Bash Commands

Resources

• http://www.ibm.com/developerworks/aix/library/au-unixtext/index.html
• http://ss64.com/bash/

Quizzes

• Folder hierarchy concepts (ls, cd, .., ~, /)
• Basic text manipulation
• File manipulation
• Output direction (>, < |)
• Utils
• More Text manipulation (sort, uniq, nl)
• Processes
• Remote
• Sed
• Grep
• Awk
• rsync
• Scripting

Filename aliasing

• * match 0 or more characters
• ? match any single character
• [abc...] match any enclosed character, hyphen to specify range
• [!abc...] not any character
• ~ home directory of current user
• (a|b) pattern a or b
• f{oo,u}bar generates foobar or fubar
  • echo {1...10} will list numbers 1 through 10
• quoting
  • ": $, ' ", \
  • ': only '

Command Forms

• cmd & - execute in background
• cmd1 ; cmd2 - execute multiple commands
• {cmd1; cmd2;} execute commands as a group in the current shell
• (cmd2; cmd2) execute commands as a group in a subshell (I don't know what this means)
• cmd1 | cmd2 pipe output from cmd2 as intput to cmd 2
• cmd1 `cmd2` use cmd2 output as arguments to cmd1
• cmd > file send output to file and overwrite
• cmd &> file send output and errors to file and overwrite
• cmd >> file send output to file and append
• cmd < file take input for cmd from file
• (date; ls) > file - All output is sent to the file
• cmd | tee files send to standard out and files

Command History

• !! previous command
• !n command n
• !-n command n ago
• !string most recent command that starts with stirng
• !?string[?] most recent command that contains string

Terminal Commands

• cd
• pwd

Special Operations

• <
• >
• |
• >>
• tee
• .
• !!
• -
• ~, /
• ..

Control Characters (all are ctrl+)

• A: beginning of line
• C: terminate foreground job
• E: end of line
• R: Backward search in history for text in command
• W: Erase backwards to whitespace
• Z: Pauses foreground job
• L: clear the screen
• U: clears everything from the cursor to the beginning of the line
• K: clears everything from the cursor to the end of the line
• T: swap the last two characters before the cursor
• B: move the cursor backward one character
• F: forward one character
• J or M: enter
• N: Next in history (down arrow)
• P: Previous in history (up arrow)
• O: Enter the current command and put in back on the command line for further editing
• Y: Paste from ^W, ^K or ^U like commands

Text Processing

• tr [options] set1 [set2]
  • alnul, alpha, blank, digit, space, upper
  • lower to upper "tr a-z A-Z"
  • -d: delete, -s:squeeze(repeats the operation until no changes occur), -cs
• uniq
  • unique a file by line
  • -c: print the number of times each line occurred
  • -i: ignore case
  • -d: print only duplicated lines
  • -u: print only unique lines
  • -w N: check only N characters
• sort
  • -b: ignore leading blanks
  • -f: ignore case
  • -r: Reverse
  • -u: unique
• wc
  • Shows the line, word and character count
  • -c: print only the byte count
  • -w: print only the word count
  • -l: print only the newline count
  • Example: grep FIXME *.c | wc -l count all the instance of FIXME in *.c files in the current directory
• fold
  • Wraps lines at a given width, by default, 80
  • -s: break at word boundaries, last blank before the maximum.
  • -w WIDTH: sets width
• nl
  • -b STYLE
    • a: number all lines
    • t: number only nonempty lines
    • n:do not number lines
    • pREGEXP: number only lines that contain a match for REGEXP
• diff

Other

• ls
• less
• cat, tac
• man
• head
• tail
• bc
• rev
• echo
  • -n: Do not print the trailing newline
• mapfile

Power Tools

• sed
• grep
• rsync

Files and Folders

• mv
• rm
• mkdir
• cp
• rmdir
• chmod
• ln

Utils

• cal
• date
• find
• gzip
• tar
• time

Remote

• ssh
• screen
• ftp
• ping
• rcp
• scp
• wget

Processes

• bg
• fg
• jobs
• kill
• ps
• coproc

Scripting

• if
• wait
• case