Bash - reverse order of curly bracket resolution

Question

Such code

$ ls {a,b}{c,d}

runs ls command on following files: ac, ad, bc, bd.
Is there a simple way to reverse resolution order and generate such sequence: ac, bc,ad, bd?

edit
I want to run grep on particular subset of files inside a subset of directories like this:

$ grep 'find this' {sub_dir_one,sub_dir_two}/some_loc/{file_one,file_two}

I want lines from both file_one, then both file_two with respect to sub_dir_one and sub_dir_two order.

I just wonder if there's some nice trick which prevents me from using loop.

Other than changing the brace expansion itself to `{a,b}c {a,b}d`? — Kusalananda, Aug 29 '19 at 14:12
@Kusalananda yes it's general exampl, I'm going to update question. — Jakub Kuszneruk, Aug 29 '19 at 14:15
I don't understand your edit. You want the `grep` to visit the files in a particular order? — Kusalananda, Aug 29 '19 at 14:44
I remember distinctly that this was already asked, but I suck at searching. Anyways, `eval echo '{a,b}'{c,d}` — , Aug 29 '19 at 15:37
here it is: https://unix.stackexchange.com/questions/525921/apply-brace-expansion-in-reverse-order — , Aug 29 '19 at 15:45
@Kusalananda yes, because I need output to be sorted in particular order. — Jakub Kuszneruk, Aug 30 '19 at 08:19

score 2 · Accepted Answer · answered Aug 29 '19 at 14:37

According to bash man page, in the Brace expansion paragraph,

The results of each expanded string are not sorted; left to right order is preserved.

So an alternative is to use a for loop:

for i in file_one file_two; do
   grep 'find this' {sub_dir_one,sub_dir_two}/some_loc/"$i"
done

Bash - reverse order of curly bracket resolution

1 Answers1