SYSTEM(3)

SYSTEM(3) | 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 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 is available, or zero if none is available. Otherwise, system() returns the termination status of the shell in the format specified by waitpid(2).

# RETURN VALUES

If a child process cannot be created, or the termination status of the shell cannot be obtained, system() returns -1 and sets errno to indicate the error. If execution of the shell fails, system() returns the termination status for a program that terminates with a call of exit(127).

# SEE ALSO

sh(1), execve(2), waitpid(2), popen(3), shquote(3)

# STANDARDS

The system() function conforms to ANSI X3.159-1989 (“ANSI C89”) and IEEE Std 1003.2-1992 (“POSIX.2”).

# CAVEATS

Never supply the system() function with a command containing any part of an unsanitized user-supplied string. Shell meta-characters present will be honored by the sh(1) command interpreter.

August 2, 2007 | NetBSD 7.1