[SOLVED] unable to concatenate the variable dynamically

shravee · 02-13-2018, 11:24 AM

i have few variables defined in my env file.
for eg, CH=/this/is/first CH2=/this/is/second

i am scanning for few files using a script in a while loop with i as a counter.

echo $CH gives the value of the path. /this/is/first

while [ i equals to 2 ]
do

echo $CH$i is giving me the value of the path /this/is/first2 ( expected is /this/is/second)

done

how do i get this taken care dynamically.

i want CH to be appended with the "i" dynamically so that it becomes to CH2 and then finally gives the value of $CH2

i have many more such variables to be taken care. kind of stuck here.

rknichols · 02-13-2018, 12:24 PM

What you need is variable indirection.

Code:

Varname=CH$i
echo ${!Varname}

shravee · 02-13-2018, 01:11 PM

did not work. am i missing something.

1st attempt:

/ $ echo varname=CH$i
varname=CH2
/ $ echo ${!varname}
varname

2nd attempt:

/ $ pwd
/
/ $ echo $i
2
/ $ echo $CH2
/cognos/webcontent/ibm/c10_2_1_p17300
/ $ var=CH$i; echo ${!var}
var
/ $

rknichols · 02-13-2018, 02:56 PM

What shell are you using?

Code:

$ CH2=/path/to/some/file
$ i=2
$ var=CH$i; echo ${!var}
/path/to/some/file
$ echo $BASH_VERSION
4.1.2(2)-release

shravee · 02-13-2018, 03:26 PM

/cognos $ echo $SHELL
/bin/ksh

shravee · 02-13-2018, 03:38 PM

it worked when i entered bash and turned into bash-3.2$ prompt.

do i need to this all the time. moreover, does it work automatically in a script.

rknichols · 02-13-2018, 03:44 PM

Just insert a line "#!/bin/bash" as the very first line in the file and it should work just fine. Absent that line, your current shell will try to fork a copy of itself to run the script, and obviously ksh does not support that form of variable indirection.