--- name: "cininserter" section: "3bobcat" platform: "linux" package: "libbobcat-dev" version: "6.07.01-2" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/cininserter" --- # cininserter(3bobcat) Runs external programs reading standard input ## NAME FBB::CinInserter - Runs external programs reading standard input ## SYNOPSIS **#include \**\ Linking option: *-lbobcat* ## DESCRIPTION The **FBB::CinInserter** class offers a basic interface for calling external programs (so-called child processes) reading their standard input streams. The standard output and standard error streams of the child processes by default are not handled by *CinInserter* objects. The child’s standard input is provided through the *CinInserter* object: information inserted into an *CinInserter* object is forwarded to the child process’s standard input stream. The *PATH* environment variable is not used when calling child processes: child process programs must be specified using paths. *CinInserter* objects may repeatedly be used to execute the same or different child processes. Before starting the next child process, the current child process must have finished. Arguments passed to child processes may be surrounded by double or single quotes. Arguments surrounded by double quotes have their double quotes removed, while interpreting any escape-sequences that may have been used within. Arguments surrounded by single quotes have their single quotes removed, while accepting their content as-is. In addition unquoted escape-sequences may be specified: those escape sequences are evaluated and replaced by their intended characters (e.g., *\\100* is converted to *@*). When information of undetermined size or structure must be inserted into a child process then the child process cannot determine when to stop. This creates an interesting problem: the child process starts, and the parent process must wait until its child process has finished processing its input. But input can only be forwarded to the child’s input stream after the child process has started. To solve this problem *InterterFork* offers an overloaded *execute* member, passing information to the child process via a separate thread. ## NAMESPACE **FBB**\ All constructors, members, operators and manipulators, mentioned in this man-page, are defined in the namespace **FBB**. ## INHERITS FROM **FBB::Exec** (private), **FBB::OFdBuf** (private), **std::ostream**. ## CONSTRUCTOR - o **CinInserter(size\_t bufSize = 100)**:\ A *bufSize* argument may be specified: it defines the internal buffer size used by the *CinInserter’s* streambuf. By default the stdandard output and standard error streams are not handled. - o **CinInserter(Mode mode, size\_t bufSize = 100)**:\ The *mode* argument must be *CinInserter::CLOSE\_STD*. It indicates that the standard output and standard error streams are redirected to */dev/null*: any standard output generated by child processes is ignored. A *bufSize* argument may be specified: it defines the internal buffer size used by the *CinInserter’s* streambuf. Copy and move constructors (and assignment operators) are not available. ## DESTRUCTOR The destructor ends the *CinInserter’s* child process, if it is still active. ## MEMBERS - o **void execute(std::string const &cmd)**:\ The argument specifies the command to execute: the command itself must be specified as a path (the *PATH* environment variable isn’t used). This member immediately returns, after which information can be inserted into the *CinInserter* object which is then forwarded to the childprocess’s standard input stream. See also the description of the next (overloaded *execute*) member function. - Once all information has been inserted, the child process’s standard input stream must be closed. This is realized by either calling *stop*; by calling *execute* once again; or by ending the *CinInserter* object’s lifetime. - Arguments specified in the *cmd* string are passed to the child process, and may optionally be specified using single or double quotes, as described in this man-page’s DESCRIPTION section. - - o **bool execute(std::string const &cmd, std::string const &text)**:\ This member is used to forward a limited amount of information (contained in the *text* parameter) to the child process specified at *cmd* (defined identically as the *cmd* parameter of the previous *execute* member). - This member returns *true* if the child process’s exit value equals 0. - - o **int stop()**:\ This function can be called after all information has been inserted into the *CinInserter* object to close the child process’s standard input stream. It is not required after calling *execute(cmd, text)*, or when calling *execute* again, or when the *CinInseror* object’s lifetime ends. - This member returns the exit code of the last executed child process, which may also be obtained from the next member: - - o **int ret() const**:\ Once a child process has finished this member provides the actual exit code of the child process. Its value equals -1 before the first *exectue* call. ## PROTECTED MEMBER - o **Pipe &childInPipe()**:\ If derived classes need to override the redirections-members then they probabaly need access to the pipe read by the child process. This member provides a reference to that pipe. By default the parent process inserts information into the pipe, while the child process reads the inserted information from the pipe. ## EXAMPLE ``` #include #include #include using namespace std; using namespace FBB; int main() { CinInserter inserter; inserter.execute("/bin/cat"); ifstream in("build"); inserter << in.rdbuf(); cout << "child returns: " << inserter.stop() << ’\n’; inserter.execute("/bin/cat"); in.seekg(0); // reset to the beginning inserter << in.rdbuf(); // when immediately followed by another execute, ’stop’ is optional inserter.execute("/bin/cat", "a simple text\n"); inserter.execute("/bin/cat", "a simple text\n"); bool bret = inserter.execute("/bin/cat", "a simple text\n"); cout << "direct string insertion: " << bret << ’\n’; } ``` ## FILES *bobcat/cininserter* - provides the class interface ## SEE ALSO [**bobcat**(7)](/bobcat/7.md), [**cerrextractor**(3bobcat)](/cerrextractor/3bobcat.md), [**coutextractor**(3bobcat)](/coutextractor/3bobcat.md), [**execl**(3)](/execl/3.md), [**exec**(3bobcat)](/exec/3bobcat.md), [**fork**(3bobcat)](/fork/3bobcat.md), [**pipe**(3bobcat)](/pipe/3bobcat.md), [**process**(3bobcat)](/process/3bobcat.md), [**stdextractor**(3bobcat)](/stdextractor/3bobcat.md). ## BUGS None reported. ## BOBCAT PROJECT FILES - o *https://fbb-git.gitlab.io/bobcat/*: gitlab project page; Debian Bobcat project files: - o *libbobcat6*: debian package containing the shared library, changelog and copyright note; - o *libbobcat-dev*: debian package containing the static library, headers, manual pages, and developer info; ## BOBCAT Bobcat is an acronym of \`Brokken’s Own Base Classes And Templates’. ## COPYRIGHT This is free software, distributed under the terms of the GNU General Public License (GPL). ## AUTHOR Frank B. Brokken (**f.b.brokken@rug.nl**).