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}}

'''C process control''' refers to a group of functions in the [[C standard library|standard library]] of the [[C programming language]] implementing basic process 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.

==Overview of functions==

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

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

; Terminating a program

!

*{{anchor|abort}}<code>[http://en.cppreference.com/w/cpp/utility/program/abort abort]</code> - causes abnormal program termination (without cleaning up)

! Function

*{{anchor|exit}}<code>[http://en.cppreference.com/w/cpp/utility/program/exit exit]</code> - causes normal program termination with cleaning up

! Description

*{{anchor|_Exit}}<code>[http://en.cppreference.com/w/cpp/utility/program/_Exit _Exit]</code> - causes normal program termination without cleaning up

|-

*{{anchor|atexit}}<code>[http://en.cppreference.com/w/cpp/utility/program/atexit atexit]</code> - registers a function to be called on exit() invocation

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

*| {{anchor|abort}}<code>[http://en.cppreference.com/w/cpp/utilityc/program/abort abort]</code> - causes abnormal program termination (without cleaning up)

; Communicating with the environment

| causes abnormal program termination (without cleaning up)

*{{anchor|getenv}}<code>[http://en.cppreference.com/w/cpp/utility/program/getenv getenv]</code> - accesses the list of the environment variables

|-

*{{anchor|system}}<code>[http://en.cppreference.com/w/cpp/utility/program/system system]</code> - calls the host environment's command processor

*| {{anchor|exit}}<code>[http://en.cppreference.com/w/cpp/utilityc/program/exit exit]</code> - causes normal program termination with cleaning up

| causes normal program termination with cleaning up

|-

*| {{anchor|_Exit}}<code>[http://en.cppreference.com/w/cpp/utilityc/program/_Exit _Exit]</code> - causes normal program termination without cleaning up

| causes normal program termination without cleaning up ([[C99]])

|-

*| {{anchor|atexit}}<code>[http://en.cppreference.com/w/cpp/utilityc/program/atexit atexit]</code> - registers a function to be called on exit() invocation

| 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/cpp/utilityc/program/getenv getenv]</code> - accesses the list of the environment variables

| accesses the list of the environment variables

|-

*| {{anchor|system}}<code>[http://en.cppreference.com/w/cpp/utilityc/program/system system]</code> - calls the host environment's command processor

| 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}}

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[[Category:C Standard Library]]

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[[Category:C Standardstandard Librarylibrary]]

[[es:Stdlib.h]]

[[fa:Stdlib.h]]

[[ko:Stdlib.h]]

[[it:Stdlib.h]]

[[pt:Stdlib.h]]

[[ru:Stdlib.h]]