system(3)system(3)NAMEsystem - Execute a shell command
SYNOPSIS
#include <stdlib.h>
int system(
const char *string );
LIBRARY
Standard C Library (libc)
STANDARDS
Interfaces documented on this reference page conform to industry stan‐
dards 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 accessi‐
bility of the sh command interpreter.
If string is not NULL, the system() function passes the parame‐
ter 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. See sh(1) to
determine which command interpreter is defined by sh on your system.
The system() function invokes the fork() function to create a child
process that in turn uses theexec 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 thesys/wait.h header file.
ERRORS
The system() function sets errno to the specified values for the fol‐
lowing 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().
SEE ALSO
Functions: exec(2), exit(2), fork(2), wait(2)
Commands: sh(1)
Standards: standards(5)system(3)
