Pass matched string to command

[mb720]

Hi and thanks for sd!

I was wondering if it's possible with sd to have a command like date create the replacement string, where date gets the matched string as an argument.

I hope I can clarify this with an example.

Assume you have a file that contains dates formatted according to ISO 8601:

Something important happened on 1999-12-31.
On 2019-06-28, I bought ice cream for $3.50.
The previous leap day was on 2020-02-28.

For some reason, all these dates need to be incremented by one day. After running sd, the last sentence should be

The previous leap day was on 2020-02-29.

It's easy to add a day with date:

date -d "2020-02-28 + 1 day" --iso-8601

produces 2020-02-29.

I'd love to use that date command with sd to increment the dates in a file:

sd "\d{4}-\d\d-\d\d" "{date -d "& + 1 day" --iso-8601}" file_with_dates

In this made-up command, I've used & as a backreference to the string matched by the regex \d{4}-\d\d-\d\d, i.e., ISO 8601 dates.

I've used curly braces in the second argument to sd to signify that it's a command whose output sd should use as the replacement string.

Is something like this possible with sd (or sed)?

Does somebody else crave that feature?

[pvinis]

Seems like both sed and sd can do the cmd output thing, but it also seems none of them can handle cmd output and capture groups. :(

[mb720]

@pvinis: When you say the cmd output thing is possible, do you mean sed or sd can do what I described in my original comment? The equivalent of sd "\d{4}-\d\d-\d\d" "{date -d "& + 1 day" --iso-8601}" file_with_dates to increment all dates in the file by one day using the output of date? If so, what's the specific sed/sd command?

[pvinis]

I guess like https://stackoverflow.com/a/17301724/377456. That works for you, right? Using $(date -d ..).

I needed the capture too, so I ended up using perl https://github.com/pvinis/home-dashboard/blob/master/scripts/copy-env-from-1pass#L3.

[mb720]

Thanks, but that doesn't work for me. I'm trying to pass the matched string to date:

sed -E "s/[0-9]{4}-[0-9]{2}-[0-9]{2}/$(date -d "& + 1 day" --iso-8601)/" file_with_dates.txt

Here, the ampersand should be replaced with the matched string (a date in this case). But it's a literal ampersand that gets passed to date.

[pvinis]

I would recommend you use perl too then.

Take this as a base, and go crazy :)

perl -pi -e 's/(.*)/`date -d $2`/ge' file.txt

[balupton]

ripgrep like sd also uses the same rust regex engine https://docs.rs/regex/latest/regex/ perhaps its --only-matching, --replace, --passthru flags could be useful

https://github.com/greymd/teip may also be useful