Mac Developer Library Developer


This manual page is part of Xcode Tools version 5.0

To obtain these tools:

If you are running a version of Xcode Tools other than 5.0, view the documentation locally:

  • In Xcode

  • In Terminal, using the man(1) command

Reading manual pages

Manual pages are intended as a quick reference for people who already understand a technology.

  • To learn how the manual is organized or to learn about command syntax, read the manual page for manpages(5).

  • For more information about this technology, look for other documentation in the Apple Developer Library.

  • For general information about writing shell scripts, read Shell Scripting Primer.

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 begin-ning beginning
     ning 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 directory.

     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} characters, or an entire path name
                        exceeded {PATH_MAX} 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 translating the pathname.

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

     [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

Reporting Problems

The way to report a problem with this manual page depends on the type of problem:

Content errors
Report errors in the content of this documentation with the feedback links below.
Bug reports
Report bugs in the functionality of the described tool or API through Bug Reporter.
Formatting problems
Report formatting mistakes in the online version of these pages with the feedback links below.