of the string following the token. - **ctype *?-failindex var? class string*** **ctype** determines whether all characters in *string* are of the specified *class*. It returns **1** if they are all of *class*, and **0** if they are not, or if the string is empty. This command also provides another method (besides **format** and **scan**) of converting between an ASCII character and its numeric value. The following **ctype** commands are available: - **ctype *?-failindex var? alnum string*** Tests that all characters are alphabetic or numeric characters as defined by the character set. - **ctype *?-failindex var? alpha string*** Tests that all characters are alphabetic characters as defined by the character set. - **ctype *?-failindex var? ascii string*** Tests that all characters are an ASCII character (a non-negative number less than 0200). - **ctype char *number*** Converts the numeric value, *string*, to an ASCII character. Number must be in the range 0 through 255. - **ctype *?-failindex var? cntrl string*** Tests that all characters are \`\`control characters'' as defined by the character set. - **ctype *?-failindex var? digit string*** Tests that all characters are valid decimal digits, i.e. 0 through 9. - **ctype *?-failindex var? graph string*** Tests that all characters within are any character for which *ctype print* is true, except for space characters. - **ctype *?-failindex var? lower string*** Tests that all characters are lowercase letters as defined by the character set. - **ctype ord *character*** Convert a character into its decimal numeric value. The first character of the string is converted. - **ctype *?-failindex var? space string*** Tests that all characters are either a space, horizontal-tab, carriage return, newline, vertical-tab, or form-feed. - **ctype *?-failindex var? print string*** Tests that all characters are a space or any character for which *ctype* *alnum* or *ctype punct* is true or other \`\`printing character'' as defined by the character set. - **ctype *?-failindex var? punct string*** Tests that all characters are made up of any of the characters other than the ones for which **alnum**, **cntrl**, or **space** is true. - **ctype *?-failindex var? upper string*** Tests that all characters are uppercase letters as defined by the character set. - **ctype *?-failindex var? xdigit string*** Tests that all characters are valid hexadecimal digits, that is *0* through *9*, a through *f* or *A* through *F*. If *-failindex* is specified, then the index into *string* of the first character that did not match the class is returned in *var*. - **replicate *string countExpr*** Returns *string*, replicated the number of times indicated by the expression *countExpr*. - **translit *inrange outrange string*** Translate characters in *string*, changing characters occuring in *inrange* to the corresponding character in *outrange*. *Inrange* and *outrange* may be list of characters or a range in the form \`A-M'. For example: ``` translit a-z A-Z foobar returns "FOOBAR". ``` ## XPG/3 MESSAGE CATALOG COMMANDS These commands provide a Tcl interface to message catalogs that are compliant with the X/Open Portability Guide, Version 3 (XPG/3). Tcl programmers can use message catalogs to create applications that are language-independent. Through the use of message catalogs, prompts, messages, menus and so forth can exist for any number of languages, and they can altered, and new languages added, without affecting any Tcl or C source code, greatly easing the maintenance difficulties incurred by supporting multiple languages. A default text message is passed to the command that fetches entries from message catalogs. This allows the Tcl programmer to create message catalogs containing messages in various languages, but still have a set of default messages available regardless of the presence of any message catalogs, and allow the programs to press on without difficulty when no catalogs are present. Thus, the normal approach to using message catalogs is to ignore errors on **catopen**, in which case **catgets** will return the default message that was specified in the call. The Tcl message catalog commands normally ignore most errors. If it is desirable to detect errors, a special option is provided. This is normally used only during debugging, to insure that message catalogs are being used. If your Unix implementation does not have XPG/3 message catalog support, stubs will be compiled in that will create a version of **catgets** that always returns the default string. This allows for easy porting of software to environments that don't have support for message catalogs. Message catalogs are global to the process, an application with multiple Tcl interpreters within the same process may pass and share message catalog handles. - **catopen ?-fail\|-nofail? *catname*** Open the message catalog *catname*. This may be a relative path name, in which case the **NLSPATH** environment variable is searched to find an absolute path to the message catalog. A handle in the form **msgcat***N* is returned. Normally, errors are ignored, and in the case of a failed call to **catopen**, a handle is returned to an unopened message catalog. (This handle may still be passed to **catgets** and **catclose**, causing **catgets** to simply return the default string, as described above. If the **-fail** option is specified, an error is returned if the open fails. The option **-nofail** specifies the default behavior of not returning an error when **catopen** fails to open a specified message catalog. If the handle from a failed **catopen** is passed to **catgets**, the default string is returned. - **catgets *catHandle setnum msgnum defaultstr*** Retrieve a message form a message catalog. *CatHandle* should be a Tcl message catalog handle that was returned by **catopen**. *Setnum* is the message set number, and *msgnum* is the message number. If the message catalog was not opened, or the message set or message number cannot be found, then the default string, *defaultstr*, is returned. - **catclose ?