---
name: "calc"
section: "1"
platform: "linux"
package: "calc"
version: "2.17.0.2-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/calc"
---

# calc(1)

arbitrary precision calculator

## NAME

calc - arbitrary precision calculator

## SYNOPSIS

*calc* \[**-c**\] \[**-C**\] \[**-d**\]\
 \[**-D calc\_debug\[:resource\_debug\[:user\_debug\]\]**\]\
 \[**-e**\] \[**-f filename**\] \[**-h**\] \[**-i**\] \[**-m mode**\] \[**-O**\]\
 \[**-p**\] \[**-q**\] \[**-s**\] \[**-u**\] \[**-v**\] \[**\[--\] calc\_cmd ...**\]

*#!/usr/bin/calc* \[optional\_other\_flags ...\] **-f**

## DESCRIPTION

- **-c**

  Continue reading command lines even after a scan/parse error has caused the abandonment of a line. Note that this option only deals with scanning and parsing of the calc language. It does not deal with execution or run-time errors.

  For example:

  ```
  calc read many_errors.cal
  ```

  will cause **calc** to abort on the first syntax error, whereas:

  ```
  calc -c read many_errors.cal
  ```

  will cause **calc** to try to process each line being read despite the scan/parse errors that it encounters.

  By default, calc startup resource files are silently ignored if not found. This flag will report missing startup resource files unless **-d** is also given.

- **-C**

  Permit the execution of custom builtin functions. Without this flag, calling the custom() builtin function will simply generate an error.

  Use of this flag may cause **calc** to execute functions that are non-standard and that are not portable.  Custom builtin functions are disabled by default for this reason.

- **-d**

  Disable the printing of the opening title.  The printing of resource file debug and informational messages is also disabled as if **config("resource\_debug", 0)** had been executed.

  For example:

  calc "read qtime; qtime(2)"

  will output something like:

  ```
  qtime(utc_hr_offset) defined
  It's nearly ten past six.
  ```

  whereas:

  ```
  calc -d "read qtime; qtime(2)"
  ```

  will just print:

  ```
  It's nearly ten past six.
  ```

  This flag disables the reporting of missing calc startup resource files.

  This flag also disables the printing the leading tilde. For example:

  ```
  calc 2/3
  ```

  will print:

  ```
  ~0.66666666666666666667
  ```

  whereas:

  ```
  calc -d 2/3
  ```

  will just print:

  ```
  0.66666666666666666667
  ```

- **-D** calc\_debug\[:resource\_debug\[:user\_debug\]\]

  Force the initial value of config("calc\_debug"), config("resource\_debug") and config("user\_debug").

  The : separated strings are interpreted as signed 32 bit integers. After an optional leading sign a leading zero indicates octal conversion, and a leading \`\`0x'' or \`\`0X'' hexadecimal conversion.  Otherwise, decimal conversion is assumed.

  By default, *calc\_debug* is 0, *resource\_debug* is 3 and *user\_debug* is 0.

  For more information use the following **calc** command:

  ```
  help config
  ```

- **-e**

  Ignore any environment variables on startup. The getenv() builtin will still return values, however.

- **-f** filename

  This flag is normally only used with calc shell scripts.

  This flag is required when using calc in **shell script mode**. It must be at the end of the initial **#!** line of the script, as in:

  ```
  #!/usr/bin/calc [optional_other_flags ...] -f
  ```

  the rest of the file will be processed in **shell script mode**.

  A common flag to use, prior to the **-f** on the #! line is the **-q** flag. For example:

  ```
  #!/usr/bin/calc -q -f
  ```

  See **SHELL SCRIPT MODE** section of this man page below for details.

  While the actual form of this flag is:

  **-f** filename

  for systems that treat an executable that begins with **#!** as a script, the path of the executable is appended by the kernel as the final argument to the exec() system call. This is why the **-f** flag at the very end of the **#!** line.

  It is possible use **-f** filename on the command line:

  ```
  calc [optional_other_flags ...] -f filename
  ```

  This will cause calc to process lines in **filename** in **shell script mode**.

