Listing files using a variable filter-CodePudding

I'm trying to list files using filters in a shell bash.

This example works:

result=$(ls *{A1,A2}*.txt)

echo $result

file1_A1.txt,file2_A2.txt

But when puuting the filters into a variable, it doesn't work:

filter={A1,A2}
result=$(ls *"$filter"*.txt)
echo $result

ls: cannot access '{A1,A2}': No such file or directory

I'm using a wrong sintax. How can I fix it?

Best

CodePudding user response：

Using extended globbing :

shopt -s extglob

filter="A1|A2"
result=(*@($filter)*.txt)
echo "${result[@]}"

CodePudding user response：

You could use eval to achieve what you want (although I'm not a big fan of it; eval should be avoided whenever possible IMO):

filter="{A1,A2}"
result=$(eval "ls *$filter*.txt")
echo "$result"

There is no other way as brace expansion is done before any other expansion (e.g. variable expansion). See man bash, sections EXPANSION and Brace Expansion.

However, a possible workaround is given in this answer.