comb

Combine the lines from two files in every combination.

Usage

▶ comb -h
Combine the lines from two files in every combination

Usage:
  comb [OPTIONS] <prefixfile> <suffixfile>

Options:
  -f, --flip             Flip mode (order by suffix)
  -s, --separator <str>  String to place between prefix and suffix

Example

Normal mode:

▶ cat prefixes
1
2
▶ cat suffixes
A
B
C
▶ comb prefixes suffixes
1A
1B
1C
2A
2B
2C

Flip mode (order by suffix):

▶ comb --flip prefixes suffixes
1A
2A
1B
2B
1C
2C

Separator:

▶ comb --separator="-" prefixes suffixes
1-A
1-B
1-C
2-A
2-B
2-C

Can't you just do this with a couple of nested bash loops?

Yes, but it's a PITA to type.