I-L

ICMP (Internet Control Message Protocol)

A protocol for sending online error control messages. Associated with the ping command.

ifconfig

The ifconfig command is used to configure and display network devices.

init

The init process is the first Linux process called by the kernel. This process starts other processes that compose a working Linux system, including the shell.

Initial RAM Disk

RHEL uses an initial RAM disk in the boot process; it's stored as an initrd-`uname -r`.img file in the /boot directory. You can create your own from the currently booted kernel with the mkinitrd initrd-`uname -r`.img `uname -r` command.

Internet Print Protocol (IPP)

The Internet Print Protocol (IPP) is the evolving standard for printers shared over networks. It's being adapted by all major operating systems; the Linux implementation is CUPS.

IP forwarding

IP forwarding is when data is forwarded between computers or networks through your computer.

iptables

The iptables command is the basic command for firewalls and masquerading.

IPv4, IPv6

IPv4 and IPv6 are different systems of IP addressing. Version 4 is what we use today and is based on 32-bit addresses; version 6 is coming on line and is based on 128-bit addresses.

iSCSI (Internet SCSI)

Internet SCSI is a network protocol standard, associated with SCSI-3 specifications on network storage devices.

KDE

A GUI for Linux and Unix computers. Also known as the K Desktop Environment.

Kdump

The Kdump service allows you to configure what happens in the event of a kernel crash. You can dedicate a specific amount of RAM to the process, which is then unavailable for other processes.

kernel

The kernel is the heart of any operating system. It loads device drivers. You can recompile a Linux kernel for additional drivers, for faster loading and to minimize the required memory.

kernel module

Kernel modules are pluggable drivers that can be loaded and unloaded into the kernel as needed. Some loaded kernel modules are shown with the lsmod command.

Kickstart

Kickstart is the Red Hat automated installation system that allows you to supply the answers required during the installation process. When properly configured, a kickstart floppy can allow you to start your computer and install RHEL automatically from a network source.

LDP (Linux Documentation Project)

The LDP is a global effort to produce reliable documentation for all aspects of the Linux operating system. Its work is available online at www.tldp.org.

lftp

The lftp command starts a slightly more flexible FTP command line client.

Lightweight Directory Access Protocol (LDAP)

The Lightweight Directory Access Protocol allows you to keep authentication information on a central server on your network.

locate

The locate command searches through a default database of files and directories. The database is refreshed daily with the mlocate.cron script in the /etc/ cron.daily/ directory.

logrotate

The logrotate command utility allows you to maintain log files. By default, RHEL uses the cron daemon to rotate, compress, and remove various log files.

lpc

You can use the lpc command to scan all configured print devices and queues.

lpq

You can use the lpq command to view print jobs still in progress.

lpr

You can use the lpr command to send print requests.

lprm

You can use the lprm command to remove print jobs from the queue.

logical extent (LE)

A logical extent (LE) chunk of disk space that corresponds to a physical extent (PE).

logical volume (LV)

A logical volume (LV) is composed of a group of logical extents (LEs).

Logical Volume Management (LVM)

Logical Volume Management (LVM) allows you to set up a filesystem on multiple partitions. Also known as the Logical Volume Manager.

lsattr

The lsattr command lists file attributes.

lvcreate

The lvcreate command creates a logical volume (LV) from a specified number of available physical extents (PEs).

lvdisplay

The lvdisplay command specifies current configuration information for logical volumes (LVs).

lvextend

The lvextend command allows you to increase the physical volume (PV) area allocated to a logical volume (LV).

lvremove

Functionally opposite to the lvcreate command.