  **NOTE:** The use of **-f** does **NOT** imply **-q** and thus one would need to use

  ```
  calc [optional_other_flags ...] -q -f filename
  ```

  to disable the use of calc startup files as well.

  The use of **-f** filename implies the **-s** flag.

- **-h**

  Print a help message.  This option implies **-q**. This is equivalent to the **calc** command help help. The help facility is disabled unless the mode is 5 or 7. See **-m**.

- **-i**

  Become interactive if possible. This flag will cause **calc** to drop into interactive mode after the *calc\_cmd* arguments on the command line are evaluated. Without this flag, **calc** will exit after they are evaluated.

  For example:

  ```
  calc 2+5
  ```

  will print the value 7 and exit whereas:

  ```
  calc -i 2+5
  ```

  will print the value 7 and prompt the user for more **calc** commands.

- **-m** mode

  This flag sets the permission mode of **calc**. It controls the ability for **calc** to open files and execute programs. *Mode* may be a number from 0 to 7.

  The mode value is interpreted in a way similar to that of the [**chmod**(1)](/chmod/1.md) octal mode:

  ```
  0  do not open any file, do not execute progs
  1  do not open any file
  2  do not open files for reading, do not execute progs
  3  do not open files for reading
  4  do not open files for writing, do not execute progs
  5  do not open files for writing
  6  do not execute any program
  7  allow everything (default mode)
  ```

  If one wished to run **calc** from a privileged user, one might want to use **-m** 0 in an effort to make **calc** somewhat more secure.

  Mode bits for reading and writing apply only on an open. Files already open are not effected. Thus if one wanted to use the **-m** 0 in an effort to make **calc** somewhat more secure, but still wanted to read and write a specific file, one might want to do in [**sh**(1)](/sh/1.md), [**ksh**(1)](/ksh/1.md), [**bash**(1)](/bash/1.md)-like shells:

  ```
  calc -m 0 3<a.file
  ```

  Files presented to **calc** in this way are opened in an unknown mode. **Calc** will attempt to read or write them if directed.

  If the mode disables opening of files for reading, then the startup resource files are disabled as if **-q** was given. The reading of key bindings is also disabled when the mode disables opening of files for reading.

- **-O**

  Use the old classic defaults instead of the default configuration. This flag as the same effect as executing **config("all", "oldcfg")** at startup time.

  NOTE: Older versions of calc used **-n** to setup a modified form of the default calc configuration. The **-n** flag currently does nothing. Use of the **-n** flag is now deprecated and may be used for something else in the future.

- **-p**

  Pipe processing is enabled by use of **-p**. For example:

  ```
  calc -p "2^21701-1" | fizzbin
  ```

  In pipe mode, **calc** does not prompt, does not print leading tabs and does not print the initial header. The **-p** flag overrides **-i**.

  When running calc as a shell script (see **SHELL SCRIPT MODE** for details), calc will close standard input (stdin) during startup **UNLESS** the **-p** flag is given on the command line. When calc is running in **shell script mode**, shell scripts that call the **prompt**(str) builtin will not work properly (the prompt builtin will always fail) unless the **-p** flag is given on the command line.

- **-q**

  Disable the reading of the startup scripts.

  This allows the script to run independently of startup scripts such those managed by the **$CALCRC** environment variable. For example, this will disable the use of the common calcrc file (usually ~/.calcrc).

- **-s**

  By default, all *calc\_cmd* args are evaluated and executed. This flag will disable their evaluation and instead make them available as strings for the argv() builtin function.

- **-u**

  Disable buffering of stdin and stdout.

- **-v**

  Print the **calc** version number and exit.

- **--**

  The double dash indicates to calc that no more options follow. Thus calc will ignore a later argument on the command line even if it starts with a dash. This is useful when entering negative values on the command line as in:

  ```
  calc -p -- -1 - -7
  ```

## CALC COMMAND LINE

With no *calc\_cmd* arguments, **calc** operates interactively. If one or more arguments are given on the command line and **-s** is NOT given, then **calc** will read and execute them and either attempt to go interactive according as the **-i** flag was present or absent.

