type:tldr:b527e

The "type" command in Unix/Linux is used to determine the type of a command or if a command is an internal shell command or an external executable file. When used with the "-a" option, it displays all the locations where that command is found in the user's $PATH.

Now, let's break down the command "type -a ${command}":

• "type": The command itself.
• "-a": An option used with the "type" command to display all the locations where the specified command is found.
• "${command}": A placeholder that is meant to be replaced with the actual command you want to check.

For example, if you want to check the type and location of the "ls" command, you would replace "${command}" with "ls" and the command becomes "type -a ls". This will display all the locations where the "ls" command is found in the $PATH, indicating whether it is a built-in shell command or an external executable.