ftp

File Transfer Protocol.

login

Sign on.

rlogin

Sign on to remote system.

rsh

Run shell or single command on remote system (not particularly secure).

ssh

Run shell or single command on remote system (secure).

talk

Exchange messages interactively with other terminals.

telnet

Connect to another system.

tftp

Trivial File Transfer Protocol.

uudecode

Decode file prepared for mailing by uuencode.

uuencode

Encode file containing binary characters for mailing.

vacation

Respond to mail automatically.

cmp

Compare two files, byte by byte.

comm

Compare items in two sorted files.

diff

Compare two files, line by line.

diff3

Compare three files.

cat

Concatenate files or display them.

chfn

Change user information for finger, email, etc.

cksum

Compute checksum.

chmod

Change access modes on files.

chsh

Change login shell.

cp

Copy files.

csplit

Split a file into pieces with a specific size or at specific locations.

dd

Copy files in raw disk form.

file

Determine a file's type.

head

Show the first few lines of a file.

less

Display files by screenful.

ln

Create filename aliases.

ls

List files or directories.

merge

Merge changes from different files.

mkdir

Create a directory.

more

Display files by screenful.

mv

Move or rename files or directories.

newgrp

Change current group.

pwd

Print working directory.

rcp

Copy files to remote system.

rm

Remove files.

rmdir

Remove directories.

split

Split files evenly.

tail

Show the last few lines of a file.

wc

Count lines, words, and characters.

cdda2wav

Rip a CD to create a computer-friendly WAV format.

cdparanoia

Rip a CD while providing extra features.

cdrdao

Copy a CD.

cdrecord

Record to a CD.

eject

Eject a removable disk or tape.

mpg321

Play an MP3 file.

volname

Provide the volume name of a CD-ROM.

lpq

Show status of print jobs.

lpr

Send to the printer.

lprm

Remove print job.

lpstat

Get printer status.

pr

Format and paginate for printing.

ar

Create and update library files.

as

Generate object file.

bison

Generate parsing tables.

cpp

Preprocess C code.

flex

Lexical analyzer.

g++

GNU C++ compiler.

gcc

GNU C compiler.

ld

Link editor.

m4

Macro processor.

make

Create programs.

ranlib

Regenerate archive symbol table.

rpcgen

Translate RPC to C code.

yacc

Generate parsing tables.

cvs

Manage different versions (revisions) of source files.

etags

Generate symbol list for use with the Emacs editor.

gdb

GNU debugger.

gprof

Display object file's profile data.

imake

Generate makefiles for use with make.

make

Maintain, update, and regenerate related programs and files.

nm

Display object file's symbol table.

patch

Apply patches to source code.

rcs

Manage different versions (revisions) of source files.

size

Print the size of an object file in bytes.

strace

Trace system calls and signals.

strip

Strip symbols from an object file.

apropos

Search manpages for topic.

egrep

Extended version of grep.

fgrep

Search files for literal words.

find

Search the system for files by name and take a range of possible actions.

grep

Search files for text patterns.

locate

Search a preexisting database to show where files are on the system.

strings

Search binary files for text patterns.

whereis

Find command.

echo

Repeat command-line arguments on the output.

expr

Perform arithmetic and comparisons.

printf

Format and print command-line arguments.

sleep

Pause during processing.

test

Test a condition.

bzip2

Compress files to free up space.

cpio

Create and unpack file archives.

gunzip

Expand compressed (.gz and .Z) files.

gzip

Compress files to free up space.

shar

Create shell archive.

tar

Copy files to or restore files from an archive medium.

zcat

Display contents of compressed files.

at

Execute commands later.

atq

Show jobs queued by at.

atrm

Remove job queued by at.

chgrp

Change file group.

chown

Change file owner.

crontab

Automate commands.

date

Display or set date.

df

Show free disk space.

du

Show disk usage.

env

Show environment variables.

finger

Display information about users.

kill

Terminate a running command.

printenv

Show environment variables.

ps

Show processes.

stty

Set or display terminal settings.

who

Show who is logged in.

col

Process control characters.

cut

Select columns for display.

emacs

Work environment with powerful text editing capabilities.

ex

Line editor underlying vi.

expand

Convert tabs to spaces.

fmt

Produce roughly uniform line lengths.

fold

Break lines.

gawk

Process lines or records one by one.

ghostscript

Display PostScript or PDF file.

groff

Format troff input.

ispell

Interactively check spelling.

join

Merge different columns into a database.

paste

Merge columns or switch order.

rev

Print lines in reverse.

sed

Noninteractive text editor.

sort

Sort or merge files.

tac

Print lines in reverse.

tr

Translate (redefine) characters.

uniq

Find repeated or unique lines in a file.

vi

Visual text editor.

xargs

Process many arguments in manageable portions.

banner

Make posters from words.

bc

Arbitrary precision calculator.

cal

Display calendar.

clear

Clear the screen.

man

Get information on a command.

nice

Reduce a job's priority.

nohup

Preserve a running job after logging out.

passwd

Set your login password.

script

Produce a transcript of your login session.

su

Become a superuser.

tee

Simultaneously store output in file and send to screen.

which

Print pathname of a command.