Using regex capture group appended with underscore leads to erroneously named files

[ayoisaiah]

Using regex capture group appended with underscore leads to erroneously named files

[ayoisaiah]

Thanks for reporting this, I have been able to reproduce it. I will investigate the problem and find a fix.

In the meantime, you can do something like this:

f2 -f '(.*)\d.txt' -r '$1 %02d{{ext}}' -f ' ' -r '_'

┌──────────────────────────────────┐
| ORIGINAL  | RENAMED     | STATUS |
| ******************************** |
| test1.txt | test_01.txt | ok     |
| test2.txt | test_02.txt | ok     |
| test3.txt | test_03.txt | ok     |
└──────────────────────────────────┘

[ayoisaiah]

@d-Rickyy-b The solution is to use ${1}.

Go uses $name or ${name} to represent capture variables where name is a non-empty sequence of letters, digits, and underscores.

When you use something like $1, it refers to the submatch at index 1. When you use $1_, it tries to find a variable named 1_ that was captured like this (?P<1_>...) which does not exist leading to the empty string.

So if you want to retain the use of indexes ($1) while appending letters, digits, and underscores to the captured variable, you need to use the full syntax: ${1}_:

f2 -f '(.*)\d.txt' -r '${1}_%02d{{ext}}'

┌──────────────────────────────────┐
| ORIGINAL  | RENAMED     | STATUS |
| ******************************** |
| test1.txt | test_01.txt | ok     |
| test2.txt | test_02.txt | ok     |
| test3.txt | test_03.txt | ok     |
└──────────────────────────────────┘

I hope this explains it a bit. You can read the Expand docs to learn more.

I will also update the docs with the next release to mention this behaviour.

[d-Rickyy-b]

Hi @ayoisaiah, thank you very much for the detailed answer, appreciate it!
Your solution works perfectly fine. Looking forward to the updated docs.

Have a great day and keep this project awesome :)

[d-Rickyy-b]

Similarly there seems to be an issue with using capture groups directly in front of index variables.

> f2 -V -f '(.*)\d.txt' -r '$1%02d{{ext}}'
┌───────────────────────────────────────────────────────────┐
| ORIGINAL  | RENAMED      | STATUS                         |
| ********************************************************* |
| test1.txt | test%02d.txt | overwriting newly renamed path |
| test2.txt | test%02d.txt | overwriting newly renamed path |
| test3.txt | test%02d.txt | overwriting newly renamed path |
| test4.txt | test%02d.txt | overwriting newly renamed path |
└───────────────────────────────────────────────────────────┘