Shell Programming and Scripting

What is the best way of having a script that has it's own commands, which can be called at any stage in the script.
I'm sure there is a technical term for this type of CLI app which can help my search but I can't remember it.

Is using trap the best way of doing this.

Is a function what your refering to?

Code:

function myfunction
{
  # your code here
}
...

function param1 param2

sorry about the ambiguous title and question. Perhaps giving my specific use of this case might help, basically what I have is a script which finds all duplicates in a directory and asks "delete file?" with each set of duplicates. however during this I might find that I want to ignore all files in, say, the Mozilla directory. So I might issue a command like

> ignore "./Mozilla"

In the middle of the script. Is using trap with a function like "read...etc, case ...ignore...etc" the usual way of doing this? For example there are apps that have their own commands and their command line is prefixed by
>
is using trap to enter this mode in the middle of a script a good idea?

No tips, anyone? I guess I'll just use trap.

I do not think there is a need for trap, since you are looping through a list of files and/or directories and checking user input anyway for every delete. So instead of checking for y/n only you could check for "ignore" and take it from there.

good point, that sounds even better.

There is one problem I have now though, I'm not asking for yes or no but a list of numbers that correspond to filenames in the shown set of duplicates. So I guess my follow up question is: what is the best way of checking whether the user input is a list of numbers separated by spaces, or not?

You can check this with a case statement, e.g.:

Code:

case $input in)
  ignore*) bla bla 2 ;;
  *)  for i in $input
      do
        delete corresponding file or directory
      done ;;
esac