Content-type: text/html Man page of system

system

Section: C Library Functions (3)
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NAME

system - Executes a shell command  

LIBRARY

Standard C Library (libc.so, libc.a)  

SYNOPSIS

#include <stdlib.h>

int system(
        const char *string);  

STANDARDS

Interfaces documented on this reference page conform to industry standards as follows:

system():  XPG4, XPG4-UNIX

Refer to the standards(5) reference page for more information about industry standards and associated tags.  

PARAMETERS

Specifies a valid sh shell command.

If string is NULL (0), the system() function tests the accessibility of the sh command interpreter.
If string is not NULL, the system() function passes the parameter to the sh command, which interprets string as a command and executes it.
 

DESCRIPTION

The system() function passes the string parameter to the sh command, which interprets string as a command and executes it.

The system() function invokes the fork() function to create a child process that in turn uses the exec function to run sh, which interprets the shell command contained in the string parameter. The current process waits until the shell has completed before returning.  

RETURN VALUES

If the string parameter is NULL, the system() function returns 0 if it is unable to access the command interpreter or a non-zero value if sh is accessible.

If the string parameter is not NULL, upon successful completion by sh, the system() function returns the exit status of the shell process in the form that wait(2) returns. Otherwise, the system() function returns a value of -1 and sets errno to indicate the error.

Exit status 127 indicates that the shell could not be executed.

Note that the exit status should only be interpreted using the macros described in wait(2) and defined in the sys/wait.h header file.  

ERRORS

The system() function sets errno to the specified values for the following conditions: The status of the child process created by system() is no longer available.

In addition, the system() function may set errno values as described by fork().  

RELATED INFORMATION

Functions: exec(2), exit(2), fork(2), wait(2)

Commands: sh(1)

Standards: standards(5) delim off


 

Index

NAME
LIBRARY
SYNOPSIS
STANDARDS
PARAMETERS
DESCRIPTION
RETURN VALUES
ERRORS
RELATED INFORMATION

This document was created by man2html, using the manual pages.
Time: 02:40:47 GMT, October 02, 2010