system—execute command string #include <stdlib.h>
int system(char *s);
int _system_r(void *reent, char *s);
Description
Use system to pass a command string *s to /bin/sh on
your system, and wait for it to finish executing.
Use “system(NULL)” to test whether your system has /bin/sh
available.
The alternate function _system_r is a reentrant version. The
extra argument reent is a pointer to a reentrancy structure.
Returns
system(NULL) returns a non-zero value if /bin/sh is available, and
0 if it is not.
With a command argument, the result of system is the exit status
returned by /bin/sh.
Portability
system, but leaves the nature and effects of a
command processor undefined. ANSI C does, however, specify that
system(NULL) return zero or nonzero to report on the existence of
a command processor.
POSIX.2 requires system, and requires that it invoke a sh.
Where sh is found is left unspecified.
Supporting OS subroutines required: _exit, _execve, _fork_r,
_wait_r.