I wonder is there any program that can take a bash script as input and print out all bash commands it will run? A program that would unroll loops, expand environment variables and generally not perform any destructive action nor call any external binaries. It’s like a dry run of sorts.
Edit: I’ve created a script that updates ufw rules. I wanted to use multiple IP addresses as a range and multiple interfaces like this:
ufw add limit in on eth0,eth1 from 172.16.0.0/12,10.0.0.0/8,192.168.0.0/16 to any port 22 comment "allow SSH on LAN"
but ufw does not support setting multiple interfaces and multiple interfaces comma separated like ports so I created a script instead.
# ...
lan_ip_range=('172.16.0.0/12' '10.0.0.0/8' '192.168.0.0/16')
for ip_lan in "${lan_ip_range[@]}"; do
# SSH
ufw add limit in on eth0 from "$ip_lan" to any port 22 comment "allow SSH on LAN"
ufw add limit in on eth1 from "$ip_lan" to any port 22 comment "allow SSH on LAN"
# ...
done
I want to make sure it does what I expect it to do. so expected output should be something like this:
ufw add limit in on eth0 from 172.16.0.0/12 to any port 22 comment "allow SSH on LAN"
ufw add limit in on eth0 from 10.0.0.0/8 to any port 22 comment "allow SSH on LAN"
ufw add limit in on eth0 from 192.168.0.0/16 to any port 22 comment "allow SSH on LAN"
This is way over complicating the issue. Just replace the actual commands you’re worried about with printf. You can even format it so it prints the exact command you WOULD run.
If you want to get fancy with add a flag to you script like —test or —execute or something where it either prints what it’s going to run or actually executes them.
yes, I could do that but If I ever would check some other script this way, a script I didn’t write my self, then I would need to edit that as well. I’m now thinking of something like a container that runs a script and replaces command not found errors with an echo of the command in question.