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:
| 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.