useful shell command history shortcuts

Reuse previous arguments

The ! operator gives you a quick way to refer to parts of the previous command.

!! (Full contents of previous command)

 emacs /etc/init.d/mongrel_cluster
=> Permission Denied
 sudo !!
=> Now opens the file as root

!$ (Last arg of previous command)

 wget http://weather.yahooapis.com/forecastrss?p=98117
=> wget: No Match
 wget '!$'
=> Now it works

!^ (First argument of previous command)

 echo fish and chips
 cho !^
=> fish # First argument

!:1 (Argument by number)

!:1 is the same as !^. The difference is that you can reference any element of the previous command.

 cho fish and chips
=> fish and chips
 cho !:1
=> fish # Same thing as !^

 echo fish and chips
 echo !:2
=> and # Word 2 in previous command, zero-indexed

 echo fish and chips
 echo !:0
=> echo # The very first word in the previous command

 echo fish and chips
 echo !:1-3
=> fish and chips # A range

!pattern (Repeat last command in history with pattern)

The bang is useful for re-running a command that you’ve run before. Spell out the first few letters and hit ENTER (or TAB to show the completion in tcsh). The shell will search backwards in your history until it finds a command that starts with the same letters.

 rake test:recent
...

 !rak
=> Runs 'rake test:recent' or last command starting with 'rak'

Sets:
{a,b} (A set)

How often to you rename just part of a file? The {} syntax is convenient.

 mv file.{txt,xml}
=> Expands to 'mv file.txt file.xml'

 mv file{,.orig}
=> Expands to 'mv file file.orig'

 mkdir foo{1,2,3}
=> Expands to 'mkdir foo1 foo2 foo3'

Mac OS X-specific

 pbcopy and pbpaste

In Mac OS X, you can copy things to the clipboard and read them back out. This is nice because you can reuse it in the shell or back in the OS with command-C or command-V.

 ./generate_random_password | pbcopy

 pbpaste > file.txt