C process control: Difference between revisions

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{{Short description|Functions of the C standard software library}}

{{Use dmy dates|date=January 2022}}

{{C Standard Library}}

{{move to|C process control functions}}

'''C programprocess control operations''' arerefers to a group of functions in the [[C standard library|standard library]] of the [[C programming language]] implementing basic programprocess control operations.<ref>{{cite book|last=Crawford|first=Tony|coauthorsauthor2=Peter Prinz|title=C in a Nutshell|publisher=O'Reilly|___location=§16.11 -– ''Process Control''|date=December 2005|pages=618|isbn=0-596-00697-7}}</ref><ref>{{cite book | url=http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf | title=ISO/IEC 9899:1999 specification | at=p. 315, § 7.20.4 "Communication with the environment" | accessdate=25 November 2011}}</ref> The process control operations include actions such as termination of the program with various levels of cleanup, running an external command interpreter or accessing the list of the environment operations.

| url=http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf

| title=ISO/IEC 9899:1999 specification

| at=p. 315, § 7.20.4 "Communication with the environment"

}}</ref>

==Overview of functions==

The programprocess control functions are defined in the <ttcode>stdlib.h</ttcode> header (<ttcode>cstdlib</ttcode> header in C++).

{| class="wikitable" style="font-size:0.85em"

; Terminating a program

!

*<tt>{{man|sh|abort|SUS||inline}}</tt> - causes abnormal program termination (without cleaning up)

! Function

*<tt>{{man|sh|exit|SUS||inline}}</tt> - causes normal program termination with cleaning up

! Description

*<tt>{{man|sh|_Exit|SUS||inline}}</tt> - causes normal program termination without cleaning up

|-

*<tt>{{man|sh|atexit|SUS||inline}}</tt> - registers a function to be called on exit() invocation

;! rowspan=6 | Terminating <br>a program

| {{anchor|abort}}<code>[http://en.cppreference.com/w/c/program/abort abort]</code>

; Communicating with the environment

*<tt>{{man|sh|abort|SUS||inline}}</tt> - causes abnormal program termination (without cleaning up)

*<tt>{{man|sh|getenv|SUS||inline}}</tt> - accesses the list of the environment variables

|-

*<tt>{{man|sh|system|SUS||inline}}</tt> - calls the host environment's command processor

| {{anchor|exit}}<code>[http://en.cppreference.com/w/c/program/exit exit]</code>

*<tt>{{man|sh|exit|SUS||inline}}</tt> - causes normal program termination with cleaning up

|-

| {{anchor|_Exit}}<code>[http://en.cppreference.com/w/c/program/_Exit _Exit]</code>

*<tt>{{man|sh|_Exit|SUS||inline}}</tt> - causes normal program termination without cleaning up ([[C99]])

|-

| {{anchor|atexit}}<code>[http://en.cppreference.com/w/c/program/atexit atexit]</code>

*<tt>{{man|sh|atexit|SUS||inline}}</tt> - registers a function to be called on exit() invocation

|-

| {{anchor|quick_exit}}<code>[http://en.cppreference.com/w/c/program/quick_exit quick_exit]</code>

| causes normal program termination without cleaning up, but with IO buffers flushed ([[C11 (C standard revision)|C11]])

|-

| {{anchor|quick_exit}}<code>[http://en.cppreference.com/w/c/program/at_quick_exit at_quick_exit]</code>

| registers a function to be called on quick_exit() invocation

|-

;! rowspan=2 | Communicating with <br>the environment

| {{anchor|getenv}}<code>[http://en.cppreference.com/w/c/program/getenv getenv]</code>

*<tt>{{man|sh|getenv|SUS||inline}}</tt> - accesses the list of the environment variables

|-

| {{anchor|system}}<code>[http://en.cppreference.com/w/c/program/system system]</code>

*<tt>{{man|sh|system|SUS||inline}}</tt> - calls the host environment's command processor

|}

==References==

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==External links==

{{wikibooks|C Programming|C program control operations|C Programming/C Reference}}

{{clear}}

[[Category:C Standardstandard Librarylibrary]]