Using numbers in String Array for user input using bash

Question

I have a text file I am trying to read into an Array using Bash. Here are the contents of text file:

Vol12
Vol0
Vol2
Vol21

I want to extract the number from the above string and present it to the user to select the number to enter choice such:

12 - Vol12
0  - Vol0
2  - Vol2
21 - Vol21

User would enter 12 to select Vol12 or 2 to select Vol2 and use the selection to do further action.

I have been searching how to do this but here is what I have so far:

Vol="/Users/alex/Downloads/file.txt"

options=($(tail -n+1 $Vol | awk '{print $1}' | sort | uniq) All Quit)

for (( i = 0; i < ${#options[@]}; i++ )); do
    echo "$i - ${options[i]}"
done

echo -e "Enter number corresponding to the Volume snapshot you want to restore: \n"
read vol

}

Following output is what I am getting with above code:

OPTIONS MENU
0 - Vol12
1 - Vol0
2 - Vol2
3 - Vol21
4 - All
5 - Quit
Enter number corresponding to the Volume snapshot you want to restore:

How can I get the output to show like following and able to select 12 or 0 ?

12 - Vol12
0  - Vol0
2  - Vol2
21 - Vol21

Please help

Quasímodo · Accepted Answer · 2020-04-30 19:35:39Z

2

You can use associative arrays:

#!/bin/bash
Vol="/Users/alex/Downloads/file.txt"
declare -a arr

#Loop reads each line of the file
while IFS= read -r line; do
    n=${line##*[!0-9]}       #Gets the number at the end of this line
    arr[$n]=$line            #Uses it as the key to the array, the content being the whole line
    echo "$n - $line"
done < "$Vol"

read -p "Select one from above. " vol
echo "You selected ${arr[vol]}."

For example (I saved it as sh.sh):

$ ./sh.sh
12 - Vol12
0 - Vol0
2 - Vol2
21 - Vol21
Select one from above. 2
You selected Vol2.

edited Apr 30, 2020 at 19:35

answered Apr 30, 2020 at 19:23

Quasímodo

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6 Comments

NetSystemAdmin Over a year ago

Thanks. Would it be easier to extract the number at the end of Vol##? So Vol has 3 characters,(Vol##). How can I extract the number after Vol?

Quasímodo Over a year ago

@NetSystemAdmin You're welcome. I'm not sure I understand your question. It will work with Vol1, Vol11, Vol111, ...

Jetchisel Over a year ago

@NetSystemAdmin if this works for you then you need to accept this and up vote...

NetSystemAdmin Over a year ago

I went a different route. This works: for (( i = 0; i < ${#options[@]}; i++ )); do num=${options[i]#Vol} echo "$num - ${options[i]}" done

Léa Gris Over a year ago

It is possible to fill the array in one go with: declare -a arr="($(<"$Vol" xargs -n 1 -d '\n' bash -c 'printf "[%d]=%q\n" "${0##*[^[:digit:]]}" "$0"'))"

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