1.\" Copyright (c) 1990, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" the American National Standards Committee X3, on Information 6.\" Processing Systems. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.Dd July 24, 2024 33.Dt EXIT 3 34.Os 35.Sh NAME 36.Nm exit , _Exit 37.Nd perform normal program termination 38.Sh LIBRARY 39.Lb libc 40.Sh SYNOPSIS 41.In stdlib.h 42.Ft void 43.Fn exit "int status" 44.Ft void 45.Fn _Exit "int status" 46.Sh DESCRIPTION 47The 48.Fn exit 49and 50.Fn _Exit 51functions terminate a process. 52.Pp 53Before termination, 54.Fn exit 55performs the following functions in the order listed: 56.Bl -enum -offset indent 57.It 58Call all functions registered with the 59.Xr __cxa_atexit 3 60function 61(which are typically destructors from the loaded dynamic objects), 62and the functions registered with the 63.Xr atexit 3 64function, in the reverse order of their registration. 65.It 66Flush all open output streams. 67.It 68Close all open streams. 69.El 70.Pp 71The 72.Fn _Exit 73function terminates without calling the functions registered with the 74.Xr atexit 3 75function, and may or may not perform the other actions listed. 76The 77.Fx 78implementation of the 79.Fn _Exit 80function does not call destructors registered with 81.Xr __cxa_atexit 3 , 82does not flush buffers, and does not close streams. 83.Pp 84Both functions make the low-order eight bits of the 85.Fa status 86argument available to a parent process which has called a 87.Xr wait 2 Ns -family 88function. 89.Pp 90The C Standard 91.Pq St -isoC-99 92defines the values 93.Li 0 , 94.Dv EXIT_SUCCESS , 95and 96.Dv EXIT_FAILURE 97as possible values of 98.Fa status . 99Cooperating processes may use other values; 100in a program which might be called by a mail transfer agent, the 101values described in 102.Xr sysexits 3 103may be used to provide more information to the parent process. 104.Pp 105The complete 106.Fa status 107value is avaliable as 108.Va si_status 109member of the 110.Vt siginfo_t 111structure, to the 112.Xr wait6 2 113and 114.Xr sigwaitinfo 2 115callers, and 116.Va SIGCHLD 117signal handlers. 118.Pp 119Calls to the 120.Fn exit 121function are serialized. 122All functions registered by 123.Xr atexit 3 124are executed in the first thread that called 125.Nm exit . 126If any other thread of the process calls 127.Nm exit 128before all registered functions have completed or before the process 129terminates, the thread is blocked until the process terminates. 130The exit status of the process is the 131.Fa status 132argument of the first 133.Nm exit 134call which thread proceeds the atexit handlers. 135.Pp 136Note that 137.Fn exit 138does nothing to prevent bottomless recursion should a function registered 139using 140.Xr atexit 3 141itself call 142.Fn exit . 143Such functions must call 144.Fn _Exit 145instead (although this has other effects as well which may not be desired). 146.Sh RETURN VALUES 147The 148.Fn exit 149and 150.Fn _Exit 151functions 152never return. 153.Sh SEE ALSO 154.Xr _exit 2 , 155.Xr abort2 2 , 156.Xr wait 2 , 157.Xr at_quick_exit 3 , 158.Xr atexit 3 , 159.Xr intro 3 , 160.Xr quick_exit 3 , 161.Xr sysexits 3 , 162.Xr tmpfile 3 163.Sh STANDARDS 164The 165.Fn exit 166and 167.Fn _Exit 168functions conform to 169.St -isoC-99 . 170.Sh HISTORY 171The 172.Fn exit 173function appeared in 174.At v1 . 175