How do I re-redirect stdin in a Unix or Linux shell script?

while read usrname
 do
   lsh $usrname
 done < $file

This is a classic shell scripting question because once you redirect standard input to be from a file (as you do with the < $file after the done statement) then subshells, functions and everything else also inherit the changed file descriptor.

The good news is that the solution is straightforward: just change standard input (stdin for you Unix geeks out there) to the keyboard, aka "/dev/tty". Here's a simple little script that demonstrates what I'm talking about:

It's obviously not exactly what you have, but you can see how you can use the redirect in the while loop to pull input from a file (in this case I'm using $1 for simplicity). and then notice how the read statement has an input redirect too: < /dev/tty.

Try that with your application and see if it works out!

Avid shell script programmers will doubtless be psyched to learn more about my best-selling Wicked Cool Shell Scripts, a collection of over 100 fun and educational shell scripts.