Manage Files on Linux

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Linux uses a unified directory tree, meaning every partition, removable disk, network file share, other storage device is accessible as a directory in a single directory tree (or filesystem).

• this filesystem is structured
  • some directories have a specific purpose
• all starts at the root directory /

User Files vs. System Files

System files are files that control how the computer operates.

• includes:
  • system startup scripts
  • program files
    • both binary files and scripts
  • program support files
    • e.g., fonts and icons
  • configuration files
    • define how the system works
  • configuration files for server services and other daemons
  • data storage for system programs
  • system log files
• system files are normally owned by root
  • to restrict ordinary users from accessing

Filesystem Hierarchy Standard (FHS)

Filesystem Hierarchy Standard (FHS) is a system of standardization for Linux system files.

• some Unix-like OSs also follow FHS
• FHS distinguishes two kinds of files:
  • Sharable files
    • are files that may be reasonable shared between computers
    • e.g., user data files and program binary files
  • Unsharable files
    • contain system-specific information
    • e.g., configuration files
• FHS also distinguishes between:
  • Static files
    • doesn’t change except through direct intervention by the system administrator
    • e.g., program executables
  • Variable files
    • files that may change without direct intervention by system administrator
    • may change by:
      • users
      • automated scripts
      • servers
    • e.g., home directories

	Shareable	Unshareable
Static	/usr, /opt	/etc, /root
Variable	/home, /var/mail	/var/run, /var/lock

• Find FHS web page at linuxfoundation.org/collaborate/workgroups/lsb/fhs

Important Directories

Directory	Kind	Purpose
/	System	Root directory. All files appear in this directory or subdirectories of it.
/etc	System	Holds system configuration files
/boot	System	Holds important boot files (e.g., Linux kernel, initial RAM disk, boot loader config files)
/bin	System	Holds program files that are critical for normal operation and that ordinary users may run.
/sbin	System	Holds program files that are critical for normal operation and that ordinary users seldom run.
/lib	System	Holds libraries—code used by many other programs—that are critical for basic system operation.
/usr	System	Holds programs and data used in normal system operation but that are not critical for a bare bones boot of the system. Split into subdirectories that mirror part of the root organization (i.e., /user/bin, /usr/sbin, /usr/lib, etc.)
/home	User	Hold’s users’ home directories.
/root	System	The root user’s home directory.
/var	System	Holds miscellaneous transient files (e.g., log files, print spool files). /var/tmp holds temporary files, but they should not be deleted upon computer reboot.
/tmp	User	Holds temporary files. May be deleted when the computer reboots.
/mnt	User	The traditional mount point for removable media; sometimes split into subdirectories for each mounted filesystem.
/media	User	The new mount point for removable media; typically split into subdirectories for each mounted filesystem.
/dev	System	Holds device files, which provide low-level access to hardware.
/run	System	Information about the running system.