OneAndOneIs2

I need a "Notes to self" category for these posts... But then I'd have to go back through over a thousand posts to add the tag..

I seem to need to rename batches of files quite a lot these days. The command-line isn't always the best way to do this when it's complicated stuff, so I found a helpful bit of software to use - it lets you see what the currently-defined operation would do to the files before it does it.

For simple stuff, like cropping a few characters out of the same file, no explanation is needed. But regexp things can be trickier, as ever. The tricky bit was in working out how to call text from wild-carded searches.

So if you have, say:

XXXfile1.jpg
fileXXX2.jpg
file3XXX.jpg

and you want to remove the 'XXX' from all three, the search .*XXX.* will work, but is useless because it only has one element. You need it to be THREE elements: The bit before XXX, the bit after XXX, and the XXX itself.

So you need to use (.*)(XXX)(.*) as the search term

And then use \1\3 as the replace term, to tell it to use everything before and after the XXX, but not the XXX itself.

Very simple and fairly standard in principle, but every damn language seems to have its own way of referring to elements - no brackets needed, different brackets needed, no period before the wildcard, use %1 or \1 or $1 to refer to the first element... the principle may always be the same but the phrasing of it varies enormously.

Hence the need to write this little reminder...