If **-s** is given, **calc** will not evaluate any *calc\_cmd* arguments but instead make them available as strings to the argv() builtin function.

Sufficiently simple commands with no characters like parentheses, brackets, semicolons, '\*', which have special interpretations in UNIX shells may be entered, possibly with spaces, until the terminating newline. For example:

```
calc 23 + 47
```

will print 70. However, command lines will have problems:

```
calc 23 * 47

calc -23 + 47
```

The first example above fails because the shell interprets the '\*' as a file glob. The second example fails because '-23' is viewed as a calc option (which it is not) and calc objects to what it thinks of as an unknown option. These cases can usually be made to work as expected by enclosing the command between quotes:

```
calc '23 * 47'

calc "print sqrt(2), exp(1)"
```

or in parentheses and quotes to avoid leading -'s as in:

```
calc '(-23 + 47)'
```

One may also use a double dash to denote that calc options have ended as in:

```
calc -- -23 + 47

calc -q -- -23 + 47
```

If '!' is to be used to indicate the factorial function, for shells like **csh***(1)* for which '!' followed by a non-space character is used for history substitution, it may be necessary to include a space or use a backslash to escape the special meaning of '!'. For example, the command:

```
print 27!^2
```

may have to be replaced by:

```
print 27! ^2    or      print 27\!^2
```

Reading from standard input when calc is part of a pipe works as long as the -p flag is given to calc.  For example, this will print chongo was here:

```
echo chongo was here | calc -p 'print fgetline(files(0));'

```

while this does not:

```
echo chongo was here | calc 'print fgetline(files(0));'

```

nor will this print chongo was here:

```
echo chongo was here | calc -i 'print fgetline(files(0));'

```

This is because without **-p**, the interactive parser, in an effort to parse interactive commands, flushes data on standard input.

## CALC STARTUP FILES

Normally on startup, if the environment variable **$CALCRC** is undefined and **calc** is invoked without the **-q** flag, or if **$CALCRC** is defined and calc is invoked with **-e**, **calc** looks for a file "startup" in the calc resource directory **.calcrc** in the user's home directory, and **.calcinit in the current directory.** If one or more of these are found, they are read in succession as **calc** scripts and their commands executed. When defined, **$CALCRC** is to contain a ':' separated list of names of files, and if calc is then invoked without either the **-q** or **-e** flags, these files are read in succession and their commands executed. No error condition is produced if a listed file is not found.

If the mode specified by **-m** disables opening of files for reading, then the reading of startup files is also disabled as if **-q** was given.

## CALC FILE SEARCH PATH

If the environment variable **$CALCPATH** is undefined, or if it is defined and **calc** is invoked with the **-e** flag, when a file name not beginning with **/**, **~** or **./**, is specified as in:

```
calc read myfile
```

**calc** searches in succession:

```
 ./myfile
 ./myfile.cal
/usr/lib/myfile
/usr/lib/myfile.cal
/usr/share/calc/custom/myfile
/usr/share/calc/custom/myfile.cal
```

If the file is found, the search stops and the commands in the file are executed. It is an error if no readable file with the specified name is found. An alternative search path can be specified by defining **$CALCPATH** in the same way as PATH is defined, as a ':' separated list of directories, and then invoking **calc** without the **-e** flag.

**Calc** treats all open files, other than stdin, stdout and stderr as files available for reading and writing. One may present **calc** with an already open file using [**sh**(1)](/sh/1.md), [**ksh**(1)](/ksh/1.md), [**bash**(1)](/bash/1.md)-like shells is to:

calc 3\<open\_file 4\<open\_file2

For more information use the following **calc** commands:

```
help help
help overview
help usage
help environment
help config
```

## SHELL SCRIPT MODE

If the first line of an executable file begins **#!** followed by the absolute pathname of the **calc** program and the first line ends with the flag **-f** as in:

```
#!/usr/bin/calc [optional_other_flags ...] -f
```

the rest of the file will be processed in **shell script mode**. Note that **-s** **-f** must be at the end of the initial \`\`#!'' line. Any other optional **optional\_other\_flags** must come before the **-f** flag.

