Dynamic variable names based on value

Question

Probably a noob question, but I'm having a particular challenge where I want to dynamically generate variable names based on a value. Eg. If I'd require 3 variables, variable names to be incremented dynamically var_0,var_1,var_3 respectively.

The solution I have right now is barebones. I'm just using read -p get user input and save it to variable. So for 5 hosts, I've just duplicated this 5 times to get the job done, but not a clean solution. I was looking around and reading through declare and eval but haven't got anywhere

Thinking of a solution where I input no. of hosts first and this dynamically picks up and asks for user input based on number of hosts and saves to variables incremented dynamically

Any help is appreciated, cheers

Sounds like a job for an array (see BashFAQ #5). Use e.g. read var[0] to fill values, and "${var[0]}" to access it. — Gordon Davisson
– Gordon Davisson, Commented Apr 12, 2021 at 5:45

Socowi · Accepted Answer · 2021-04-12 20:49:03Z

1

Use arrays. However, you don't have to ask the user for the number of hosts. Let them enter as many hosts as they like and finish by entering an empty line:

echo "Please enter hosts, one per line."
echo "Press enter on an empty line to finish."
hosts=()
while read -p "host ${#hosts[@]}: " host && [ -n "$host" ]; do
  hosts+=("$host")
done
echo "Finished"

Alternatively, let the user enter all hosts on the same line separated by whitespace:

read -p "Please enter hosts, separated by whitespace: " -a hosts

To access the individual hosts use ${hosts[0]}, ${hosts[1]}, ..., ${hosts[${#hosts[@]}]}.
To list them all at once use ${hosts[@]}.

edited Apr 12, 2021 at 20:49

answered Apr 12, 2021 at 7:57

Socowi

27.9k4 gold badges41 silver badges72 bronze badges

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

Comments

Ivan · Accepted Answer · 2021-04-12 08:31:26Z

0

Use an array instead! But read can actualy create dynamic vars, just like this:

for i in {1..3}; do
    read -p 'helo: ' var_$i
done

answered Apr 12, 2021 at 8:31

Ivan

7,5111 gold badge22 silver badges27 bronze badges

Collectives™ on Stack Overflow

Dynamic variable names based on value

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related