Question

I’m writting a bash wrapper to learn some scripting concepts. The idea is to write a script in bash and set it as a user’s shell at login.

I made a while loop that reads and evals user’s input, and then noticed that, whenever user typed CTRL + C, the script aborted so the user session ends.

To avoid this, I trapped SIGINT, doing nothing in the trap.

Now, the problem is that when you type CTRL + C at half of a command, it doesn’t get cancelled as one would do on bash – it just ignores CTRL + C.

So, if I type ping stockoverf^Cping stackoverflow.com, I get ping stockoverfping stackoverflow.com instead of the ping stackoverflow.com that I wanted.

Is there any way to do that?

#!/bin/bash

# let's trap SIGINT (CTRL + C)
trap "" SIGINT

while true
do
    read -e -p "$USER - SHIELD: `pwd`> " command
    history -s $command
    eval $command
done

Answer 1

You could use a tool like xdotool to send Ctrl-A (begin-of-line) Ctrl-K (delete-to-end-of-line) Return (to cleanup the line)

#!/bin/bash
trap "xdotool key Ctrl+A Ctrl+k Return" SIGINT;
unset command
while [ "$command" != "quit" ] ;do
    eval $command
    read -e -p "$USER - SHIELD: `pwd`> " command
  done
trap SIGINT

The please have a look a bash’s manual page, searching for “debug” keyword…

man -Pless\ +/debug bash