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.\" 33.Dd July 24, 2024 34.Dt EXIT 3 35.Os 36.Sh NAME 37.Nm exit , _Exit 38.Nd perform normal program termination 39.Sh LIBRARY 40.Lb libc 41.Sh SYNOPSIS 42.In stdlib.h 43.Ft void 44.Fn exit "int status" 45.Ft void 46.Fn _Exit "int status" 47.Sh DESCRIPTION 48The 49.Fn exit 50and 51.Fn _Exit 52functions terminate a process. 53.Pp 54Before termination, 55.Fn exit 56performs the following functions in the order listed: 57.Bl -enum -offset indent 58.It 59Call all functions registered with the 60.Xr __cxa_atexit 3 61function 62(which are typically destructors from the loaded dynamic objects), 63and the functions registered with the 64.Xr atexit 3 65function, in the reverse order of their registration. 66.It 67Flush all open output streams. 68.It 69Close all open streams. 70.El 71.Pp 72The 73.Fn _Exit 74function terminates without calling the functions registered with the 75.Xr atexit 3 76function, and may or may not perform the other actions listed. 77The 78.Fx 79implementation of the 80.Fn _Exit 81function does not call destructors registered with 82.Xr __cxa_atexit 3, 83does not flush buffers, and does not close streams. 84.Pp 85Both functions make the low-order eight bits of the 86.Fa status 87argument available to a parent process which has called a 88.Xr wait 2 Ns -family 89function. 90.Pp 91The C Standard 92.Pq St -isoC-99 93defines the values 94.Li 0 , 95.Dv EXIT_SUCCESS , 96and 97.Dv EXIT_FAILURE 98as possible values of 99.Fa status . 100Cooperating processes may use other values; 101in a program which might be called by a mail transfer agent, the 102values described in 103.Xr sysexits 3 104may be used to provide more information to the parent process. 105.Pp 106The complete 107.Fa status 108value is avaliable as 109.Va si_status 110member of the 111.Vt siginfo_t 112structure, to the 113.Xr wait6 2 114and 115.Xr sigwaitinfo 2 116callers, and 117.Va SIGCHLD 118signal handlers. 119.Pp 120Calls to the 121.Fn exit 122function are serialized. 123All functions registered by 124.Xr atexit 3 125are executed in the first thread that called 126.Nm exit . 127If any other thread of the process calls 128.Nm exit 129before all registered functions have completed or before the process 130terminates, the thread is blocked until the process terminates. 131The exit status of the process is the 132.Fa status 133argument of the first 134.Nm exit 135call which thread proceeds the atexit handlers. 136.Pp 137Note that 138.Fn exit 139does nothing to prevent bottomless recursion should a function registered 140using 141.Xr atexit 3 142itself call 143.Fn exit . 144Such functions must call 145.Fn _Exit 146instead (although this has other effects as well which may not be desired). 147.Sh RETURN VALUES 148The 149.Fn exit 150and 151.Fn _Exit 152functions 153never return. 154.Sh SEE ALSO 155.Xr _exit 2 , 156.Xr abort2 2 , 157.Xr wait 2 , 158.Xr at_quick_exit 3 , 159.Xr atexit 3 , 160.Xr intro 3 , 161.Xr quick_exit 3 , 162.Xr sysexits 3 , 163.Xr tmpfile 3 164.Sh STANDARDS 165The 166.Fn exit 167and 168.Fn _Exit 169functions conform to 170.St -isoC-99 . 171.Sh HISTORY 172The 173.Fn exit 174function appeared in 175.At v1 . 176