system, _wsystem

[アーティクル]
06/05/2017

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Executes a command.

Important

This API cannot be used in applications that execute in the Windows Runtime. For more information, see CRT functions not supported with /ZW.

Syntax

int system(  
   const char *command   
);  
int _wsystem(  
   const wchar_t *command   
);

Parameters

command
The command to be executed.

Return Value

If command is NULL and the command interpreter is found, returns a nonzero value. If the command interpreter is not found, returns 0 and sets errno to ENOENT. If command is not NULL, system returns the value that is returned by the command interpreter. It returns the value 0 only if the command interpreter returns the value 0. A return value of – 1 indicates an error, and errno is set to one of the following values:

E2BIG
The argument list (which is system-dependent) is too big.

ENOENT
The command interpreter cannot be found.

ENOEXEC
The command-interpreter file cannot be executed because the format is not valid.

ENOMEM
Not enough memory is available to execute command; or available memory has been corrupted; or a non-valid block exists, which indicates that the process that's making the call was not allocated correctly.

See _doserrno, errno, _sys_errlist, and _sys_nerr for more information about these return codes.

Remarks

The system function passes command to the command interpreter, which executes the string as an operating-system command. system uses the COMSPEC and PATH environment variables to locate the command-interpreter file CMD.exe. If command is NULL, the function just checks whether the command interpreter exists.

You must explicitly flush—by using fflush or _flushall—or close any stream before you call system.

_wsystem is a wide-character version of system; the command argument to _wsystem is a wide-character string. These functions behave identically otherwise.

Generic-Text Routine Mappings

TCHAR.H routine	_UNICODE & _MBCS not defined	_MBCS defined	_UNICODE defined
`_tsystem`	`system`	`system`	`_wsystem`

Requirements

Routine	Required header
`system`	<process.h> or <stdlib.h>
`_wsystem`	<process.h> or <stdlib.h> or <wchar.h>

For additional compatibility information, see Compatibility.

Example

This example uses system to TYPE a text file.

// crt_system.c  
  
#include <process.h>  
  
int main( void )  
{  
   system( "type crt_system.txt" );  
}

Input: crt_system.txt

Line one.  
Line two.

Output

Line one.  
Line two.

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