-fail\|-nofail? *cathandle*** Close the message catalog specified by *cathandle*. Normally, errors are ignored. If **-fail** is specified, any errors closing the message catalog file are returned. The option **-nofail** specifies the default behavior of not returning an error. The use of **-fail** only makes sense if it was also specified in the call to **catopen**. ## EXTENDED TCL SHELL **tcl ?-qn? ?-f? *script*?\|?-c *command*? ?*args*?** **Tcl** starts the interactive Tcl command interpreter. The Tcl shell provides an environment for writing, debugging and executing Tcl scripts. The functionality of the Tcl shell can be easily obtained by any application that includes Tcl. The **tcl** command, issued without any arguments, invokes an interactive Tcl shell, allowing the user to interact directly with Tcl, executing any Tcl commands at will and viewing their results. If *script* is specified, then the script is executed non-interactively with any additional arguments, *args*, being supplied in the global Tcl variable \`**argv**'. If *command* is supplied, then this command (or semicolon-separated series of commands) is executed, with \`**argv**' containing any *args*. The Tcl shell is intended as an environment for Tcl program development and execution. While it is not a full-featured interactive shell, it provides a comfortable environment for the interactive development of Tcl code. Note that the package library code described here overrides the **unknown** command provided as part of the standard Berkeley Tcl library facility, although Tcl source libraries coded to that standard can be loaded and used by Extended Tcl. The following command line flags are recognized by the Tcl shell command line parser: - **-q** Quick initialization flag. The Tcl initiaization file is not evaluated and the **auto\_path** variable is not set. Tcl auto-load libraries will not be available. - **-n** No procedure call stack dump. The procedure call stack will not be displayed when an error occurs, only the error message. Useful in the #! line of already debugged scripts. - **-f** Takes the next argument as a script for Tcl to source, rather than entering interactive mode. The **-f** flag is optional. Normally the first argument that does not start with a \`-' is taken as the script to execute unless the \`-c' option is specified. Any following arguments are passed to the script via **argv**, thus any other Tcl shell command-line flags must precede this option. - **-c** Take the next argument as a Tcl command to execute. It may contain series of commands to execute, separated by \`;'. Any following arguments are passed in **argv**, thus, as with **-f**, any other Tcl shell flags must precede this option. - **--** Mark the end of the arguments to the Tcl shell. All arguments following this are passed in the Tcl variable **argv**. This is useful to pass arguments without attempting to execute a Tcl script. The result string returned by a command executed from the Tcl shell command line is normally echoed back to the user. If an error occurs, then the string result is displayed, along with the error message. The error message will be preceded by the string \`\`Error:''. The **set** command is a special case. If the command is called to set a variable (i.e. with two arguments), then the result will not be echoed. If only one argument, the name of a variable, is supplied to **set**, then the result will be echoed. If an unknown Tcl command is entered from the command line, then the Unix command path, specified in the environment variable **PATH**, will be searched for a command of the same name. If the command is found, it will be executed with any arguments remaining on the Tcl command line being passed as arguments to the command. This feature is provided to enhance the interactive environment for developing Tcl scripts. Automatic execution of programs in this manner is only supported from the command line, not in script files or in procedures, to reduce confusion and mistakes while programming in Tcl. Scripts should use the Tcl **exec** or **system** commands to run Unix commands. The following variables are set and/or used by the Tcl shell. - **argv0** Contains the name of the Tcl program specified on the command line or the name that the Tcl shell was invoked under if no program was specified. **argc** Contains a count of the number of *argv* arguments (0 if none). **argv** A list containing the arguments passed in from the command line, excluding arguments used by the Tcl shell. The first element is the first passed argument, not the program name. - **tcl\_interactive** Set to **1** if Tcl shell is invoked interactively, or **0** if the Tcl shell is directly executing a script. Normally checked by scripts so that they can function as a standalone application if specified on the command line, but merely load in and not execute if loaded during an interactive invocation of Tcl. - **auto\_path** Path to search to locate Tcl scripts. Used by the **auto\_load** command and the TclX unknown command handler. The path is a Tcl list of directory names. - **tclx\_library** Path to the TclX runtime library. If your running the TclX shell or an appilcation based on it (like wishx), this is the same value returned by "info library". - **tcl\_prompt1** Contains code to run to output the