chroot, fchroot - change root directory
int chroot(const char *path);
int fchroot(int fildes);
The chroot() and fchroot() functions cause a directory to
become the root directory, the starting point for path
searches for path names beginning with / (slash). The user's
working directory is unaffected by the chroot() and
The path argument points to a path name naming a directory.
The fildes argument to fchroot() is the open file descriptor
of the directory which is to become the root.
The effective user ID of the process must be super-user to
change the root directory. While it is always possible to
change to the system root using the fchroot() function, it
is not guaranteed to succeed in any other case, even should
fildes be valid in all respects.
The ".." entry in the root directory is interpreted to mean
the root directory itself. Therefore, ".." cannot be used to
access files outside the subtree rooted at the root direc-
tory. Instead, fchroot() can be used to reset the root to a
directory that was opened before the root directory was
Upon successful completion, 0 is returned. Otherwise, -1 is
returned, the root directory remains unchanged, and errno is
set to indicate the error.
The chroot() function will fail if:
Search permission is denied for a component of the
path prefix of dirname, or search permission is denied
for the directory referred to by dirname.
EBADF The descriptor is not valid.
The path argument points to an illegal address.
The fchroot() function attempted to change to a direc-
tory the is not the system root and external cir-
cumstances do not allow this.
EINTR A signal was caught during the execution of the
EIO An I/O error occurred while reading from or writing to
the file system.
ELOOP Too many symbolic links were encountered in translat-
The length of the path argument exceeds PATH_MAX, or
the length of a path component exceeds NAME_MAX while
_POSIX_NO_TRUNC is in effect.
The named directory does not exist or is a null path-
The path argument points to a remote machine and the
link to that machine is no longer active.
Any component of the path name is not a directory.
EPERM The effective user of the calling process is not
The only use of fchroot() that is appropriate is to change
back to the system root.
Man(1) output converted with