Common Unix Commands

Most commonly used UNIX Commands:

Terminal control characters for C-shell

• ^h or backspace - erase previously typed character
• ^u - erase entire line of input so far typed
• ^d - end-of-input for programs reading from terminal
• ^s - stop printing on terminal
• ^q - continue printing on 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

Authentication

• login - access computer; start interactive session
• logout - disconnect terminal session
• exit - disconnect terminal session
• passwd - change local login password; you must set a strong password that is not easily guessed

Information Commands

• 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
• finger - find out info about a user@system
• whois - look up information in the Stanford Directory
• env – information about the current session
• uname – print name of current system

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

Directory Management

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

File Processing

• 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
• grep - display lines that match a pattern
• 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

Space/Disk Usage

• df - summarize free space on disk drive
• du - show disk space used by files or directories

Special characters

• * - 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 - print process screen
• 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 (in .login)
• sh, csh - execute command file
• sleep - delay for a specified amount of time
• wait - Wait for the specified process

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

Interpreted languages and data manipulation utilities

• sed -stream editor
  
• 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

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
• ftp - network file transfer program – plain text passwords
• rlogin - remote login to “trusted” computer that is not kerberized
• rsh - execute single command on remote “trusted” computer
• rcp - remote file copy to/from “trusted” computer
• host - find IP address for given host name, or vice versa
• 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 - Compaq(HP) Fortran 77 compiler
• f95 - Compaq(HP) Fortran 90/95 compiler
• f2c - convert fortran source code to C source code
• cc, c89 – Compaq(HP) ANSI 89 standard C compiler
• cxx - Compaq(HP) C++ compiler
• gcc - GNU C compiler
• g++ - GNU C++ compiler
• pc - Compaq(HP) Pascal compiler
• dbx - command-line symbolic debugger for compiled C or Fortran
• ladebug – X Window symbolic debugger for compiled C or Fortran
• make - recompile programs from modified source
• gmake - GNU version of make utility
• cflow - generate C flow graph
• error - analyze and disperse compiler error messages

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