Unix shell script - variable substitution inside another and concatenate values to the same variable

Question

I have the below requirement to concatenate the value of a variable to its own variable and create one array:

Table=CRS
Job=JOBNAME
gen_job_$Table=GENERATEDJOB
gen_job_$TABLE=$Job,${gen_job_${Table}}
echo ${gen_job_${Table}} should give JOBNAME,GENERATEDJOB

I tried using the eval function also as below:

eval gen_job_$Table=$job,eval echo \$gen_job_$Table

However, I am not able to display the final result.

In the line gen_job_$Table=GENERATEDJOB, are you using a dollar sign inside a variable name? I don't actually know if that's valid. I tried it, and was given an error. — Guest
– Guest, Commented Sep 10, 2017 at 10:27
You can do something similar with indirection, e.g. var1=10; a=1; str=var$a; echo ${!str} Output is 10 — David C. Rankin
– David C. Rankin, Commented Sep 10, 2017 at 11:00

Eric Renouf · Accepted Answer · 2017-09-10 11:00:17Z

1

You perhaps just want to consider using an array for a situation like this (and I recommend reading this page, however, if you want to dynamically build your variable names it is possible. To set a variable whose name is stored in another variable use printf -v like

table=CRS
job=JOBNAME
holds_name="gen_job_$Table"
printf -v "$holds_name" 'GENERATEDJOB'

Then when you want to access the variable whose name is set in holds_name you can use indirection:

printf '%s,%s\n' "$job" "${!holds_name}"

Using braces around the variable name, if the first character inside the brace is ! then the rest of the word is treated as the name of a variable that is expanded to find the name of the actual variable whose value should be used.

answered Sep 10, 2017 at 11:00

Eric Renouf

14.6k3 gold badges53 silver badges73 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Unix shell script - variable substitution inside another and concatenate values to the same variable

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related