In **shell script mode** the contents of the file are read and executed as if they were in a file being processed by a read command, except that a "command" beginning with '#' followed by whitespace and ending at the next newline is treated as a comment. Any optional **optional\_other\_flags** will be parsed first followed by the later lines within the script itself.

In **shell script mode**, **-s** is always assumed. In addition, **-d** and **-p** are automatically set if **-i** is not given.

**NOTE:** The use of **-f** does **NOT** imply **-q** and thus one would need to use

```
calc [optional_other_flags ...] -q -f filename
```

to disable the use of calc startup files as well.

For example, if the file **/tmp/mersenne**:

```
#!/usr/bin/calc -q -f
/* setup */
argc = argv();
program = argv(0);
stderr = files(2);
/* parse args */
if (argc != 2) {
    fprintf(stderr, "usage: %s exp0, program);
    abort "must give one exponent arg";
}
exp = eval(argv(1));
if (!isint(exp) || exp < 0) {
    fprintf(stderr, "%s: exp must be non-negative integer0, program);
    abort "must give one exponent arg";
}
/* print the mersenne number */
print "2^": exp : "-1 =", 2^exp-1;
```

is made an executable file by:

```
chmod +x /tmp/mersenne
```

then the command line:

```
/tmp/mersenne 127
```

will print:

```
2^127-1 = 170141183460469231731687303715884105727
```

Note that because **-s** is required in **shell script mode** non-dashed args are made available as strings via the **argv**() builtin function. Therefore:

```
2^eval(argv(1))-1
```

will print the decimal value of 2^n-1 whereas

```
2^argv(1)-1
```

will not.

By default, using calc startup in **shell script mode**, calc will close standard input (stdin). Thus builtin functions such as **prompt**(str) will fail (return a null value). Calc shell scripts that call the **prompt**(str) builtin will not work properly (the prompt builtin will always fail and return a null value) unless the **-p** flag is given on the command line.

The following shell script will always print "got null" because stdin will be closed by calc during startup:

```
#!/usr/bin/calc -q -f
# The prompt will ALWAYS FAIL and return a null value
n = prompt("Test> ");
if (isnull(n)) {
  print("got null");
} else {
  print("got " + n);
}
```

However the following shell script (note the **-p** before the **-f** in the 1st line) will be interactive, prompt with "Test\> " and print the "got" result as expected:

```
#!/usr/bin/calc -q -p -f
n = prompt("Test> ");
if (isnull(n)) {
  print("got null");
} else {
  print("got " + n);
}
```

Note in the example above, the **-p** flag must be given before the final **-f** command line flag.

## DATA TYPES

Fundamental builtin data types include integers, real numbers, rational numbers, complex numbers and strings.

By use of an object, one may define an arbitrarily complex data types. One may define how such objects behave a wide range of operations such as addition, subtraction, multiplication, division, negation, squaring, modulus, rounding, exponentiation, equality, comparison, printing and so on.

For more information use the following **calc** commands:

help types\
 help obj\
 show objfuncs

## VARIABLES

Variables in *calc* are typeless. In other words, the fundamental type of a variable is determined by its content. Before a variable is assigned a value it has the value of zero.

The scope of a variable may be global, local to a file, or local to a procedure. Values may be grouped together in a matrix, or into a list that permits stack and queue style operations.

For more information use the following **calc** commands:

help variable\
 help mat\
 help list\
 show globals

## INPUT/OUTPUT

A leading \`\`0x'' implies a hexadecimal value, a leading \`\`0b'' implies a binary value, and a \`\`0'' followed by a digit implies an octal value. Complex numbers are indicated by a trailing \`\`i'' such as in \`\`3+4i''. Strings may be delimited by either a pair of single or double quotes. By default, *calc* prints values as if they were floating point numbers. One may change the default to print values in a number of modes including fractions, integers and exponentials.

A number of stdio-like file I/O operations are provided. One may open, read, write, seek and close files. Filenames are subject to \`\` '' expansion to home directories in a way similar to that of the Korn or C-Shell.

