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 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.

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.