system(3C)						   Standard C Library Functions 						system(3C)

NAME

       system - 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 conforms 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 wait-
       ing 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 signal 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  processes, 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 insufficient 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	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Unsafe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       ksh(1), sh(1), popen(3C), posix_spawn(3C), wait(3C), waitpid(3C), attributes(5), standards(5)

SunOS 5.11							    14 Dec 2006 							system(3C)