Appendix I. Important System Directories
Appendix I. Important System Directories
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Appendix I. 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 [148]

    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 29, /dev and /proc.

  • /proc

    Process directory. Contains information and statistics about running processes and kernel parameters. See Chapter 29, /dev and /proc.

  • /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.

    Warning

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


[148] Some early UNIX systems had a fast, small-capacity fixed disk (containing /, the root partition), and a second drive which was larger, but slower (containing /usr and other partitions). The most frequently used programs and utilities therefore resided on the small-but-fast drive, in /bin, and the others on the slower drive, in /usr/bin.

This likewise accounts for the split between /sbin and /usr/sbin, /lib and /usr/lib, etc.

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