mjhjmtu

I declared var0, var1, var2, var3 with a for loop. How do I echo the vars inside that for loop? Here's the code.

#!/bin/bash

for i in 0..3
do
 export var$i=$i
done;

There i defined var0, var1, var2, var3.. how do i access them in a loop?

i tried the following

for i in 0..3
do
 echo $var$i
 tmpvar=var$i
 echo $tmpvar
done

but none gave me the values of var0,var1...
first echo just printed '0,1,2,3', second echo printed 'var0,var1,var2,var3'
what do i do? I want the values..

You can use eval for that:

$ var1='< 1 >'; var2='< 2 >'; var3='< 3 >'
$ for i in 1 2 3; do eval echo $var$i; done
$ for i in 1 2 3; do eval "echo $var$i"; done
$ for i in 1 2 3; do eval 'echo $var'$i; done
$ for i in 1 2 3; do eval "v=$var$i"; echo "$v"; done

Take care with the quoting and escaping. If the values contain whitespace or glob characters, the first three will split the values on whitespace, and then expand any filenames that match the glob. This may or may not be what you want. For example:

$ var1='< x >' var2='< * >'
$ for i in 1 2; do eval echo $var$i; done
< x >
< [list of filenames in current directory] >

(Note that the double spaces around x were collapsed to single spaces since echo received <, x and > as separate arguments.)

To work around that, you need to make sure the variable expansion is quoted within the eval, e.g.:

$ for i in 1 2; do eval echo "$var"$i""; done
< x >
< * >

_{(quote the $i too, as above, unless you know IFS doesn't contain any digits.)}

Given,

var0=a
var1=b
var2=c

with ksh93 or bash 4.3 or newer, you can use a nameref to point at the individual variables:

for i in 0 1 2; do
 typeset -n p="var$i"
 echo "$p"
done

But unless you explicitly need the variables as separate scalars (for example because you passed them through the environment), and are not using a strictly standard shell, but Bash or ksh, you should use an array instead:

#!/bin/bash
a=(a b c)
for i in 0 1 2; do
 echo "$a[i]"
done

Or ignoring the indexes:

for x in "$a[@]"; do
 echo "$x"
done

(Zsh, of course, has arrays too, it just starts indexing from 1 by default so the first one doesn't work directly.)