If you want to experiment with history expansion a bit, you can echo the result instead of executing it:

hostname:~/dir% ls /some/long/path/to/file_0.1-2_i386.changes
hostname:~/dir% echo !?ls?:s/-2/-3/
echo ls /some/long/path/to/file_0.1-3_i386.changes

In this case, what I wanted to do is repeat a long command that referenced a file with a version number in it — but I wanted to use a different version number (-3 instead of the previously given version -2).

History expansion uses “!” (“bang”, or exclamation point). If you want to select the previous command to expand based on a string match, “!?str” will find the previous command that contains “str”. If you want to substitute some part of that previous command, put another question mark on the end, add a colon, and use the the “s” modifier. In the example above, “!?ls?” means expand the previous command containing “ls”. The “:s/-2/-3/” means modify that expanded command to replace the occurrence of “-2″ with “-3″.

(Of course, to actually get all of that figured out and working, I had to iterate the sequence of commands above about a dozen times.)

Leave a comment with your favorite zsh history trick. Thanks!

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Set your prompt by setting $PROMPT. If you do PROMPT='foo ', the shell will give you a foo prompt for every command. Not terribly useful but you get the point.

There are a bunch of codes you can use in the value of PROMPT to get useful output. For example, %m gives the name of the machine you’re running on, and %~ gives the name of the current working directory. For a list of all the codes, check the “zshmisc” man page under the section “SIMPLE PROMPT ESCAPES”. Note that there are codes for boldface, underline, and colors here too.

The drawback to having all kinds of information in your prompt is that you limit the length of commands that you can enter without scrolling. Scrolling stinks because the command is harder to read. Enter the “right prompt”. Set RPS1 to contain the lengthy part of your prompt, and it will be displayed on the right margin of your terminal. Then when commands get long and encroach on the right prompt, it will conveniently disappear. Read Quentin’s comment on this zsh post.

Here’s a gotcha with RPS1 and fancy prompt formatting: gnome-terminal does not behave well when these are set. I’m trying out alternatives to see which will be better.

Lastly, a trick I picked up from Justin. Zsh provides hooks that you can use to do things before and after a command runs. Just define the functions preexec and precmd. This example sets the title of the xterm while a command is running:

function title() {
    # escape '%' chars in $1, make nonprintables visible
    local a=${(V)1//\%/\%\%}

    # Truncate command, and join lines.
    a=$(print -Pn "%40>...>$a" | tr -d "\n")

    case $TERM in
        screen*)
            print -Pn "\e]2;$a @ $2\a" # plain xterm title
            print -Pn "\ek$a\e\\"      # screen title (in ^A")
            print -Pn "\e_$2   \e\\"   # screen location
            ;;
        xterm*)
            print -Pn "\e]2;$a @ $2\a" # plain xterm title
            ;;
    esac
}

# precmd is called just before the prompt is printed
function precmd() {
    title "zsh" "%m:%55<...<%~"
}

# preexec is called just before any command line is executed
function preexec() {
    title "$1" "%m:%35<...<%~"
}

Update: Set variable a to local in function title above as suggested in the comment below.

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# This controls what the line editor considers a word. By default it
# includes '/', which makes it so that when I M-del (attempting to erase
# a directory in a path), I erase the whole path. Annoying.
# WORDCHARS='*?_-.[]~=/&;!#$%^(){}<>' # (default)
WORDCHARS='*?_-.[]~=&;!#$%^(){}<>'


After living with this for a while, I realize that I should probably remove the underscore too, since that’s what I was used to in bash.

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1. sudo aptitude install zsh
2. chsh /bin/zsh

That’s pretty simple.

Of course, you’re not running zsh yet… either logout and log back in or just run zsh at the prompt. You’ll get a series of prompts to configure a .zshrc. It only takes a few minutes, so run through the options and save the file.

Next up: setting a custom prompt.

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