Bourne Shell scripting help

JimmyCrackCorn!

Checking an enviroment variable is set

What i can do simply in bash with
if [ -z $ENV_VER ] ; then



i have tied this on borne and cant get it to work wothout


"sh: ENV_VER: Parameter not set."


I have tried:(what i can remember trying)

if [-n ${var:-x}]

[ ! -z $var ] && echo "set" || echo "not"

${var:-'SomeDefault'}

if [ "X${VAR}" != "X" ] ;then echo "hi" ;fi;

Talon.ie

This might help http://stackoverflow.com/questions/307503/whats-the-best-way-to-check-that-environment-variables-are-set-in-unix-shellscri

bullpost

If you're still stuck I think you can use the test command to do this iirc.

Look up the man page for test but it should be something like:

if test $A then ......

croo

You sure
if [ "X${VAR}" != "X" ] ;then echo "hi" ;fi;
doesn't work?

As is, it would only display "hi" when the VAR is set! Rather than when it is empty as you initially said. But I'm guessing that is a typo?
if [ "X${VAR}" == "X" ] ;then echo "hi" ;fi;
to say "hi" when VAR is not set

A great way to test this things I find is to enabling debugging with set -x

set -x
if [ "X${VAR}" == "X" ] ;then echo "hi" ;fi;

then at the prompt
$ export VAR= (just to be sure!)
$ ./script.sh
++ ''
++ echo hi
hi

$ export VAR=yes
$ ./script.sh
++ ''

JimmyCrackCorn!

[ -z $A'' ]

Works