General

* at
o Runs a command or script at a given time
* atq
o Shows the jobs that are scheduled to run
* atrm
o Used to remove a job that is scheduled to run
* batch
o 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
o Displays the contents of a file to the screen
* cd
o Changes to another directory
* chgrp
o Changes the group associated with one or more files to a different group
* chmod
o Controls file security
* chown
o Changes file ownership
* chsh
o Sets your login shell
* cmp
o Used to compare two files
* cp
o Copies a file to another directory (and you can rename the file at the same time)

* df
o Shows a report of how the disk space is used
* dump
o Backs up files
* edquota
o Used to edit disk quotas associated with user accounts
* fdisk
o Formats and partitions a disk
* file
o Displays the file type
* find
o Used to find specific files
* fsck
o Performs a verification of the file system
* grep
o Searches for a particular string of characters in a file
* groupadd
o Creates a new group
* groupdel
o Deletes an existing group
* groupmod
o Modifies an existing group
* info
o Displays information and documentation about a command or a utility
* kbconfig
o Used to configure a keyboard
* kbdrate
o Sets the repeat rate for the keyboard
* kill
o Stops a process
* less
o Shows the contents of a file, with the ability to go back or more ahead in the file
* ln
o Creates symbolic file links
* lpd
o Configures a printer
* lpq
o Used to check a print queue
* lpr
o Prints a file
* lprm
o Removes print jobs from the queue
* ls
o Lists the contents of a directory
* man
o Displays documentation in Linux
* mkdir
o Creates a directory
* more
o Displays text in a file one screen at a time
* mount
o Lists the disks currently mounted; also mounts file systems and devices
* mv
o Moves a file to a different directory
* newfs
o Creates a new file system
* passwd
o Used to change a password
* pr
o Used to format a file into pages or columns for printing
* printenv
o Prints environment variables that are already set up

* ps
o Shows currently running processes
* pwck
o Checks the /etc/ passwd and /etc/shadow files to make sure password authentication entries are valid
* pwd
o Shows the directory you are in
* quota
o Displays the disk quota for users
* quotacheck
o Verifies the disk quota files, including reporting disk usage
* quotaon/quotaoff
o Enables or disables disk quotas
* repquota
o Makes a report of disk quotas
* restore
o Restores files (from a dump)
* rm
o Removes a file or directory
* rmdir
o Deletes a directory that is empty
* sort
o Sorts the contents of a text file
* swapon/swapoff
o Turns page file devices on or off
* sync
o Forces information in memory to be written to disk
* tar
o Used to archive files
* top
o Shows a report of the main, current processes engaging the central processing unit (CPU)
* touch
o Creates an empty file
* umount
o Dismounts a file system
* uname
o Shows information about the operating system
* useradd
o Configures a new user account
* userdel
o Removes an existing user account
* usermod
o Modifies an existing user account
* vmstat
o Displays a report about virtual memory use
* whereis
o Used to locate information about a specific file, such as a program

Network Commands

* finger
o Provides information about a user
* ftp
o Enables file transfers
* ifconfig
o Used to set up a network interface
* ipchains
o Used to manage a firewall
* netstat
o Shows network connection information
* nfsstat
o Shows statistics for Network File System (NFS) file upload and download activity
* nslookup
o Used to query information on Internet Domain Name System (DNS) servers
* ping
o Used to poll a TCP/IP node to verify you can communicate with it
* route
o Displays routing table information and can be used to configure routing
* showmount
o Shows clients that have mounted volumes on a NFS server
* who
o Shows who is logged on
* wvdial
o Controls a Point-to-Point Protocol (PPP)-based modem dialer