How-To: Bash
Documentation & References
Command Line Editing Cheat Sheet
- CTRL + c : Kill the foreground process.
- CTRL + z : Suspend the foreground process.
- CTRL + d : Exit the shell.
- CTRL + l : Clears the screen.
- CTRL + e : Go to the end of the line.
- CTRL + a : Go to the beginning of the line.
- CTRL + h : Backspace.
- CTRL + u : Clears the line before the cursor position.
- CTRL + k : Delete everything after the cursor, adding the killed text to the delete buffer.
- CTRL + w : Delete the word before the cursor, adding the killed text to the delete buffer.
- CTRL + y : Pastes the contents of the delete buffer.
- CTRL + _ : Undoes the last edit.
- ESC + l : Convert the word to lowercase letters.
- ESC + l : Convert the word to uppercase letters.
- ESC + f : Move forward a word.
- ESC + b : Move backward one word.
- ESC + 2 then ESC + b : Move back 2 words.
- CTRL + r : Interactively search backwards through the command history (repeat to search again).
- CTRL + s : Interactively search forward through the command history (repeat to search again).
- CTRL + g : Abort the interactive search and restore the command line.
- !! : Repeat the last command.
- !-2 : Repeat the previous to last command.
- !5 : Repeat command from history line 5 (run history to see the history).
- !echo : Repeat the last command that started with echo.
- !?date? : Repeat the last command that contains (not necessarily starts with) date.
- !:3 : Replaces with the third argument from the last command.
- !:1-2 : Replaces with the first through second arguments from the last command.
- !:^ : Replaces with the first argument from the last command.
- !:$ : Replaces with the last argument from the last command.
- !:$:h : Replaces with the last argument from the last command, removing the trailing pathname component.
- !:$:r : Replaces with the last argument from the last command, removing the trailing suffix/extension.
- !:$:e : Replaces with the last argument from the last command, removing all but the suffix/extension.
- !:* : Replaces with all arguments from the last command.
- ^old^new^ : Repeat the last command substituting old with new.
- !:s/old/new/ : Repeat the last command substituting old with new (add g to the end to replace all occurrences).
- ((x=y*5)) : Sets the variable x to the value of the variable y times 5.
Tips & Tricks
Disabling saving of the command history
This will disable saving the command history when you exit Bash:
Clearing the command history
This will clear the command history:
Iterating over a sequence of numbers
To iterate a loop across a series of numbers use 'seq'. The following will display 'line# X' with X starting at 4 and ending at 12 with a step size of 2. The step size is optional, with a default value of 1. The ending value is also optional, when it is omitted the single value denotes the ending value with an implicit starting value of 1.
for i in $(seq 4 2 12)
do
echo "line# $i"
done
Extended pattern matching with 'extglob'
If the extglob shell option is enabled using the shopt builtin (with
shopt -s extglob), several extended pattern matching operators are recognized. In the following description, a pattern-list is a list of one or more patterns separated by a |. Composite patterns may be formed using one or more of the following sub-patterns:
?(pattern-list)
Matches zero or one occurrence of the given patterns
Matches zero or more occurrences of the given patterns
Matches one or more occurrences of the given patterns
Matches one of the given patterns
Matches anything except one of the given patterns
The following example will list all files ending in avi or mkv:
In the following example only files that do not end in avi or mkv will be listed:
ShellCheck: Shell script analysis tool
ShellCheck is a lint style tool that catches common shell scripting mistakes.
