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NAME |LIBRARY |SYNOPSIS |DESCRIPTION |RETURN VALUE |ATTRIBUTES |STANDARDS |HISTORY |NOTES |SEE ALSO |COLOPHON | |
exit(3) Library Functions Manualexit(3)exit - cause normal process termination
Standard C library (libc,-lc)
#include <stdlib.h>[[noreturn]] void exit(intstatus);
Theexit() function causes normal process termination and the least significant byte ofstatus (i.e.,status & 0xFF) is returned to the parent (seewait(2)). All functions registered withatexit(3) andon_exit(3) are called, in the reverse order of their registration. (It is possible for one of these functions to useatexit(3) oron_exit(3) to register an additional function to be executed during exit processing; the new registration is added to the front of the list of functions that remain to be called.) If one of these functions does not return (e.g., it calls_exit(2), or kills itself with a signal), then none of the remaining functions is called, and further exit processing (in particular, flushing ofstdio(3) streams) is abandoned. If a function has been registered multiple times usingatexit(3) oron_exit(3), then it is called as many times as it was registered. All openstdio(3) streams are flushed and closed. Files created bytmpfile(3) are removed. The C standard specifies two constants,EXIT_SUCCESSandEXIT_FAILURE, that may be passed toexit() to indicate successful or unsuccessful termination, respectively.
Theexit() function does not return.
For an explanation of the terms used in this section, seeattributes(7). ┌──────────────────────────┬───────────────┬─────────────────────┐ │Interface│Attribute│Value│ ├──────────────────────────┼───────────────┼─────────────────────┤ │exit() │ Thread safety │ MT-Unsafe race:exit │ └──────────────────────────┴───────────────┴─────────────────────┘ Theexit() function uses a global variable that is not protected, so it is not thread-safe.
C11, POSIX.1-2008.
C89, POSIX.1-2001, SVr4, 4.3BSD.
The behavior is undefined if one of the functions registered usingatexit(3) andon_exit(3) calls eitherexit() orlongjmp(3). Note that a call toexecve(2) removes registrations created usingatexit(3) andon_exit(3). The use ofEXIT_SUCCESSandEXIT_FAILUREis slightly more portable (to non-UNIX environments) than the use of 0 and some nonzero value like 1 or -1. In particular, VMS uses a different convention. BSD has attempted to standardize exit codes (which some C libraries such as the GNU C library have also adopted); see the file<sysexits.h>. Afterexit(), the exit status must be transmitted to the parent process. There are three cases: • If the parent has setSA_NOCLDWAIT, or has set theSIGCHLD handler toSIG_IGN, the status is discarded and the child dies immediately. • If the parent was waiting on the child, it is notified of the exit status and the child dies immediately. • Otherwise, the child becomes a "zombie" process: most of the process resources are recycled, but a slot containing minimal information about the child process (termination status, resource usage statistics) is retained in process table. This allows the parent to subsequently usewaitpid(2) (or similar) to learn the termination status of the child; at that point the zombie process slot is released. If the implementation supports theSIGCHLDsignal, this signal is sent to the parent. If the parent has setSA_NOCLDWAIT, it is undefined whether aSIGCHLDsignal is sent.Signals sent to other processes If the exiting process is a session leader and its controlling terminal is the controlling terminal of the session, then each process in the foreground process group of this controlling terminal is sent aSIGHUPsignal, and the terminal is disassociated from this session, allowing it to be acquired by a new controlling process. If the exit of the process causes a process group to become orphaned, and if any member of the newly orphaned process group is stopped, then aSIGHUPsignal followed by aSIGCONTsignal will be sent to each process in this process group. Seesetpgid(2) for an explanation of orphaned process groups. Except in the above cases, where the signalled processes may be children of the terminating process, termination of a process doesnot in general cause a signal to be sent to children of that process. However, a process can use theprctl(2)PR_SET_PDEATHSIG operation to arrange that it receives a signal if its parent terminates.
_exit(2),get_robust_list(2),setpgid(2),wait(2),atexit(3),on_exit(3),tmpfile(3)
This page is part of theman-pages (Linux kernel and C library user-space interface documentation) project. Information about the project can be found at ⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report for this manual page, see ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩. This page was obtained from the tarball man-pages-6.15.tar.gz fetched from ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on 2025-08-11. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up- to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which isnot part of the original manual page), send a mail to man-pages@man7.orgLinux man-pages 6.15 2025-05-17exit(3)Pages that refer to this page:man(1), _exit(2), kill(2), vfork(2), wait(2), abort(3), assert(3), assert_perror(3), atexit(3), err(3), error(3), EXIT_SUCCESS(3const), on_exit(3), pthread_create(3), pthread_detach(3), pthread_exit(3), sd_bus_set_exit_on_disconnect(3), setjmp(3), stdin(3), stdio(3), sysexits.h(3head), tmpfile(3)
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