Edit shell script while it's running

user_32840 0
Viewed 55018

Can you edit a shell script while it's running and have the changes affect the running script?

I'm curious about the specific case of a csh script I have that batch runs a bunch of different build flavors and runs all night. If something occurs to me mid operation, I'd like to go in and add additional commands, or comment out un-executed ones.

If not possible, is there any shell or batch-mechanism that would allow me to do this?

Of course I've tried it, but it will be hours before I see if it worked or not, and I'm curious about what's happening or not happening behind the scenes.

csh shell linux
11 Answers

Good question! Hope this simple script helps

#!/bin/sh
echo "Waiting..."
echo "echo \"Success! Edits to a .sh while it executes do affect the executing script! I added this line to myself during execution\"  " >> ${0}
sleep 5
echo "When I was run, this was the last line"

It does seem under linux that changes made to an executing .sh are enacted by the executing script, if you can type fast enough!

user_51656180

An interesting side note - if you are running a Python script it does not change. (This is probably blatantly obvious to anyone who understands how shell runs Python scripts, but thought it might be a useful reminder for someone looking for this functionality.)

I created:

#!/usr/bin/env python3
import time
print('Starts')
time.sleep(10)
print('Finishes unchanged')

Then in another shell, while this is sleeping, edit the last line. When this completes it displays the unaltered line, presumably because it is running a .pyc? Same happens on Ubuntu and macOS.

user_13089670

Use Zsh instead for your scripting.

AFAICT, Zsh does not exhibit this frustrating behavior.

user_3265160
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