csh idioms to check for environment variable existence?

Question

I've got a few csh scripts where I need to check that certain environment variables are set before I start doing stuff, so I do this sort of thing:

if ! $?STATE then
    echo "Need to set STATE"
    exit 1
endif

if ! $?DEST then
    echo "Need to set DEST"
    exit 1
endif

which is a lot of typing. Is there a more elegant idiom for checking whether or not an environment variable is already set?

Notes:

This question is quite similar, but specifically asks about solutions in bash.
I'm not looking for people to advise me to stay away from csh because it's cursed, scary, or bash is better. I'm specifically interested in a more elegant solution than what I'm using now.

[This newer, similar question](http://stackoverflow.com/questions/13343392/how-to-check-if-an-environment-variable-is-either-unset-or-set-to-the-empty-stri) also show how to check in an expression context where if/else/endif is not possible — cfi, Oct 01 '15 at 13:42

score 22 · Answer 1 · answered Feb 25 '10 at 18:19

22

I think the way you're doing it (an if statement with a condition using the $?VAR syntax, which evaluates to 1 if the variable is set, and 0 otherwise) is probably the most idiomatic csh construct that does what you want.

answered Feb 25 '10 at 18:19

Jim Lewis

43,505
7
82
96

score -6 · Answer 2 · edited Aug 28 '14 at 16:16

-6

Try the following:

[ -z STATE ] && echo "Need to set STATE"

[ ! -z DEST  ] && echo "Need to set STATE"

edited Aug 28 '14 at 16:16

smagnan

1,197
15
29

answered Aug 28 '14 at 15:53

David Thomas Sr.

1
1

3

It's not clear what you're trying to say here - you have two opposite pieces of logic printing the same message. – nobody Aug 28 '14 at 16:26
3

In any case this is not csh – supergra Apr 03 '15 at 00:06

csh idioms to check for environment variable existence?

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