I want to Extract the date from this string in Bash and save it to a variable-CodePudding

I want to Extract the date from this string in Bash and save it to a variable but the problem im facing is there are many - and I cant use ##

7_I-9112135749087-ZA_23-20211021-085359_2051521761_0000.zip

I want to extract 20211021 Please

Thanks

CodePudding user response：

Assuming the filenames are always in the same format, you can do this in one of two ways.

Using just string manipulation:

$ file="7_I-9112135749087-ZA_23-20211021-085359_2051521761_0000.zip";

$ file=${file%-*};  # remove last dash through end of string
$ file=${file##*-}; # remove everything up to last remaining dash

$ echo "$file";
20211021

Using an array:

$ file="7_I-9112135749087-ZA_23-20211021-085359_2051521761_0000.zip";
$ IFS="-" read -ra parts <<< "$file";  # split into 0-based array using "-" as delimiter
$ echo ${parts[3]}; # 4th index
20211021

CodePudding user response：

Since there is a visible separator (-), I would simply use cut to select the fourth range:
$ var=$(echo "7_I-9112135749087-ZA_23-20211021-085359_2051521761_0000.zip" | cut -d "-" -f4)