allow null defaults in $( ... $) lookups

[unix-history] / usr / src / usr.sbin / chroot / chroot.c

/*
* Copyright (c) 1988, 1993
*      The Regents of the University of California.  All rights reserved.
*
* %sccs.include.redist.c%
*/

#ifndef lint
static char copyright[] =
"@(#) Copyright (c) 1988, 1993\n\
       The Regents of the University of California.  All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)chroot.c    8.1 (Berkeley) %G%";
#endif /* not lint */

#include <sys/types.h>

#include <err.h>
#include <errno.h>
#include <paths.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

void usage __P((void));

int
main(argc, argv)
       int argc;
       char *argv[];
{
       int ch;
       char *shell;

       while ((ch = getopt(argc, argv, "")) != EOF)
               switch(ch) {
               case '?':
               default:
                       usage();
               }
       argc -= optind;
       argv += optind;

       if (argc < 1)
               usage();

       if (chdir(argv[0]) || chroot("."))
               err(1, "%s", argv[0]);

       if (argv[1]) {
               execvp(argv[1], &argv[1]);
               err(1, "%s", argv[1]);
       }

       if (!(shell = getenv("SHELL")))
               shell = _PATH_BSHELL;
       execlp(shell, shell, "-i", NULL);
       err(1, "%s", shell);
       /* NOTREACHED */
}

void
usage()
{
       (void)fprintf(stderr, "usage: chroot newroot [command]\n");
       exit(1);
}