system
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NAME
system - execute a shell command
SYNOPSIS
#include <stdlib.h>
int system (const char * string);
DESCRIPTION
system() executes a command specified in string by calling
/bin/sh -c string, and returns after the command has been
completed. During execution of the command, SIGCHLD will
be blocked, and SIGINT and SIGQUIT will be ignored.
RETURN VALUE
The value returned is 127 if the execve() call for /bin/sh
fails, -1 if there was another error and the return code
of the command otherwise.
If the value of string is NULL, system() returns nonzero
if the shell is available, and zero if not.
system() does not affect the wait status of any other
children.
CONFORMS TO
ANSI C, POSIX.1, proposed POSIX.2, BSD 4.3
BUGS
Do not use system() from a program with suid or sgid priv-
ileges, because strange values for some environment vari-
ables might be used to subvert system integrity. Use the
exec(2) family of functions instead, but not execlp(2) or
execvp(2).
The check for the availability of /bin/sh is not actually
performed; it is always assumed to be available.
It is possible for the shell command to return 127, so
that code is not a sure indication that the execve() call
failed; check errno to make sure.
SEE ALSO
sh(1), exec(2), signal(2)
Hurricane Electric Internet Services
Copyright (C) 1998
Hurricane Electric.
All Rights Reserved.