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# system

From cppreference.com
< c‎ | program

Defined in header `<stdlib.h>` |  |
int system( const char *command ); |  |

Calls the host environment's command processor with command parameter. Returns implementation-defined value (usually the value that the invoked program returns).

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

### [edit] Parameters

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

### [edit] Return value

Implementation-defined value. If `command` is NULL, returns nonzero value only if command processor exists.

### [edit] Notes

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

Related POSIX function popen makes the output generated by `command` available to the caller.

### [edit] Example

In this example there is a system call of the unix command ls -l >test.txt:

Run this code

    #include <stdlib.h>

    int main(void) {

        system("ls -l >test.txt");

        return 0;
    }

### [edit] References

- C11 standard (ISO/IEC 9899:2011):

  - 7.22.4.8 The system function (p: 353-354)

- C99 standard (ISO/IEC 9899:1999):

  - 7.20.4.6 The system function (p: 317)

- C89/C90 standard (ISO/IEC 9899:1990):

  - 4.10.4.5 The system function

### [edit] See also

C++ documentation for system

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