system(3C) system(3C)
NAME
system - issue a shell command
SYNOPSIS
#include <stdlib.h>
int system(const char *string);
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 conforms determines which shell is used. See standards(5).
The system() function executes vfork(2) to create a child process that in turn invokes one of the exec family of functions (see exec(2)) on
the shell to execute string. If vfork() or the exec function fails, system() returns -1 and sets errno to indicate the error.
The system() function fails if:
EAGAIN The system-imposed limit on the total number of processes under execution by a single user would be exceeded.
EINTR The system() function was interrupted by a signal.
ENOMEM The new process requires more memory than is available.
USAGE
The system() function manipulates the signal handlers for SIGINT, SIGQUIT, and SIGCHLD. It is therefore not safe to call system() in a mul-
tithreaded process, since some other thread that manipulates these signal handlers and a thread that concurrently calls system() can inter-
fere 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.
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Interface Stability |Standard |
+-----------------------------+-----------------------------+
|MT-Level |Unsafe |
+-----------------------------+-----------------------------+
ksh(1), sh(1), exec(2), vfork(2), popen(3C), waitpid(3C), attributes(5), standards(5)
18 Dec 2003 system(3C)