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David Eisinger
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content/elsewhere/level-up-your-shell-game/index.md
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content/elsewhere/level-up-your-shell-game/index.md
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title: "Level Up Your Shell Game"
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date: 2013-10-24T00:00:00+00:00
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draft: false
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needs_review: true
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canonical_url: https://www.viget.com/articles/level-up-your-shell-game/
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---
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The Viget dev team was recently relaxing by the fireplace, sipping a
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fine cognac out of those fancy little glasses, when the conversation
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turned (as it often does) to the Unix command line. We have good systems
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in place for sharing Ruby techniques ([pull request code
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reviews](https://viget.com/extend/developer-ramp-up-with-pull-requests))
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and [Git tips](https://viget.com/extend/a-gaggle-of-git-tips), but
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everyone seemed to have a simple, useful command-line trick or two that
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the rest of the team had never encountered. Here are a few of our
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favorites:
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- [Keyboard
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Shortcuts](https://viget.com/extend/level-up-your-shell-game#keyboard-shortcuts)
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- [Aliases](https://viget.com/extend/level-up-your-shell-game#aliases)
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- [History
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Expansions](https://viget.com/extend/level-up-your-shell-game#history-expansions)
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- [Argument
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Expansion](https://viget.com/extend/level-up-your-shell-game#argument-expansion)
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- [Customizing
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`.inputrc`](https://viget.com/extend/level-up-your-shell-game#customizing-inputrc)
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- [Viewing Processes on a Given Port with
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`lsof`](https://viget.com/extend/level-up-your-shell-game#viewing-processes-on-a-given-port-with-lsof)
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- [SSH
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Configuration](https://viget.com/extend/level-up-your-shell-game#ssh-configuration)
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- [Invoking Remote Commands with
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SSH](https://viget.com/extend/level-up-your-shell-game#invoking-remote-commands-with-ssh)
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Ready to get your
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{.no-border
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align="top" height="24"
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style="display: inline; vertical-align: top; width: 24px !important; height: 24px !important;"}
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on? Good. Let's go.
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## Keyboard Shortcuts
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[**Mike:**](https://viget.com/about/team/mackerman) I recently
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discovered a few simple Unix keyboard shortcuts that save me some time:
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Shortcut Result
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---------------------- ----------------------------------------------------------------------------
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`ctrl + u` Deletes the portion of your command **before** the current cursor position
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`ctrl + w` Deletes the **word** preceding the current cursor position
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`ctrl + left arrow` Moves the cursor to the **left by one word**
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`ctrl + right arrow` Moves the cursor to the **right by one word**
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`ctrl + a` Moves the cursor to the **beginning** of your command
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`ctrl + e` Moves the cursor to the **end** of your command
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Thanks to [Lawson Kurtz](https://viget.com/about/team/lkurtz) for
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pointing out the beginning and end shortcuts
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## Aliases
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[**Eli:**](https://viget.com/about/team/efatsi) Sick of typing
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`bundle exec rake db:test:prepare` or other long, exhausting lines of
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terminal commands? Me too. Aliases can be a big help in alleviating the
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pain of typing common commands over and over again.
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They can be easily created in your `~/.bash_profile` file, and have the
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following syntax:
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alias gb="git branch"
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I've got a whole slew of git and rails related ones that are fairly
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straight-forward:
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alias ga="git add .; git add -u ."
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alias glo='git log --pretty=format:"%h%x09%an%x09%s"'
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alias gpro="git pull --rebase origin"
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...
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alias rs="rails server"
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And a few others I find useful:
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alias editcommit="git commit --amend -m"
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alias pro="cd ~/Desktop/Projects/"
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alias s.="subl ."
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alias psgrep="ps aux | grep"
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alias cov='/usr/bin/open -a "/Applications/Google Chrome.app" coverage/index.html'
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If you ever notice yourself typing these things out over and over, pop
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into your `.bash_profile` and whip up some of your own! If
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`~/.bash_profile` is hard for you to remember like it is for me, nothing
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an alias can't fix: `alias editbash="open ~/.bash_profile"`.
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**Note**: you'll need to open a new Terminal window for changes in
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`~/.bash_profile` to take place.
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## History Expansions
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[**Chris:**](https://viget.com/about/team/cjones) Here are some of my
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favorite tricks for working with your history.
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**`!!` - previous command**
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How many times have you run a command and then immediately re-run it
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with `sudo`? The answer is all the time. You could use the up arrow and
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then [Mike](https://viget.com/about/team/mackerman)'s `ctrl-a` shortcut
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to insert at the beginning of the line. But there's a better way: `!!`
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expands to the entire previous command. Observe:
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$ rm path/to/thing
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Permission denied
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$ sudo !!
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sudo rm path/to/thing
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**`!$` - last argument of the previous command**
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How many times have you run a command and then run a different command
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with the same argument? The answer is all the time. Don't retype it, use
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`!$`:
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$ mkdir path/to/thing
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$ cd !$
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cd path/to/thing
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**`!<string>` - most recent command starting with**
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Here's a quick shortcut for running the most recent command that *starts
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with* the provided string:
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$ rake db:migrate:reset db:seed
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$ rails s
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$ !rake # re-runs that first command
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**`!<number>` - numbered command**
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All of your commands are stored in `~/.bash_history`, which you can view
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with the `history` command. Each entry has a number, and you can use
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`!<number>` to run that specific command. Try it with `grep` to filter
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for specific commands:
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$ history | grep heroku
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492 heroku run rake search:reindex -r production
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495 heroku maintenance:off -r production
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496 heroku run rails c -r production
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$ !495
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This technique is perfect for an alias:
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$ alias h?="history | grep"
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$ h? heroku
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492 heroku run rake search:reindex -r production
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495 heroku maintenance:off -r production
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496 heroku run rails c -r production
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$ !495
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Sweet.
