Appendix H. Important System Directories

Sysadmins and anyone else writing administrative scripts should be intimately familiar with the following system directories.

• /bin

  Binaries (executables). Basic system programs and utilities (such as bash).

• /usr/bin [1]

  More system binaries.

• /usr/local/bin

  Miscellaneous binaries local to the particular machine.

• /sbin

  System binaries. Basic system administrative programs and utilities (such as fsck).

• /usr/sbin

  More system administrative programs and utilities.

• /etc

  Et cetera. Systemwide configuration scripts.

  Of particular interest are the /etc/fstab (filesystem table), /etc/mtab (mounted filesystem table), and the /etc/inittab files.

• /etc/rc.d

  Boot scripts, on Red Hat and derivative distributions of Linux.

• /usr/share/doc

  Documentation for installed packages.

• /usr/man

  The systemwide manpages.

• /dev

  Device directory. Entries (but not mount points) for physical and virtual devices. See Chapter 27.

• /proc

  Process directory. Contains information and statistics about running processes and kernel parameters. See Chapter 27.

• /sys

  Systemwide device directory. Contains information and statistics about device and device names. This is newly added to Linux with the 2.6.X kernels.

• /mnt

  Mount. Directory for mounting hard drive partitions, such as /mnt/dos, and physical devices. In newer Linux distros, the /media directory has taken over as the preferred mount point for I/O devices.

• /media

  In newer Linux distros, the preferred mount point for I/O devices, such as CD/DVD drives or USB flash drives.

• /var

  Variable (changeable) system files. This is a catchall "scratchpad" directory for data generated while a Linux/UNIX machine is running.

• /var/log

  Systemwide log files.

• /var/spool/mail

  User mail spool.

• /lib

  Systemwide library files.

• /usr/lib

  More systemwide library files.

• /tmp

  System temporary files.

• /boot

  System boot directory. The kernel, module links, system map, and boot manager reside here.

  Altering files in this directory may result in an unbootable system.