CODEWITHSUNDEEP
regexstringbash
HotDogCannon
HotDogCannon

Reputation: 2386

Return digits from a string in bash shell

i'd like to return only the digits from a string variable in bash shell. For example, for:

#!/bin/sh
file="./file_02.txt"
file_num_tag=?????????????????
echo $file_num_tag

...i'd like to return 

>>> 02

I know this is super trivial, but I'm confusing myself searching around for answers and I'd like to know the best way to do it.

Upvotes: 3

Views: 60

Answers (1)

anubhava
anubhava

Reputation: 784938

You can use this BASH string replacement:

file="./file_02.txt"
echo "${file//[^[:digit:]]}"
02

[^[:digit:]] will match and remove all non-digits from your string file.

Or using tr (if not using BASH):

num=`echo "$file" | tr -cd '[[:digit:]]'`

Upvotes: 6

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