The file system hierarchy
All files on a Linux system are stored on file systems which are organized into a single inverted tree of directories, know as a file system hierarchy.In the inverted tree, root lies at the top and the branches of directories and sub-directories stretch below the root.
Figure: Significant file system directories (RHEL 7)
Here, the directories ‘/’ is the root directory which lies at the top of file system hierarchy. The ‘/’ character is also used as a directory separator in the file name, for example ‘/etc’ is a sub-directory of ‘/’ directory.
Important RHEL (Red Hat Enterprise Linux) directories
|/usr||Installed software, shared libraries, include files, and static read-only program data. Important subdirectories include:-
* /usr/bin: User commands.
* /usr/sbin: System administration commands.
* /usr/local: Locally customized software.
|/etc||Configuration files specific to this system.|
|/var||Files that dynamically change (e.g. databases, cache directories, log files, printer spooled documents, and website content) may be found under /var.|
|/run||Run-time data for processes started since the last boot. This includes process ID files and lock files, among other things. The contents of this directory are recreated on reboot.|
|/home||Home directories where regular users store their personal data and configuration files.|
|/root||Home directory for the administrative superuser, root.|
|/tmp||A world-writable space for temporary files. Files more than 10 days are automatically be deleted from that directory. Another temporary directory exists at /var/tmp, in which files that have not been accessed,changed, or modified in more than 30 days are deleted automatically.|
|/boot||Files needed in order to start the boot process.|
|/dev||Contains special device files which are used by the system to access hardware.|
In RHEL Linux 7, Four oulder directories in ‘/’ now have identical contents as their counterparts located in /usr:
– /bin and /usr/bin
– /sbin and /usr/sbin
– /lib and /usr/lib
– /lib64 and /usr/lib64
In older versions of RHEL, these were distinct directories containing different sets of files. In RHEL 7, the directories in ‘/’ are symbolic links to the matching directories in /usr.
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