Useful Shell Shortcuts 26 comments

posted Saturday, May 26, 2007 by topfunky

A few weeks ago someone asked me to recommend a few useful books on Ruby. The first one? Using csh & tcsh. I spend a lot of time in the terminal and these shortcuts help in both tcsh and bash.

Reuse previous arguments

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

!! (Full contents of previous command)

How many times have you tried to edit a file, then realize that you need to be root to do it? Use bang-bang to quickly repeat the previous command, with other commands before or after.

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

!$ (Last arg of previous command)

Sometimes I need to reuse the last argument with another command, like here where I forgot to quote a string.

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

!^ (First argument of previous command)

I rarely use this, although it could have been used in the previous tip.

echo fish and chips
echo !^
=> 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.

echo fish and chips
=> fish and chips
echo !: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.

I like the tcsh behavior since you can hit TAB to see what you’re asking for. Using this in bash can be more adventurous since you don’t know what command will be run until you hit ENTER.

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

Sets

{a,b} (A set)

How often do 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 Apple-C or Apple-V.

./generate_random_password | pbcopy
pbpaste > file.txt
26 comments

Leave a response

  • sal

    great Post! i didn’t know about some of these…

    groovy man!

    cheers

  • Alpha Chen

    In bash, you can set up the magic space to show you what the ! commands will result in. To do this, add “Space: magic-space” to .inputrc.

    So with !pattern, when you do !rak and then hit space, it’ll be replaced with rake test:recent.

  • zoomiez

    I’ve been “getting around” to learning these for far too long. Thanks for the simple howto!

  • vince

    Fantastic! All of these were new for me.

  • davidyu

    I master these, thx

  • Jamie Hill

    Most helpful, thanks Geoff. Now we even have ways of keeping the terminal DRY ;)

  • James Hill

    Great post, so many helpful hints, and somewhat freaky that I’m posting so close to jamie hill.

  • Chris

    If you’re impressed by these somewhat basic tips, you are gonna love the zsh. Have a look at http://grml.org/zsh/ They have a great collection of zsh resources and tips.

  • atmos

    Nice one Geoffrey.

  • insa

    bash also have some nice shortcuts…

    insert last arg: alt + . (you can hold alt and press ”.” many times)

    search backward: alt + r and start typing command (more informative then !pattern)

    go to beginning/end of current string: ctrl+a, ctrl+e

    erase word: ctrl+w

    and many others…

  • Justin Dossey

    One of my favorites is !#—this command.

    So

    cp foo !#^.bak

    translates to

    cp foo foo.bak

    It’s great with very long file/pathnames.

  • Justin Dossey

    One more trick with that: !#$ is “whatever I just said.”

    echo abc def !#$.bak ghi jkl !#$.foo mno

    is the same as

    echo abc def def.bak ghi jkl jkl.foo mno

  • robc

    I’d be surprised if 

    wget '!$'

    worked very well.

    shell metacharacters don’t interpolate inside single quotes.

    One of my favourite uses of ”!!” is to test an expression before giving it to some destructive command. For example, check the list of files older than 120 days before deleting them:

    $ find . -mtime +365
... a bunch of files

    Oops, there’s one file I don’t want to delete:

    $ !! | grep -v my_very_important_file
find . -mtime +365 | grep -v my_very_important_file
... a bunch of files
    $ rm `!!`

  • topfunky

    @robc: !$ is intepolated inside single quotes in my shell, but double will work, too (the example I gave was an actual command that I used a few minutes before writing this article).

    Thanks to everyone for the other tips as well!

  • Mike Mondragon

    In the Beginning was the Command Line

  • Sandro

    Great post, It’s the first time I read about a ‘{}’ shell modifier :D

  • Klettergriffe

    Cool Post, thanks a lot for it.

    see you,

    peter :-)

  • Justin Turner

    Wow. Thanks a million.

  • Peter Burkholder

    “Insa” mentioned: search backward: alt + r and start typing command (more informative then !pattern)

    But in my experience it’s been Ctrl-r that searches backwards for patterns in your command history.

    Another favorite is the use of caret(^) substitution, which you can use to fix a typo in the previous command. E.g.

    $ some long command with a mizspelling in the middle of it
$ ^miz^mis

  • kortina

    great post. I’ll definitely use this stuff a lot, especially the {} trick.

    @insa: good call on the ctrl+e. I have always used ctrl+a, but for some reason never knew how to get to the end of the line.

  • Ruby on Rails examples

    I like the {}! Nice

  • joel

    for any of the recall commands, :p will print it and put it into the most recent slot in the history, rather than execute it. this is useful when you’re searching for that last “rm” command:

    dp 26% !rm:p rm /* dp 27%

    there’s no evidence that the command didn’t execute, so this would show that:

    dp 28% !ls:p ls / dp 29%

    ![n|string] is evaluates to all the arguments and options to the recalled command:

    dp 34% touch /tmp/t1 /tmp/t2

    dp 35% ls -l !* ls -l /tmp/t1 /tmp/t2 rw-r-r— 1 joel wheel 0 Jun 12 16:08 /tmp/t1 rw-r-r— 1 joel wheel 0 Jun 12 16:08 /tmp/t2

    dp 36% rm !t* rm /tmp/t1 /tmp/t2

    dp 37% ls !31* ls /tmp/t1 /tmp/t2 ls: /tmp/t1: No such file or directory ls: /tmp/t2: No such file or directory

  • Sam

    Never seen any of them before, they’re gunna save some precious time for me! Just what I need as i just switched to linux to linux as my main OS (wish it was a mac though (yes, I admit it, only for textmate (and yes, i do like my brackets))). Cheers me dears.

  • Dave

    Thanks for useful information. I really found Mac OS X specific very useful. The {} trick is cool

  • Ed

    Yes, the {} is nice.

    Thanks for cool post, Ed

  • Greg

    thanks for these, they’re totally awesome! Is there any concise way to use the output of a previous command as the input to a new one? i.e. I did:

    $ ls ~/Sites/grabbit/trunk/db/migrate/ | grep param

    and the output was a single file. Now I want to open that file with textmate. I want something like:

    $ mate [concise command]

    Does that exist?

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