This version of this document is no longer maintained. For the latest documentation, see http://www.qnx.com/developers/docs.

daemon()

Run a process in the background

Synopsis:

#include <stdlib.h>

int daemon( int nochdir, 
            int noclose );

Arguments:

nochdir: If this argument is 0, the current working directory is changed to the root directory (/).
noclose: If this argument is 0, standard input, standard output, and standard error are redirected to /dev/null.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

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

This function calls fork() and setsid().

The controlling terminal behaves as in Unix System V, Release 4. An open() on a terminal device not already associated with another session causes the device to become the controlling terminal for that process.

Returns:

Zero for success, or -1 if an error occurs (errno is set).

Classification:

Legacy Unix

Safety:
Cancellation point	No
Interrupt handler	No
Signal handler	Yes
Thread	No

Caveats:

Currently, daemon() is supported only in single-threaded applications. If you create a thread and then call daemon(), the function returns -1 and sets errno to ENOSYS.