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─────Run-Time Library───────────────────────────────────────────────────────
 
/* EXEC.C illustrates the different versions of exec including:
 *      _execl           _execle          _execlp          _execlpe
 *      _execv           _execve          _execvp          _execvpe
 *
 * Although EXEC.C can exec any program, you can verify how different
 * versions handle arguments and environment by compiling and
 * specifying the sample program ARGS.C. See SPAWN.C for examples
 * of the similar spawn functions.
 */
 
#include <stdio.h>
#include <conio.h>
#include <process.h>
 
char *my_env[] =                /* Environment for exec?e */
{
    "THIS=environment will be",
    "PASSED=to child by the",
    "SPAWN=functions",
    NULL
};
 
void main()
{
    char *args[4], prog[80];
    int ch;
 
    printf( "Enter name of program to exec: " );
    gets( prog );
    printf( " 1. _execl   2. _execle   3. _execlp   4. _execlpe\n" );
    printf( " 5. _execv   6. _execve   7. _execvp   8. _execvpe\n" );
    printf( "Type a number from 1 to 8 (or 0 to quit): " );
    ch = _getche();
    if( (ch < '1') || (ch > '8') )
        exit( 1 );
    printf( "\n\n" );
 
    /* Arguments for _execv? */
    args[0] = prog;
    args[1] = "exec??";
    args[2] = "two";
    args[3] = NULL;
 
    switch( ch )
    {
        case '1':
            _execl( prog, prog, "_execl", "two", NULL );
            break;
        case '2':
            _execle( prog, prog, "_execle", "two", NULL, my_env );
            break;
        case '3':
            _execlp( prog, prog, "_execlp", "two", NULL );
            break;
        case '4':
            _execlpe( prog, prog, "_execlpe", "two", NULL, my_env );
            break;
        case '5':
            _execv( prog, args );
            break;
        case '6':
            _execve( prog, args, my_env );
            break;
        case '7':
            _execvp( prog, args );
            break;
        case '8':
            _execvpe( prog, args, my_env );
            break;
        default:
            break;
    }
 
    /* This point is reached only if exec fails. */
    printf( "\nProcess was not execed." );
    exit( 0 );
}
                                    -♦-