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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