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CHROOT(2)                   BSD System Calls Manual                  CHROOT(2)

     chroot -- change root directory

     #include <unistd.h>

     chroot(const char *dirname);

     Dirname is the address of the pathname of a directory, terminated by an
     ASCII NUL.  Chroot() causes dirname to become the root directory, that
     is, the starting point for path searches of pathnames beginning with `/'.

     In order for a directory to become the root directory a process must have
     execute (search) access for that directory.

     If the program is not currently running with an altered root directory,
     it should be noted that chroot() has no effect on the process's current

     If the program is already running with an altered root directory, the
     process's current directory is changed to the same new root directory.
     This prevents the current directory from being further up the directory
     tree than the altered root directory.

     This call is restricted to the super-user.

     Upon successful completion, a value of 0 is returned.  Otherwise, a value
     of -1 is returned and errno is set to indicate an error.

     Chroot() will fail and the root directory will be unchanged if:

     [ENOTDIR]          A component of the path name is not a directory.

     [ENAMETOOLONG]     A component of a pathname exceeded {NAME_MAX} charac-ters, characters,
                        ters, or an entire path name exceeded {PATH_MAX} char-acters. characters.

     [ENOENT]           The named directory does not exist.

     [EACCES]           Search permission is denied for any component of the
                        path name.

     [ELOOP]            Too many symbolic links were encountered in translat-ing translating
                        ing the pathname.

     [EFAULT]           Path points outside the process's allocated address

     [EIO]              An I/O error occurred while reading from or writing to
                        the file system.


     There are ways for a root process to escape from the chroot jail.

     The chroot() function call appeared in 4.2BSD.

4.2 Berkeley Distribution        June 4, 1993        4.2 Berkeley Distribution