NAME¶

std::system - std::system

Synopsis¶

Defined in header <cstdlib>
int system( const char* command );

Calls the host environment's command processor (e.g. /bin/sh, cmd.exe, command.com)
with the parameter command. Returns an implementation-defined value (usually the
value that the invoked program returns).

If command is a null pointer, checks if the host environment has a command processor
and returns a nonzero value if and only if the command processor exists.

Parameters¶

character string identifying the command to be run in the command
command - processor. If a null pointer is given, command processor is checked for
existence

Return value¶

Implementation-defined value. If command is a null pointer, returns a nonzero value
if and only if the command processor exists.

Notes¶

On POSIX systems, the return value can be decomposed using WEXITSTATUS and WSTOPSIG

The related POSIX function popen makes the output generated by command available to
the caller.

An explicit flush of std::cout is also necessary before a call to std::system, if
the spawned process performs any screen I/O.

Example¶

// Run this code

#include <cstdlib>
#include <fstream>
#include <iostream>

int main()
{
std::system("ls -l >test.txt"); // execute the UNIX command "ls -l >test.txt"
std::cout << std::ifstream("test.txt").rdbuf();
}

Possible output:¶

total 16
-rwxr-xr-x 1 2001 2000 8859 Sep 30 20:52 a.out
-rw-rw-rw- 1 2001 2000 161 Sep 30 20:52 main.cpp
-rw-r--r-- 1 2001 2000 0 Sep 30 20:52 test.txt

See also¶