Extracting part of a Windows JPG filename and copying into an Exif tag

[mpegleg]

Hello.

Long time no see.  I hope you are all well since I last visited.

Unfortunately I'm a bit rusty in the ol' Regex department. 

I was wondering if someone could please advise me of the modification to this code, to achieve the following:


An example Windows filename: 1963-09-01 [1965-08 S#01] [PIX945034] test1.jpg

This code:

Code Select Expand

-comment<${filename;m/(\[(.+?)\])/;$_=$1}

will result in the comment tag containing [1965-08 S#01] 


I would like to only have everything between the first square brackets like so... 1965-08 S#01

ie. with no square brackets included in the result.


Cheers,
-Paul 

[StarGeek]

Try this
-comment<${filename;m/\[([^]]+)\]/;$_=$1}

The breakdown
Match the first bracket \[
Start a capture group (
Start a character set [
Negate the this character set, in other words, match any character not in this set ^
Close bracket character as part of the set (may or may not need a backslash escape) ] or maybe \]
Close bracket which closes the character set ]
Match one or more of the previous character, which was any character that is not a close bracket +
Close the capture group )
The final matching bracket isn't necessary, but it can be left in if it's easier to read that way.

Example on Regex101

[mpegleg]

Thanks StarGeek. That did the trick. 

.. and thanks also for the excellent breakdown!

[mpegleg]

... and if I wanted to substitute the # for a SPACE character?

ie. 1965-08 S#01

becomes: 1965-08 S 01

[Phil Harvey]

Close bracket character as part of the set (may or may not need a backslash escape) ] or maybe \]

I would definitely use \] here.  But if it works without the \, then I have learned something.

- Phil

[Phil Harvey]

... and if I wanted to substitute the # for a SPACE character?

Try this:

-comment<${filename;m/\[([^\]]+)\]/;$_=$1;tr/#/ /}

- Phil

[mpegleg]

I would definitely use \] here.  But if it works without the \, then I have learned something.

- Phil

Yes, I just tried it both ways, and it does work with or without the \ escape.

Try this:

-comment<${filename;m/\[([^\]]+)\]/;$_=$1;tr/#/ /}

- Phil

Thanks Phil. Perfect 

[mpegleg]

... and finally, while I'm on it... what if I wanted to remove the # so that:

ie. 1965-08 S#01

becomes: 1965-08 S01  <-- ie. the # just gets removed with no space nor character substitution.

[Phil Harvey]

tr/#//d instead of tr/#/ /

[mpegleg]

Excellent. Many Thanks.

[StarGeek]

I would definitely use \] here.  But if it works without the \, then I have learned something.

Yeah, I would tend to add the escape as well but it didn't make it into my notes when I was first researching what characters needed escaping. I wasn't sure if it might have been dependent upon the language involved or not.  It's not a character I use outside of it's regex usage.

[Phil Harvey]

From the Perl documentation:

A ] is normally either the end of a POSIX character class (see POSIX Character Classes below), or it signals the end of the bracketed character class. If you want to include a ] in the set of characters, you must generally escape it.

However, if the ] is the first (or the second if the first character is a caret) character of a bracketed character class, it does not denote the end of the class (as you cannot have an empty class) and is considered part of the set of characters that can be matched without escaping.

Learn something new every day.

- Phil