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Common unix commands and utilities



Copyright Phillip Farrell. Last revision August 6, 2010

This page was created to list commonly used Unix commands and useful utilities that were available on a time-sharing Tru64 Unix system operated by the School of Earth Sciences in the early 2000s.

This page was edited in 2010 to remove special programs that were only available on the School's system, which is no longer in use. The remaining commands and utilities listed here should be available for all varieties of Unix and Linux, including Mac OS X (from the Terminal application).

Program listings are organized by general subject categories. Keys preceded by a ^ character are CONTROL key combinations. Access the online manual with the man program to get more information on these programs, for example,
      man cp

To find a program not on this list (and there are hundreds), try the man program with the -k option followed by a keyword, for example,
      man -k tape
to find all on-line manual entries that refer to programs that work with tapes.

Terminal control characters for C-shell (csh)

^h, backspace erase previously typed character
^u erase entire line of input so far typed
^d end-of-input for programs reading from terminal
^s suspend writing to terminal (freezes terminal)
^q continue writing to terminal
^z suspend currently running job; restart with bg or fg
^c kill currently running program and allow clean-up before exiting
^\ emergency kill of currently running program with no chance of cleanup

Also see a list of special characters that should not be used in filenames.

Login and authentication

login access computer; start interactive session
logout disconnect terminal session
passwd change local login password; you must set a strong password that is not easily guessed
kinit obtain kerberos ticket for connections to other kerberized computers
kdestroy destroy kerberos tickets (authorizations)

Information

date show date and time
history list of previously executed commands
man show online documentation by program name
info online documentation for GNU programs
w, who who is on the system and what they are doing
whoami who is logged onto this terminal
top show system stats and top CPU using processes
uptime show one line summary of system status

File management

cat combine files
cp copy files
ls list files in a directory and their attributes
mv change file name or directory location
rm remove files
ln create another link (name) to a file
chmod set file permissions
crypt encode/decode a file with a private key
gzip, gunzip compress/decompress a file
find find files that match specific criteria

Display contents of files

cat copy files to display device
more show text file on display terminal with paging control
head show first few lines of a file(s)
tail show last few lines of a file; or reverse line order
vi full-featured screen editor for modifying text files
pico simple screen editor for modifying text files
grep display lines that match a pattern
lpr send file to printer
pr format file with page headers, multiple columns, etc.
diff compare two files and show differences
cmp compare two binary files and report if different
comm compare two files; show common or unique lines
od display binary files as eqivalent octal/hex codes
strings show printable text embedded in binary files
file examine file(s) and guess type: text, data, program, etc.
wc count characters, words, and lines in a file

Directories

cd change to new directory
mkdir create new directory
rmdir remove empty directory (you must remove files first)
mv change name of directory
pwd show current directory

Disks

df summarize free space on disk filesystems
du show disk space used by files or directories

Special character handling for C-shell (See man csh)

* match any characters in a file name
~user shorthand for home directory of user
$name substitute value of variable name
\ turn off special meaning of character that follows
' in pairs, quote string with special chars, except !
" in pairs, quote string with special chars, except !, $
` in pairs, substitute output from enclosed command

Controlling program execution for C-shell (See man csh)

& run job in background
^c kill job in foreground
^z suspend job in foreground
fg restart suspended job in foreground
bg run suspended job in background
; delimit commands on same line
() group commands on same line
! re-run earlier commands from history list
jobs list current jobs
ps show process information
kill kill background job or previous process
nice run program at lower priority
at run program at a later time
crontab run program at specified intervals
limit see or set resource limits for programs
alias create alias name for program (normally used in .login file)
sh, csh execute command file

Controlling program input/output for C-shell (See man csh)

| pipe output to input
> redirect output to a storage file
< redirect input from a storage file
>> append redirected output to a storage file
tee copy input to both file and next program in pipe
script make file record of all terminal activity

Email and communication

msgs read system bulletin board messages
mailx send/read email; can be run by other programs to send exisiting files via email
uuencode
uudecode
encode/decode a binary file for transmission via email
rn read USENET news groups

Editors and formatting utilities

sed programmable text editor for data streams
vi full-featured editor for character terminals
emacs GNU emacs editor for character terminals
xemacs GNU emacs editor for X Window terminals
pico very simple text editor
fmt fill and break lines to make all same length
fold break long lines to specified length

X Window client programs (output to X terminal or server)

xterm provide login shell window
xauth manipulate authorization files
xload show system load
xman full screen online manual viewer
xemacs GNU emacs editor
gv interface to contol gs to display PostScript or PDF files on screen
xdvi display DVI files on X Window (screen preview)
gnuplot interactive data plotting on screen

TeX typesetting system

tex process TeX files to DVI (device independent) output
latex process LaTeX files to DVI
dvips print DVI files on Postscript laser printer
xdvi display DVI files on X Window (screen preview)
latex2html translate LaTeX files to HTML (for web pages)

Printing (BSD based)

lpr send file to print queue
lpq examine status of files in print queue
lprm remove a file from print queue
enscript convert text files to PostScript format for printing

Interpreted languages and data manipulation utilities

sed programmable text editor for data streams
awk pattern scanning and processing language
perl Practical Extraction and Report Language
sort sort or merge lines in a file(s) by specified fields
tr translate characters
cut cut out columns from a file
paste paste columns into a file
dd copy data between devices; reblock; convert EBCDIC

Graphics and mapping

gnuplot interactive data plotting; outputs to PostScript or X Window
gs "ghostscript" converter displays PostScript files on X Window displays or other devices

Networking/communications

ssh remote login/command execution; encrypted
scp remote non-interactive file copy; encrypted
sftp remote interactive file copy; encrypted
telnet remote network login; plain text password - not recommended
ftp network file transfer program; plain text password - not recommended
host find IP address for given host name, or vice versa
lynx web browser for character based (text-only) terminals
gzip, gunzip compress/decompress a file
tar combine multiple files/dirs into single archive
uuencode
uudecode
encode/decode a binary file for transmission via email

Compilers, interpreters and programming tools

csh command language interpreter (C-shell scripts)
ksh command language interpreter (Korn-shell scripts)
sh command language interpreter (Borne-shell scripts)
f77 Fortran 77 compiler
f2c convert fortran source code to C source code
gcc GNU C compiler
g++ GNU C++ compiler
dbx command-line symbolic debugger for compiled C or Fortran
make recompile programs from modified source
cflow generate C flow graph

Programming libraries (see man library_name)

lapack Fortran 77 routines for numerical linear algebra (supersedes LINPACK and EISPACK)
X routines to interface with X window system (no man page -- get the X Toolkit book)
dbm database routines
xdr library routines for external data representation
netcdf routines for machine independent data representation

Tape manipulation and archiving

mt manipulate tape drive and position tape
dd unformatted tape read and write; file conversion
tar archive disk files on tape or disk
ltf read/write ANSI standard label tapes

Comments or Questions?