W3cubDocs

system

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

Calls the host environment's command processor 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

command

character string identifying the command to be run in the 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.

Example

In this example there is a system call of the unix command date +%A and a system call to (possibly installed) gcc compiler with command-line argument (--version):

#include <stdlib.h>
 
int main(void) {
    system("date +%A");
    system("gcc --version");
}

Possible output:

Wednesday
gcc (GCC) 11.2.0
...

References

C17 standard (ISO/IEC 9899:2018):

7.22.4.8 The system function (p: 257)

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):