system(3C) Standard C Library Functions system(3C)NAMEsystem - issue a shell command
SYNOPSIS
#include <stdlib.h>
int system(const char *string);
DESCRIPTION
The system() function causes string to be given to the shell as input,
as if string had been typed as a command at a terminal. The invoker
waits until the shell has completed, then returns the exit status of
the shell in the format specified by waitpid(3C).
If string is a null pointer, system() checks if the shell exists and is
executable. If the shell is available, system() returns a non-zero
value; otherwise, it returns 0. The standard to which the caller con‐
forms determines which shell is used. See standards(5).
The system() function sets the SIGINT and SIGQUIT signals to be
ignored, and blocks the SIGCHLD signal for the calling thread, while
waiting for the command to terminate. The system() function does not
affect the termination status of any child of the calling processes
other than the process it creates.
The termination status of the process created by the system() function
is not affected by the actions of other threads in the calling process
(it is invisible to wait(3C)) or by the disposition of the SIGCHLD sig‐
nal in the calling process, even if it is set to be ignored. No SIGCHLD
signal is sent to the process containing the calling thread when the
command terminates.
RETURN VALUES
The system() function executes posix_spawn(3C) to create a child
process running the shell that in turn executes the commands in string.
If posix_spawn() fails, system() returns −1 and sets errno to indicate
the error; otherwise the exit status of the shell is returned.
ERRORS
The system() function may set errno values as described by fork(2), in
particular:
EAGAIN A resource control or limit on the total number of pro‐
cesses, tasks or LWPs under execution by a single user,
task, project, or zone has been exceeded, or the total
amount of system memory available is temporarily insuffi‐
cient to duplicate this process.
ENOMEM There is not enough swap space.
EPERM The {PRIV_PROC_FORK} privilege is not asserted in the
effective set of the calling process.
USAGE
The system() function manipulates the signal handlers for SIGINT and
SIGQUIT. It is therefore not safe to call system() in a multithreaded
process, since some other thread that manipulates these signal handlers
and a thread that concurrently calls system() can interfere with each
other in a destructive manner. If, however, no such other thread is
active, system() can safely be called concurrently from multiple
threads. See popen(3C) for an alternative to system() that is thread-
safe.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Committed │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │Unsafe │
├─────────────────────────────┼─────────────────────────────┤
│Standard │See standards(5). │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOksh(1), sh(1), popen(3C), posix_spawn(3C), wait(3C), waitpid(3C),
attributes(5), standards(5)SunOS 5.11 14 Dec 2006 system(3C)
