Part 2: Helpful Command-Line Commands (Linux)

By Kyle Reasons
Contributing Writer, RealTechNews

General

• at

• Runs a command or script at a given time

atq

• Shows the jobs that are scheduled to run

atrm

• Used to remove a job that is scheduled to run

batch

• Runs a command or script and is really a subset of the at command that takes you to the at>prompt if you type only batch

cat

• Displays the contents of a file to the screen

cd

• Changes to another directory

chgrp

• Changes the group associated with one or more files to a different group

chmod

• Controls file security

chown

• Changes file ownership

chsh

• Sets your login shell

cmp

• Used to compare two files

cp

• Copies a file to another directory (and you can rename the file at the same time)

• df

• Shows a report of how the disk space is used

dump

• Backs up files

edquota

• Used to edit disk quotas associated with user accounts

fdisk

• Formats and partitions a disk

file

• Displays the file type

find

• Used to find specific files

fsck

• Performs a verification of the file system

grep

• Searches for a particular string of characters in a file

groupadd

• Creates a new group

groupdel

• Deletes an existing group

groupmod

• Modifies an existing group

info

• Displays information and documentation about a command or a utility

kbconfig

• Used to configure a keyboard

kbdrate

• Sets the repeat rate for the keyboard

kill

• Stops a process

less

• Shows the contents of a file, with the ability to go back or more ahead in the file

ln

• Creates symbolic file links

lpd

• Configures a printer

lpq

• Used to check a print queue

lpr

• Prints a file

lprm

• Removes print jobs from the queue

ls

• Lists the contents of a directory

man

• Displays documentation in Linux

mkdir

• Creates a directory

more

• Displays text in a file one screen at a time

mount

• Lists the disks currently mounted; also mounts file systems and devices

mv

• Moves a file to a different directory

newfs

• Creates a new file system

passwd

• Used to change a password

pr

• Used to format a file into pages or columns for printing

printenv

• Prints environment variables that are already set up

ps

• Shows currently running processes

pwck

• Checks the /etc/ passwd and /etc/shadow files to make sure password authentication entries are valid

pwd

• Shows the directory you are in

quota

• Displays the disk quota for users

quotacheck

• Verifies the disk quota files, including reporting disk usage

quotaon/quotaoff

• Enables or disables disk quotas

repquota

• Makes a report of disk quotas

restore

• Restores files (from a dump)

rm

• Removes a file or directory

rmdir

• Deletes a directory that is empty

sort

• Sorts the contents of a text file

swapon/swapoff

• Turns page file devices on or off

sync

• Forces information in memory to be written to disk

tar

• Used to archive files

top

• Shows a report of the main, current processes engaging the central processing unit (CPU)

touch

• Creates an empty file

umount

• Dismounts a file system

uname

• Shows information about the operating system

useradd

• Configures a new user account

userdel

• Removes an existing user account

usermod

• Modifies an existing user account

vmstat

• Displays a report about virtual memory use

whereis

• Used to locate information about a specific file, such as a program

Network Commands

• finger

• Provides information about a user

ftp

• Enables file transfers

ifconfig

• Used to set up a network interface

ipchains

• Used to manage a firewall

netstat

• Shows network connection information

nfsstat

• Shows statistics for Network File System (NFS) file upload and download activity

nslookup

• Used to query information on Internet Domain Name System (DNS) servers

ping

• Used to poll a TCP/IP node to verify you can communicate with it

route

• Displays routing table information and can be used to configure routing

showmount

• Shows clients that have mounted volumes on a NFS server

who

• Shows who is logged on

wvdial

• Controls a Point-to-Point Protocol (PPP)-based modem dialer