daemon()
Run a process in the background
See fork() to understand the implications of using daemon() instead of procmgr_daemon().
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.
If daemon() is called with a noclose value of 0 and fails, then the states of file descriptors 0, 1, and 2 (STDIN_FILENO, STDOUT_FILENO, and STDERR_FILENO) are undefined.
If you are using the High Availability Manager (HAM), daemon() notifies the HAM of the new process change. If the calling process is being monitored, the HAM switches to monitor the new process that daemon() creates. For more information, see the High Availability Framework Developer's Guide.
Returns:
Zero for success, or -1 if an error occurs (errno is set).
Errors:
- EAGAIN
- Insufficient resources are available to create the child process. For example, you might have exceeded the maximum number of processes permitted; see the RLIMIT_NPROC resource for getrlimit().
- ENOMEM
- The process requires more memory than the system is able to supply.
- EPERM
- One of the following occurred:
- The calling process doesn't have PROCMGR_AID_FORK or PROCMGR_AID_PGRP abilities; see Abilities in the System Security Guide.
- The calling process's priority is above the permitted range.
- The process group ID of a process other than the calling process matches the process ID of the calling process. This is unlikely to occur.
Classification:
| Safety: | |
|---|---|
| Cancellation point | No |
| Signal handler | Yes |
| Thread | See fork() for details |