daemon(3C) Standard C Library Functions daemon(3C)NAMEdaemon - basic daemonization function
SYNOPSIS
#include <stdlib.h>
int daemon(int nochdir, int noclose);
DESCRIPTION
The daemon() function provides a means for applications to run in the
background.
This function ensures that the process calling this function:
o runs in the background
o detaches from the controlling terminal
o forms a new process group
o is not a session group leader.
The arguments to this function are treated as boolean variables and are
evaluated using negative logic.
If the nochdir argument is zero the working directory will be changed
to the root directory (/); otherwise it will not be.
If the noclose argument is zero the descriptors 0, 1, and 2 (normally
corresponding to standard input, output and error output, depending on
the application) will be redirected to /dev/null; otherwise they will
not be.
RETURN VALUES
Upon successful completion, daemon() returns 0. Otherwise it returns -1
and sets errno to the values specified for fork(2), setsid(2), open(2),
and dup(2).
If daemon() is called with noclose set to 0 and fails to redirect
descriptors 0, 1, and 2 to /dev/null, those descriptors are not guaran‐
teed to be the same as before the call.
EXAMPLES
Example 1 Using daemon to run a process in the background.
The main() function of a network server could look like this:
int background; /* background flag */
/* Load and verify the configuration. */
/* Go into background. */
if (background && daemon(0, 0) < 0)
err(1, "daemon");
/* Process requests here. */
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Committed │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │Async-Signal-Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOIntro(2), dup(2), fork(2), open(2), setsid(2), attributes(5)SunOS 5.11 15 Sep 2009 daemon(3C)
