cal command not working

Question

I am trying to access calendar by "cal" command in terminal but there is error message.

hetz@hetz-Lappy:~$ cal
bash: cal: command not found

Answer 1

I would recommend first installing command-not-found to help with errors like this:

sudo apt install command-not-found

Then open a new terminal to ensure its features will be available within it.

Now when you try to run cal, you will get an more useful error message which will tell you which package to install:

Command 'cal' not found, but can be installed with:
sudo apt install ncal

Answer 2

Install the ncal package:

sudo apt install ncal

If you have command-not-found installed and enabled (which it is by default in Bash) you should get a suggestion to install the package. If you use Zsh, copy these lines from /etc/bash.bashrc to your .zshrc (or enable a relevant plugin for your Zsh framework):

# if the command-not-found package is installed, use it
if [ -x /usr/lib/command-not-found -o -x /usr/share/command-not-found/command-not-found ]; then
    function command_not_found_handle {
        # check because c-n-f could've been removed in the meantime
        if [ -x /usr/lib/command-not-found ]; then
           /usr/lib/command-not-found -- "$1"
           return $?
        elif [ -x /usr/share/command-not-found/command-not-found ]; then
           /usr/share/command-not-found/command-not-found -- "$1"
           return $?
        else
           printf "%s: command not found\n" "$1" >&2
           return 127
        fi
    }
fi