Blog Post Publish Date: 2026/10/28

Hacking Your Zsh Terminal with Custom Widgets#

This blog post explains how to create custom Zsh widgets by registering shell functions to keyboard shortcuts powered by the Zsh Line Editor (ZLE).

Understand the Basics#

The idea is simple: you create a Zsh function and register it to a custom keyboard shortcut using the zle -N and bindkey commands. There are some special ZLE parameters that are made available to Zsh functions when they are called as widgets. The four main variables in this case are BUFFER that is the entire contents of the command line, CURSOR that is the cursor position, represented as an integer offset into BUFFER, along with LBUFFER and RBUFFER.

To understand these variables in practice, let’s create a function called debug-hook-variables and bind it to the Ctrl+x shortcut. This function will print the values of the variables:

# zsh function for debugging reserved variables
function debug-hook-variables() {
  echo 
  echo ">>> BUFFER:   $BUFFER"
  echo ">>> RBUFFER:  $RBUFFER"
  echo ">>> LBUFFER:  $LBUFFER"
  echo ">>> CURSOR:   $CURSOR"
}

# register the function as a ZLE widget
zle -N debug-hook-variables

# check if "debug-hook-variables" are registered as widget
zle -al | grep debug-hook-variables

# define "Ctrl+x" shortcut for "debug-hook-variables" widget
bindkey '^X' debug-hook-variables

# list all widgets with shortcut defined
bindkey -L

Now, type anything at your prompt and press Ctrl+x. In this example, with your cursor positioned after definitely and pressed Ctrl+x, the output will be like:

$ definitely| maybe  # press `Ctrl+x`

>>> BUFFER:   definitely maybe
>>> RBUFFER:   maybe
>>> LBUFFER:  definitely
>>> CURSOR:   10

Practical Example: Repeated Command Execution#

Now, let’s implement an alternative to the $ watch command that can behave unexpectedly when executing aliases such as kgp (more details in this Stack Overflow thread). The goal of this widget is to execute a command repeatedly every two seconds when you press Ctrl+x, while supporting aliases.

function repeat-command-widget() {
  while true; do
    clear
    eval "$BUFFER"
    sleep 2
  done
}

zle -N repeat-command-widget
bindkey '^X' repeat-command-widget

You can test the widget by typing the following command and pressing Ctrl+x:

kgp     
### press `Ctrl+x`
### stop execution by `Ctrl+c`

The kgp command is executed in a loop every two seconds until you press Ctrl+c, just like watch "kubectl get pods".

How to Register the Widget#

Built-in ZLE widgets can be configured using standard bindkey bindings. For custom Zsh widgets, we need to register the function, declare it via zle -N, and bind its keyboard shortcut in the ~/.zshrc file.

# ~/.zshrc

# define the function
function repeat-command-widget() {
  while true; do
    clear
    eval "$BUFFER"
    sleep 2
  done
}

# register funtion as a widget
zle -N repeat-command-widget

# define Ctrl+x to execute "repeat-command-widget" command
bindkey '^X' repeat-command-widget

The custom Ctrl+x shortcut will be available in new Zsh sessions.

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