| SYSTEM(3) | MidnightBSD Library Functions Manual | SYSTEM(3) |
system — pass a
command to the shell
Standard C Library (libc, -lc)
#include
<stdlib.h>
int
system(const
char *string);
The
system()
function hands the argument string to the command
interpreter sh(1). The
calling process waits for the shell to finish executing 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.
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.
sh(1), execve(2), fork(2), waitpid(2), popen(3), posix_spawn(3)
The system() function conforms to
ISO/IEC 9899:1990 (“ISO C90”)
and is expected to be IEEE Std 1003.2
(“POSIX.2”) compatible.
The system() function is easily misused in
a manner that enables a malicious user to run arbitrary command, because all
meta-characters supported by
sh(1) would be honored. User
supplied parameters should always be carefully santized before they appear
in string.
| July 25, 2015 | midnightbsd-3.1 |