freebsd man page for system

SYSTEM(3)						   BSD Library Functions Manual 						 SYSTEM(3)

NAME
     system -- pass a command to the shell

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <stdlib.h>

     int
     system(const char *string);

DESCRIPTION
     The system() function hands the argument string to the command interpreter sh(1).	The calling process waits for the shell to finish execut-
     ing the command, ignoring SIGINT and SIGQUIT, and blocking SIGCHLD.

     If string is a NULL pointer, system() will return non-zero if the command interpreter sh(1) is available, and zero if it is not.

RETURN VALUES
     The system() function returns the exit status of the shell as returned by waitpid(2), or -1 if an error occurred when invoking fork(2) or
     waitpid(2).  A return value of 127 means the execution of the shell failed.

SEE ALSO
     sh(1), execve(2), fork(2), waitpid(2), popen(3)

STANDARDS
     The system() function conforms to ISO/IEC 9899:1990 (``ISO C90'') and is expected to be IEEE Std 1003.2 (``POSIX.2'') compatible.

BSD
								   June 4, 1993 							       BSD