Bash Multiple conditions in while loop

Question

I'm trying to get a simple while loop working in bash that uses four conditions, but after trying many different syntax from various forums, I can't find solution. When i write 'Prod' or 'Dev' or 'Admin', i stay in the loop.

while [ -z $vmProfil ] || [ $vmProfil != 'Prod' ] || [ $vmProfil != "Dev" ] || [ $vmProfil != "Admin" ]
do 
    read -p 'Choose vm profil between Prod, Dev or Admin :' vmProfil
done

chepner · Accepted Answer · 2020-02-10 20:27:59Z

3

You are using || where you should be using &&; no matter what value vmProfil has, at least on of the != conditions must be true.

while [ -z "$vmProfil" ] || { [ "$vmProfil" != 'Prod' ] && [ "$vmProfil" != "Dev" ] && [ "$vmProfil" != "Admin" ]; }

You can also check negate the result of checking if any condition is true.

while [ -z "$vmProfil" ] || ! { [ "$vmProfil" = 'Prod' ] || [ "$vmProfil" = "Dev" ] || [ "$vmProfil" = "Admin" ]; }

I would write this as an infinite loop with an explicit break, though.

while :; do
  read -p '...' vmProfil
  case $vmProfil in
    Prod|Dev|Admin) break ;;
  esac
done

edited Feb 10, 2020 at 20:27

answered Feb 10, 2020 at 18:25

chepner

538k77 gold badges594 silver badges746 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

Jason Over a year ago

I think you got the logic backwards from the question: "When i write 'Prod' or 'Dev' or 'Admin', i stay in the loop."

chepner Over a year ago

That's what the OP's code does now, which is the opposite of what the prompt implies they want.

Jason Over a year ago

You are correct. OP's logic in the question is backwards. The logic he is attempting to do in his code was right. +1

Gordon Davisson Over a year ago

Also, the unquoted variables are a possible problem, especially in [ -z $vmProfil ]-- it'll probably work, but mostly by accident. Double-quote variable references to avoid weird parsing problems.

Walter A Over a year ago

Thanks to the quoting "$vmProfil" the first check -z "$vmProfil" is redundant. I do like the case solution, +1

|

Collectives™ on Stack Overflow

Bash Multiple conditions in while loop

1 Answer 1

6 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

6 Comments

Your Answer

Sign up or log in

Post as a guest

Related