For example:

\~/.calcrc\
 \~chongo/lib/fft\_multiply.cal

For more information use the following **calc** command:

help file

## CALC LANGUAGE

The *calc* language is a C-like language. The language includes commands such as variable declarations, expressions, tests, labels, loops, file operations, function calls. These commands are very similar to their counterparts in C.

The language also include a number of commands particular to *calc* itself. These include commands such as function definition, help, reading in resource files, dump files to a file, error notification, configuration control and status.

For more information use the following **calc** command:

help command\
 help statement\
 help expression\
 help operator\
 help config

## FILES

- /usr/bin/calc

  calc binary

- /usr/bin/cscript/\*

  calc shell scripts

- /usr/lib/\*.cal

  calc standard resource files

- /usr/lib/help/\*

  help files

- /usr/lib/bindings

  non-GNU-readline command line editor bindings

- /usr/include/calc/\*.h

  include files for C interface use

- /usr/lib/libcalc.a

  calc binary link library

- /usr/lib/libcustcalc.a

  custom binary link library

- /usr/share/calc/custom/\*.cal

  custom resource files

- /usr/share/calc/custhelp/\*

  custom help files

## ENVIRONMENT

- CALCPATH

  A :-separated list of directories used to search for calc resource filenames that do not begin with /, ./ or ~.\

  If this variable is unset or empty, **calc** first checks $XDG\_DATA\_HOME and $XDG\_CONFIG\_HOME. When both name usable absolute directories, **calc** searches in succession:

  ```
  ${XDG_DATA_HOME}/calc
  ${XDG_CONFIG_HOME}/calc
  ${CALC_SHAREDIR}
  /usr/share/calc/custom
  ```

  If neither XDG directory is usable, the compiled fallback is usually:

  ```
  ~/.cal
  ${CALC_SHAREDIR}
  /usr/share/calc/custom
  ```

- CALCRC

  On startup (unless -h or -q was given on the command line), **calc** searches for files along this :-separated environment variable.\

  If this variable is unset or empty, **calc** first checks $XDG\_CONFIG\_HOME. When it names a usable absolute directory, **calc** searches in succession:

  ```
  ${XDG_CONFIG_HOME}/calc/calcrc
  ${CALC_SHAREDIR}/startup
  ```

  If $XDG\_CONFIG\_HOME is not usable, the compiled fallback is usually:

  ```
  ~/.calcrc
  ${CALC_SHAREDIR}/startup
  ```

- CALCBINDINGS

  On startup (unless *-h* or *-q* was given on the command line, or *-m* disallows opening files for reading), **calc** reads key bindings from the filename specified by this environment variable. The key binding file is searched for along the $CALCPATH list of directories.

  Default value: binding

  This variable is not used if calc was compiled with GNU-readline support. In that case, the standard readline mechanisms (see [readline(3)](/readline/3.md)) are used.

- CALCHISTFILE

  Location of the calc history file.

  If this variable is unset or empty, **calc** first uses an existing **~/.calc\_history** file. Otherwise, **calc** checks $XDG\_STATE\_HOME. When it names a usable absolute writable directory, the effective value is:

  ```
  ${XDG_STATE_HOME}/calc/history
  ```

  If neither applies, the fallback value is:

  ```
  ~/.calc_history
  ```

  This variable is not used if calc was compiled with GNU-readline support.

- CALCHELP

  Location of the calc help directory.

  Default value: /usr/share/calc/help

- CALCCUSTOMHELP

  Location of the calc custom help directory.

  Default value: /usr/share/calc/custhelp

When CALCPATH, CALCRC and CALCHISTFILE are unset or empty, **calc** follows the XDG Base Directory Specification as described above.

You may override those locations by setting the calc environment variables explicitly.  For example, to restore the usual legacy defaults on a typical Unix install:

```
export CALCRC="./.calcinit:$HOME/.calcrc:/usr/share/calc/startup"
export CALCPATH=".:./cal:$HOME/.cal:/usr/share/calc:/usr/share/calc/custom"
export CALCHISTFILE="$HOME/.calc_history"
```

For more information on the XDG Base Directory specification see:

```
https://specifications.freedesktop.org/basedir/latest/
```

Note that **calc** will attempt to create the parent directory of $CALCHISTFILE. If that is not sufficient, you may need to run:

```
mkdir -p $(dirname $CALCHISTFILE)
```

for the history mechanism if you choose a path to a file that does not yet exist.

