topic Re: variable substitution in Operating System - HP-UX

variable substitution

Dave Peeke — Fri, 01 Dec 2000 16:05:12 GMT

I am trying in a script to use a variable within a variable and I'm having trouble with the syntax e.g:

xxxa=test1
xxxb=test2
xxxc=test3
for i in a b c
do
echo "$xxx$i"
done

where I want the result to be test1, test2, test3 (not xxxa, xxxb, xxxc). Can anyone help me with the syntax for the echo line please?

Re: variable substitution

Darrel Louis — Fri, 01 Dec 2000 16:11:13 GMT

I've done a similar test:

a=test1
b=test2
c=test3
for i in $a $b $c
do
echo "$i"
done

The variables you should specify with $xxxa etc.

Is this what you want?

Re: variable substitution

Dave Peeke — Fri, 01 Dec 2000 16:21:55 GMT

Darrel,

Not quite as I don't want to specify the whole variable in the for statement. The previously assigned variables need to be longer and I will actually be using a number to reference them in a loop i.e. disk1 disk2 disk3 etc and the loop count will be used for the number i.e. for i in 1 2 3 4.

Re: variable substitution

Tom Danzig — Fri, 01 Dec 2000 16:22:02 GMT

Try putting curly braces around the variable name. Required if the variable name adjoins additional text. Such as:

echo "${xxx}${i}"

Re: variable substitution

Dave Peeke — Fri, 01 Dec 2000 16:28:10 GMT

Tom,

Thanks, but it doesn't fix the problem as I get a,b,c rather than the contents of xxxa, xxxb, xxxc.

Re: variable substitution

Kenneth Platz — Fri, 01 Dec 2000 17:40:12 GMT

This should work:

#!/bin/sh

xxxa="test 1"
xxxb="test 2"
xxxc="test 3"

for I in a b c
do
eval "echo \$xxx$I"
done

Re: variable substitution

Victor BERRIDGE — Fri, 01 Dec 2000 17:45:47 GMT

I dont think you can echo a variable that is itself an echo of another, so I dont see any solution except Darrels,which mean you need a step between:
xxxa=test1
xxxb=test2
xxxc=test3

a=$xxxa
b=$xxxb
c=$xxxc
for i in $a $b $c
do
echo "$i"
done

Good luck

Victor

Re: variable substitution

Pramod_4 — Fri, 01 Dec 2000 19:00:47 GMT

Hi,

Assign the variable as follows:

xxx[1]=tiger ; xxx[2]=lion ; xxx[3]=cat

If you assign as above then the following would do the job:

for i in ${xxx[@]} ; do

echo $i

done

Above should display:
tiger
lion
cat

Best of luck,

Pramod

Re: variable substitution

Alan Riggs — Fri, 01 Dec 2000 19:13:23 GMT

I agree, this case seems quite appropriate for an array variable. You can even set teh variables easily using set -A

Re: variable substitution

Shannon Petry — Sat, 02 Dec 2000 12:27:59 GMT

Not that your problem is not fixed already.....Some good things were posted. Another thing I do occasionally is use a little used command "eval". I.E.
xxxa=1
xxxb=2
xxxc=3
for i in $a $b $c ; do
eval echo "\$xxx$i"
done

The eval tells the shell to expand all of the variables prior to excecuting the "echo".
This is why Kenneths example works!

Regards,
Shannon