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.
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.