NAME
system —
pass a command to the shell
LIBRARY
library “libc”
SYNOPSIS
#include
<stdlib.h>
int
system(const
char *string);
DESCRIPTION
Thesystem()
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.
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), posix_spawn(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.
SECURITY CONSIDERATIONS
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.