NAME

daemon - run in the background

SYNOPSIS

#include <unistd.h>

int daemon(int nochdir, int noclose);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

daemon(): _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)

DESCRIPTION

The daemon() function is for programs wishing to detach themselves from the controlling terminal and run in the background as system daemons.

Unless the argument nochdir is nonzero, daemon() changes the current working directory to the root ("/").

Unless the argument noclose is nonzero, daemon() will redirect standard input, standard output and standard error to /dev/null.

RETURN VALUE

(This function forks, and if the fork(2) succeeds, the parent calls _exit(2), so that further errors are seen by the child only.) On success zero will be returned. If an error occurs, daemon() returns -1 and sets the global variable errno to any of the errors specified for the fork(2) and setsid(2).

CONFORMING TO

Not in POSIX.1-2001. A similar function appears on the BSDs. The daemon() function first appeared in 4.4BSD.

NOTES

The glibc implementation can also return -1 when /dev/null exists but is not a character device with the expected major and minor numbers. In this case errno need not be set.

SEE ALSO

fork(2), setsid(2)

COLOPHON

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