Shell tips and tricks

Its been a while since I’ve written a blog post and I thought I’d dedicate this one to some of the tricks I’ve used when working with my shell in my terminal that make me more productive on a daily basis.

To start I like to use zsh because it has a lot of features that few other shells have such as:

• autocomplete commands such as kill with the list of currently running processes and it does this for quite a few other commands
• shared history (among different zsh sessions)
• hook functions (we’ll talk about these below)
• many more features…

There are a ton of them but the ones that I find the most useful are the hook functions which you can read more about here. I find myself using the hook functions to make my life easier every day when working. The first very simple set of things I do with the hooks is to use the chpwd hook to automatically change the title of my terminal to match the name of the directory I’m currently in. In my .zshrc I have:

set_window_title() { 
    echo -ne "\033]0;"$PWD"\007"
}

# set the title on the first pass through here
set_window_title

# update the console title on directory change
chpwd() {
    set_window_title
}

The previous will make it so that your title matches the current working directory at all times but it won’t handle well the situation where the current working directory name is super long. So I’ve devised a slightly different solution where I’ll truncate the longer title and put a few dots and show the last part of the path which is more important to the user, like so:

pad() {
    if [ ${#1} -lt $2 ]
    then
        pad "$1 " "$2"
    else
        echo "$1" fi
}

ltrunc() {
    FILL="..."
    if [ "$3" != "" ]
    then
        FILL="$3"
    fi
    print -P "%$2<$FILL<$1"
}

lpad_title(){
    VAR=`ltrunc "$1" 32`
    pad "$VAR" 32
}

set_window_title() { 
    export PREFIX=""
    if [ "$VIRTUAL_ENV" != "" ] 
    then
        VENV=$(basename $VIRTUAL_ENV) 
        export PREFIX="($VENV)"
    fi

    STRPATH=`lpad_title "$PWD"`
    echo -ne "\033]0;"${PREFIX}${STRPATH}"\007"
}

Its definitely more complex but makes for better looking titles when the directo name is longer than 32 characters.

The next trick I like to use is to wrap “long” running commands so I can get desktop notifications when the’ve completed. This can be done on any shell really since I just uses aliases to achieve the desired effect. This is an example implementation:

NOTIFY_CMDS=(grunt npm bower git make ant python)

run_cmd() {
    $@
    CMD=`echo $@ | tr -d '\r'`
    RETURN =$?
    if [ $RETURN == 0 ]
    then
        notify-send -t=5000 "Shell" "[$CMD], finished"
    else
        notify-send -t=5000 "Shell" "[$CMD], finished with failure"
    fi
    return $RETURN
}

for CMD in "${NOTIFY_CMDS[@]}"
do
    alias $CMD="run_cmd $CMD"
done

The above makes it so that the commands in the variable NOTIFY_CMDS will be aliased to run through the run_cmd function that can then check the return code and in my case use libnotify through notify-send to show the notifications on my desktop for those commands and the status of how they exited.

So why do I find the notification mechanism above so useful ? Well I like to start those long running tasks and then move onto something else while things are building, compiling or copying and not have to constantly come back to the window to see if the command has completed. With this notification I know I’ll get a little popup that I can look at quickly and know the result right then and there without having to switch back to another window.