prompt used when interactively prompting for commands. - **tcl\_prompt2** Contains code to run to output the prompt used when interactively prompting for continuation of an incomplete command. - **tclx\_errorHandler** If this variable is set to the name of a procedure, that procedure will be call if an uncaught error occurs. The procedure will be passed a single argument of the error message, however to allow future expansion, the procedure should have a final argument of **args**. The procedure is only called in non-interactive shells. If the procedure returns normally, the program will just exit without any error being issued by the shell. Generally the procedure should exit with a non-zero exit code once the error has been processed. It is not possible to continue executing the code in which the error occurred. This is useful for logging **errorInfo** or e-mailing it to the maintainer. - **TCLXENV** Array that contains information used internally by various Tcl procedures that are part of the TclX shell. Don't change this array unless you know what your doing. When Extended Tcl is installed, the standard runtime files are places in the Tcl master directory, which is configured when Tcl is built. This master directory normally contains the Tcl initialization file (TclInit.tcl), the standard Tcl library file (tcl.tlib) and the help files. The Tcl master directory is named after the version of Tcl it is associated with, e.g. **/usr/local/tclX/7.4a**. The path to the Tcl master directory is available from the **info library** command. The location of the Tcl master directory can be overridden with the **TCL\_LIBRARY** environment variable. The first step in initializing the Tcl shell is to locate the Tcl initialization file, normally **TclInit.tcl**. If an environment variable **TCLINIT** exists, it contains the path to the Tcl initialization file. If the **TCLINIT** environment variable is not set, the file **TclInit.tcl** is used from the default Tcl master directory. **Tcl** then evaulates the Tcl initialization file. The **auto\_path** variable is initialized to the Tcl master directory and may be augmented by the intialization file or the application. Other procedures and variables used by the Extended Tcl shell are also defined by this file. If the Tcl is invoked interactively, it will source a file named *.tclrc* in the user's home directory, if it exists. Tcl is viewed primarily as a programming language, not an interactive shell, so the *.tclrc* is intended for use for loading development utilities, not to support applications, which should not have to rely on the user's environment in such a manner. The Extended Tcl Tk shell, **wishx**, has an additional master directory and initialization file. It use the environment variable **TK\_LIBRARY** to override the default location of the Tk master directory. ## HELP FACILITY The help facility allows one to look up help pages which where extracted from the standard Tcl manual pages and Tcl scripts during Tcl installation. Help files are structured as a multilevel tree of subjects and help pages. Help files are found by searching directories named **help** in the directories listed in the **auto\_path** variable. All of the files in the list of help directories form a virtual root of the help tree. This method allows multiple applications to provide help trees without having the files reside in the same directory. The help facility can be accessed in two ways, as interactive commands in the Extended Tcl shell or as an interactive Tk-based program (if you have built Extended Tcl with Tk). To run the Tk-based interactive help program: ``` tclhelp ?addpaths? ``` Where *addpaths* are additional paths to search for help directories. By default, only the *auto\_path* used by **tclhelp** is search. This will result in help on Tcl, Extended Tcl and Tk. The following interactive Tcl commands and options are provided with the help package: - **help** Help, without arguments, lists of all the help subjects and pages under the current help subject. - **help *subject*** Displays all of help pages and lower level subjects (if any exist) under the subject *subject*. - **help *subject/helppage*** Display the specified help page. The help output is passed through a simple pager if output exceeds 23 lines, pausing waiting for a return to be entered. If any other character is entered, the output is terminated. - **helpcd ?*subject*?** Change the current subject, which is much like the Unix current directory. If *subject* is not specified, return to the top-level of the help tree. Help subject path names may also include \`\`..'' elements. - **helppwd** Displays the current help subject. - **help help \| ?** Displays help on the help facility at any directory level. - **apropos *pattern*** This command locates subjects by searching their one-line descriptions for a pattern. Apropos is useful when you can remember part of the name or description of a command, and want to search through the one-line summaries for matching lines. Full regular expressions may be specified (see the **regexp** command). ## TCL LOADABLE LIBRARIES AND PACKAGES Extended Tcl supports standard Tcl **tclIndex** libraries and package libraries. A package library file can contain multiple independent Tcl packages. A package is a named collection of related Tcl procedures and initialization code. The package library file is just a regular Unix text file, editable with your favorite text editor, containing packages of Tcl source code. The package library file name must have the suffix **.tlib**. An index file with the suffix **.tndx**, corresponding to the package library. The **.tndx** will be automatically created by Tcl whenever it is out of date or missing (provided there is write access to the directory. The variable **auto\_path** contains a list of directories that are searched for libraries. The first time an unknown command trap is take, the indexes for the libraries are loaded into memory. If the **auto\_path** variable is changed during execution of a program, it will be re-searched. Only the first package of a given name found during the execution of a program is loaded. This can be overridden with **loadlibindex** command. The start of a package is delimited by: - **#@package: *package\_name proc1* ?