没有临时文件的两个外壳程序列表之间的交集

Question

Lots of questions has been put on the web about the result that I want. Imagine, you have got two lists in a shell script:

 LIST_ONE="key1 key2 key3 key4"
 LIST_TWO="key2 key3 key5"

I would like the intersection of this two lists:

 LIST_FIN="key2 key3"

I found some things to do like using comm command. But it always uses files, and I can't use temp files.

Thanks for your advice.

Answer 1

Use process substitution:

grep -o -f <(echo "$LIST_TWO" | tr ' ' '\n') <<< "$LIST_ONE" | xargs
key2 key3

Answer 2

How about something like this:

$ LIST_ONE="key1 key2 key3 key4"
$ LIST_TWO="key2 key3 key5"
$ comm -12 <(tr ' ' '\n' <<< "${LIST_ONE}" | sort) <(tr ' ' '\n' <<< "${LIST_TWO}" | sort)
key2
key3
$