Root Directory in Unix-like systems
– Unix abstracts the nature of the tree hierarchy.
– The root directory is denoted by the slash sign (/).
– The root directory has no name, its path is the empty part before the initial directory separator character.
– All file system entries, including mounted file systems, are branches of the root directory.
chroot
– Each process in UNIX-like operating systems has its own idea of the root directory.
– The root directory for most processes is the same as the system’s actual root directory.
– The root directory can be changed by calling the chroot system call.
– Chroot is used to create a secluded environment for running software that requires legacy libraries.
– Chroot is not meant for enhanced security as processes inside can break out.
Super-root
– Some Unix systems support a directory below the root directory.
– Normally, /.. points back to the same inode as /.
– Under MUNIXde, /.. can be changed to point to a super-root directory.
– Super-root allows mounting remote trees.
– It enables accessing the root directory of a remote workstation.
Related uses
– Many Unixes have a directory named /root.
– /root is the home directory of the root superuser.
– On many Mac and iOS systems, the superuser home directory is /var/root.
Other related concepts
– Filesystem Hierarchy Standard (FHS)
– Parent directory
– Working directory
References:
– Root Directory Definition. (techterms.com)
– Root Filesystem Definition by The Linux Information Project. (LInfo.org)
– What chroot() is really for. (LWN.net)
– The Newcastle Connection (PDF) by Brownbridge, David R.; Marshall, Lindsay F.; Randell, Brian
– NFS Illustrated by Brent Callaghan
In a computer file system, and primarily used in the Unix and Unix-like operating systems, the root directory is the first or top-most directory in a hierarchy. It can be likened to the trunk of a tree, as the starting point where all branches originate from. The root file system is the file system contained on the same disk partition on which the root directory is located; it is the filesystem on top of which all other file systems are mounted as the system boots up.
