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system, _wsystem

Execute a command.

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

Parameter

command
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
Argument list (which is system dependent) is too big.
ENOENT
Command interpreter cannot be found.
ENOEXEC
Command-interpreter file has invalid format and is not executable.
ENOMEM
Not enough memory is available to execute command; or available memory has been corrupted; or invalid block exists, indicating that process making call was not allocated properly.

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

Remarks

The system function passes command to the command interpreter, which executes the string as an operating-system command. system refers to the COMSPEC and PATH environment variables that locate the command-interpreter file (the file named CMD.EXE in Windows NT). If command is NULL, the function simply checks to see whether the command interpreter exists.

You must explicitly flush (using fflush or _flushall) or close any stream before calling 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 Compatibility
system <process.h> or <stdlib.h> ANSI, Win 98, Win Me, Win NT, Win 2000, Win XP
_wsystem <process.h> or <stdlib.h> or <wchar.h> Win NT, Win 2000, Win XP

For additional compatibility information, see Compatibility in the Introduction.

Libraries

All versions of the C run-time libraries.

Example

This program 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.

See Also

Process and Environment Control Routines | _exec Functions | exit | _flushall | _spawn Functions | Run-Time Routines and .NET Framework Equivalents

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