Using RegEx with variable within bash if [[ ]]


 
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# 1  
Old 06-01-2016
Using RegEx with variable within bash if [[ ]]

I stumbled upon a problem, which I simplified to this:

There is a list of numbers, stored in variable $LIST, lets use `seq 5 25` for demonstration.

There is a number that should be compared against this list. For demonstration I use user input - read VALUE

I am trying to compare RegEx ^$VALUE$ to $LIST. it works from command line:
Code:
> LIST=`seq 5 25`
> VALUE=6
> echo "$LIST" | grep -e ^$VALUE$
6

But same comparison does not work within [[ ]].

overall script looks like this:

Code:
#/bin/bash
LIST=`seq 5 255`
echo  Please input number:
read VALUE
if [[ "$LIST" =~ "^$VALUE$" ]]
then 
        echo Value is in range 
else
        echo Value is not in range
fi

Please help to fix right site of comparison:
Code:
 if [[ "$LIST" =~ "^$VALUE$" ]]

# 2  
Old 06-01-2016
The ^ designates the very begin of the string, which in your sample would be 5 . The $ marks the very end, 5 again in your sample.
Try

Code:
[[ $LIST =~ [[:space:]]$VALUE[[:space:]] ]] && echo Value is in range || echo Value out of range

This User Gave Thanks to RudiC For This Post:
# 3  
Old 06-02-2016
Thanks!
I used ^..$ because echoing variable returns different results with and without quotes:
Code:
 echo $LIST 
5 6 7 8 9 10 11 12 13 14 15 16 17 18

echo "$LIST" 
5
6
7
8

I thought same thing would apply here




Moderator's Comments:
Mod Comment Please use code tags as required by forum rules!

Last edited by RudiC; 06-02-2016 at 07:42 AM.. Reason: Added code tags.
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