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## Argument Expansion
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[**Ryan:**](https://viget.com/about/team/rfoster) For commands that take
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multiple, similar arguments, you can use `{old,new}` to expand one
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argument into two or more. For example:
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mv app/models/foo.rb app/models/foobar.rb
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can be
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mv app/models/{foo,foobar}.rb
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or even
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mv app/models/foo{,bar}.rb
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## Customizing .inputrc {#customizing-inputrc}
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[**Brian:**](https://viget.com/about/team/blandau) One of the things I
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have found to be a big time saver when using my terminal is configuring
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keyboard shortcuts. Luckily if you're still using bash (which I am), you
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can configure shortcuts and use them in a number of other REPLs that all
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use readline. You can [configure readline keyboard shortcuts by editing
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your `~/.inputrc`
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file](http://cnswww.cns.cwru.edu/php/chet/readline/readline.html#SEC9).
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Each line in the file defines a shortcut. It's made up of two parts, the
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key sequence, and the command or macro. Here are three of my favorites:
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1. `"\ep": history-search-backward`: This will map to escape-p and will
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allow you to search for completions to the current line from your
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history. For instance, it will allow you to type "`git`" into your
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shell and then hit escape-p to cycle through all the git commands
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you have used recently looking for the correct completion.
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2. `"\t": menu-complete`: I always hated that when I tried to tab
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complete something and then I'd get a giant list of possible
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completions. By adding this line you can instead use tab to cycle
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through all the possible completions stopping on which ever one is
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the correct one.
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3. `"\C-d": kill-whole-line`: There's a built-in key command for
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killing a line after the cursor (control-k), but no way to kill the
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whole line. This solves that. After adding this to your `.inputrc`
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just type control-d from anywhere on the line and the whole line is
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gone and you're ready to start fresh.
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Don't like what I mapped these commands to? Feel free to use different
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keyboard shortcuts by changing that first part in quotes. There's a lot
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more you can do, just check out [all the commands you can
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assign](http://cnswww.cns.cwru.edu/php/chet/readline/readline.html#SEC13)
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or create your own macros.
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## Viewing Processes on a Given Port with lsof
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[**Zachary:**](https://viget.com/about/team/zporter) When working on
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projects, I occassionally need to run the application on port 80. While
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I could use a tool like [Pow](http://pow.cx/) to accomplish this, I
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choose to use [Passenger
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Standalone](http://www.modrails.com/documentation/Users%20guide%20Standalone.html).
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However, when trying to start Passenger on port 80, I will get a
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response that looks something like "The address 0.0.0.0:80 is already in
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use by another process". To easily view all processes communicating over
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port 80, I use [`lsof`](http://linux.die.net/man/8/lsof) like so:
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sudo lsof -i :80
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From here, I can pin-point who the culprit is and kill it.
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## SSH Configuration
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[**Patrick:**](https://viget.com/about/team/preagan) SSH is a simple
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tool to use when you need shell access to a remote server. Everyone is
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familiar with the most basic usage:
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$ ssh production.host
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Command-line options give you control over more options such as the user
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and private key file that you use to authenticate:
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$ ssh -l www-data -i /Users/preagan/.ssh/viget production.host
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However, managing these options with the command-line is tedious if you
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use different private keys for work-related and personal servers. This
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is where your local `.ssh/config` file can help -- by specifying the
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host that you connect to, you can set specific options for that
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connection:
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# ~/.ssh/config
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Host production.host
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User www-data
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IdentityFile /Users/preagan/.ssh/viget
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Now, simply running `ssh production.host` will use the correct username
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and private key when authenticating. Additionally, services that use SSH
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as the underlying transport mechanism will honor these settings -- you
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can use this with Github to send an alternate private key just as
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easily:
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Host github.com
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IdentityFile /Users/preagan/.ssh/github
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**Bonus Tip**
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This isn't limited to just setting host-specific options, you can also
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use this configuration file to create quick aliases for hosts that
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aren't addressable by DNS:
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Host prod
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Hostname 192.168.1.1
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Port 6000
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User www-data
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IdentityFile /Users/preagan/.ssh/production-key
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All you need to do is run `ssh prod` and you're good to go. For more
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information on what settings are available, check out the manual
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([`man ssh_config`](http://linux.die.net/man/5/ssh_config)).
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## Invoking Remote Commands with SSH
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[**David**:](https://viget.com/about/team/deisinger) You're already
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using SSH to launch interactive sessions on your remote servers, but DID
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YOU KNOW you can also pass the commands you want to run to the `ssh`
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program and use the output just like you would a local operation? For
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example, if you want to pull down a production database dump, you could:
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1. `ssh` into your production server
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2. Run `mysqldump` to generate the data dump
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3. Run `gzip` to create a compressed file
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4. Log out
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5. Use `scp` to grab the file off the remote server
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Or! You could use this here one-liner:
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ssh user@host.com "mysqldump -u db_user -h db_host -pdb_password db_name | gzip" > production.sql.gz
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Rather than starting an interactive shell, you're logging in, running
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the `mysqldump` command, piping the result into `gzip`, and then taking
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the result and writing it to a local file. From there, you could chain
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on decompressing the file, importing it into your local database, etc.
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**Bonus tip:** store long commands like this in
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[boom](https://github.com/holman/boom) for easy recall.
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------------------------------------------------------------------------
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Well, that's all we've got for you. Hope you picked up something useful
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along the way. What are your go-to command line tricks? Let us know in
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the comments.
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