*..procN*?** These lines must start in column one. Everything between the **#@package:** keyword and the next **#@package:** keyword or a **#@packend** keyword, or the end of the file, becomes part of the named package. The specified procedures, *proc1..procN*, are the entry points of the package. When a command named in a package specification is executed and detected as an unknown command, all code in the specified package will be sourced. This package should define all of the procedures named on the package line, define any support procedures required by the package and do any package-specific initialization. Packages declarations maybe continued on subsequent lines using standard Tcl backslash line continuations. The **#@packend** keyword is useful to make sure only the minimum required section of code is sourced. Thus for example a large comment block at the beginning of the next file won't be loaded. Care should be taken in defining *package\_name*, as the first package found in the path by with a given name is loaded. This can be useful in developing new version of packages installed on the system. For example, in a package source file, the presence of the following line: - **#@package: directory\_stack pushd popd dirs** says that the text lines following that line in the package file up to the next *package* line or the end of the file is a package named **directory\_stack** and that an attempt to execute either *pushd*, *popd* or *dirs* when the routine is not already defined will cause the **directory\_stack** portion of the package file to be loaded. ## PACKAGE LIBRARY MANAGEMENT COMMANDS Several commands are available for building and managing package libraries. Commands that are extended versions of the standard Tcl library commands are listed here. All of the standard Tcl library management commands and variables are also supported. - **auto\_commands ?-loaders?** Lists the names of all known loadable procedures and commands procedures. If **-loaders** is specified, the command that will be executed to load the command will also be returned. - **buildpackageindex *libfilelist*** Build index files for package libraries. The argument *libfilelist* is a list of package libraries. Each name must end with the suffix **.tlib**. A corresponding **.tndx** file will be built. The user must have write access to the directory containing each library. - **convert\_lib *tclIndex packagelib ?ignore?*** Convert a Ousterhout style *tclIndex* index file and associate source files into a package library **packagelib**. If **packagelib** does not have a **.tlib** extension, one will be added. Any files specified in *tclIndex* that are in the list *ignore* will be skipped. Files listed in *ignore* should just be the base file names, not full paths. - **auto\_load *?command?*** Attempt to load the specified *command* from a loadable library. loading the package containing the procedure. If the package indexes have not been loaded for all package libraries in **auto\_path**, they will be loaded. Out-of-date library indexes will be rebuilt if they are writable. The procedure returns **1** if the command was sucessfully loaded, or **0** if it was not. Duplicated package names are skipped, the first package of a given name found in the path is loaded. If the **auto\_path** has changed since the last load, indexes will be reloaded (duplicate packages will not be redefined). If *command* is not specified, the indexes will be loaded, if they have not alreay been loaded or if the **auto\_path** variable has changed, but no command will be loaded. This command overrides the standard Tcl procedure of the same name. - **loadlibindex *libfile.tlib*** Load the package library index of the library file **libfile** (which must have the suffix *.tlib*). Package library indexes along the **auto\_path** are loaded automatically on the first **demand\_load**; this command is provided to explicitly load libraries that are not in the path. If the index file (with a *.tndx* suffix) does not exists or is out of date, it will be rebuilt if the user has directory permissions to create it. If a package with the same name as a package in *libfile.tlib* has already been loaded, its definition will be overridden by the new package. However, if any procedure has actually been used from the previously defined package, the procedures from *libfile.tlib* will not be loaded. This command will also load an index built by **mkindex.tcl** program supplied with standard Tcl. This file must be named "**tclIndex**". - **auto\_packages ?*-location*?** Returns a list of the names of all defined packages. If *-location* is specified, a list of pairs of package name and the **.tlib** path name, offset and length of the package within the library. - **auto\_load\_file *file*** Source a file, as with the **source** command, except search **auto\_path** for the file. - **searchpath *path file*** Search all directories in the specified path, which is a Tcl list, for the specified file. Returns the full path name of the file, or an empty string if the requested file could not be found.