## CREDIT

The main chunk of **calc** was written by David I. Bell.

The **calc** primary mirror, and calc bug report processing is performed by Landon Curt Noll.

Landon Curt Noll maintains the master reference source, performs release control functions as well as other calc maintenance functions.

Thanks for suggestions and encouragement from Peter Miller, Neil Justusson, and Landon Noll.

Thanks to Stephen Rothwell for writing the original version of hist.c which is used to do the command line editing.

Thanks to Ernest W. Bowen for supplying many improvements in accuracy and generality for some numeric functions.  Much of this was in terms of actual code which I gratefully accepted. Ernest also supplied the original text for many of the help files.

Portions of this program are derived from an earlier set of public domain arbitrarily precision routines which was posted to the net around 1984. By now, there is almost no recognizable code left from that original source.

## COPYING / CALC GNU LESSER GENERAL PUBLIC LICENSE

Calc is open software, and is covered under version 2.1 of the GNU Lesser General Public License. You are welcome to change it and/or distribute copies of it under certain conditions. The calc commands:

```
help copyright
help copying
help copying-lgpl
help credit
```

should display the contents of the COPYING and COPYING-LGPL files. Those files contain information about the calc's GNU Lesser General Public License, and in particular the conditions under which you are allowed to change it and/or distribute copies of it.

You should have received a copy of the version 2.1 of the GNU Lesser General Public License. If you do not have these files, write to:

```
Free Software Foundation, Inc.
51 Franklin Street
Fifth Floor
Boston, MA  02110-1301
USA
```

Calc is copyrighted in several different ways. These ways include:

```
Copyright (C) year  David I. Bell
Copyright (C) year  David I. Bell and Landon Curt Noll
Copyright (C) year  David I. Bell and Ernest Bowen
Copyright (C) year  David I. Bell, Landon Curt Noll and Ernest Bowen
Copyright (C) year  Landon Curt Noll
Copyright (C) year  Ernest Bowen and Landon Curt Noll
Copyright (C) year  Ernest Bowen
Copyright (C) year  Petteri Kettunen and Landon Curt Noll
Copyright (C) year  Christoph Zurnieden
Copyright (C) year  Landon Curt Noll and Thomas Jones-Low
Copyright (C) year  Klaus Alexander Seistrup and Landon Curt Noll
```

A few files in calc are covered under "The Unlicense". For more information on this license, see:

```
https://unlicense.org
```

## CALC QUESTIONS

To ask the calc maintainers a general question about calc, see the output of the following calc command:

```
; help question
```

or read the source file:

```
QUESTIONS
```

or visit the following URL:

```
https://github.com/lcn2/calc/blob/master/QUESTIONS
```

## BUG REPORTS / BUG FIXES

To inform the calc maintainers about a bug, or to submit a bug fix, see the output of the following calc command:

```
; help bugs
```

or read the source file:

```
BUGS
```

or visit the following URL:

```
https://github.com/lcn2/calc/blob/master/BUGS
```

## CONTRIBUTING CODE TO CALC

*Calc* is open source. You are welcome to contribute code to calc, or submit bug fixes to to calc.

To contribute code to calc, please see see the output of the following calc command:

```
; help contrib
```

or read the source file:

```
CONTRIB-CODE
```

or visit the following URL:

```
https://github.com/lcn2/calc/blob/master/CONTRIB-CODE
```

## CALC WEB SITE

Landon Noll maintains the **calc** web site is located at:

www.isthe.com/chongo/tech/comp/calc/

## CALC SOURCE CODE

The latest version of calc source code may be obtained at the following GitHub repo:

https://github.com/lcn2/calc

The very latest calc source is found at the top master branch.

You may download the calc releases from:

https://github.com/lcn2/calc/releases

The releases marked **((Pre-release))** are beta releases.

The most recent release that is NOT  marked **((Pre-release))** is the recommended stable release.