Bash Tips and Tricks for Ninja...

bash tricks

## Copy (OSX only)

Pipe anything to `pbcopy` to copy it to the clipboard: `cat ~/.ssh/id_rsa.pub | pbcopy`

## The last argument

To insert the last argument of the previous command wherever the cursor currently is, press `alt+.` (or, on a mac, `esc+.`)

## File expansions

`touch {a,b,c}.txt` - writes `a.txt`, `b.txt`, `c.txt`

`rm [ab].txt` - deletes `a.txt` and `b.txt`

## End of Line, Flynn

You can use `Ctrl+a` and `Ctrl+e` to move the cursor to the start and end of the line respectively

## cd

The cd command has a history stack. `cd -` will take you to the previous directory you were in (running it again will take you back). `cd -3` will take you three directories back. (so, `cd -` is the same as `cd -1`)

You can use the `dirs -v` command to see the current stack. The ten most recent ones can be shown in oh-my-zsh with the `d` command.

## Misspellet Commands

`lk -al` - throws an error - lk: command not found
`^lk^ls` - re-runs the previous command, replacing `lk` with `ls`

## BANG!

Bang arguments can be appended with `:p` to preview the command before executing it (oh-my-zsh enables this all the time automatically)

### Bang Bang

The one that everyone has hopefully heard of is `!!` - repeat the last command. Most commonly used:

    rm -rf /
    This operation requires root
    sudo !!

### Bang Number

`!3` will run the 3rd command in your bash history
`!-3` will run the 3rd last command in your bash history
`!-1` is the same as `!!`

### Bang Search

`!ec` - runs the last command that starts with “ec” (likely echo).

`!?cho` - runs the last command that has “cho” anywhere in it (likely echo). Basically, a non-interactive version of `Ctrl-r` reverse searching.

### Bang Arguments

`!!:3` or `!:3` - expands to the third argument of the preceding command (change the number for the different arguments obviously)

`!$` - the last item of the previous command
`!^` - the first argument of the previous command (same as `!:1`)
`!*` - all arguments (non-command) from the previous command

### Bang Filenames (zsh)

Use `!:t` to strip the filename out of the last argument of the previous command.

`wget ftp://ruby-lang.org/pub/ruby/1.8/ruby-1.8.7-p330.tar.gz`
`tar xzvf !:t`

## Filepath expansion

The unix shell automatically expands file path patterns. When multiple files match, they are listed, separated by spaces.

### Star *

The star character matches 0 or more characters, apart from `/` (the directory separator.)

For example, on OSX:

```bash
echo ~/Do*
/Users/user/Documents /Users/user/Downloads

###  Question Mark ?

The question mark matches exactly one single character, apart from `/`.

```bash
echo /var/logs/nginx/error.log.?.gz
/var/logs/nginx/error.log.1.gz /var/logs/nginx/error.log.2.gz /var/logs/nginx/error.log.3.gz
```

### Brace Expansion `{}`

Unlike the `*` and `?` matchers, brace expansion will happen regardless of whether or not a file exists.

Brackets can be used to expand a list into a filepath:

```bash
echo {a,b,c}.txt
a.txt b.txt c.txt
```

Brackets can also deal with ranges:

```bash
echo error.{9..12}
error.9 error.10 error.11 error.12

echo {a..e}
a b c d e
```

## Zsh Specifics

`esc+'` will put single quotes around the current command

`esc+_` will insert the last argument of the previous command. release all the keys and press again to go back in history

`esc+q` will clear the line, but repaste that line into the next command (so you can do another command before it)

`cd one two` will replace all instnaces of `one` in the CWD with `two`