Quick Regex Question

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I have a weird value, say, ^%@|CaD5H . What I need to do is make a file with that name. (The program is generating thousands of files. Filenames are one of the values of the data.) Anyways, the Win32 filesystem doesn't like the | as well as other characters. Is there a quick regex (and its reverse) that will convert non /a-zA-Z0-9_-/ to, say, the hex value? (and back again?)

TIA

Comment on Quick Regex Question

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Re: Quick Regex Question by Fastolfe (Vicar) on Feb 08, 2001 at 00:09 UTC
`s/([^\w-])/'%'.unpack("H*", $1)/eg; # %5e%25%40%7cCaD5H` [download] See perlre, pack and unpack. If you need to use another character besides '`%`', go for it.	[reply] [d/l] [select]
Re: Re: Quick Regex Question by Anonymous Monk on Feb 08, 2001 at 00:19 UTC
Thanks. I got it working both ways.. works great. What does the e do? ( .. ("H*", $1)/eg; ) I didn't see it in perlre. tia	[reply]
Re: Re: Re: Quick Regex Question by chipmunk (Parson) on Feb 08, 2001 at 00:32 UTC
It turns out that /e is not documented in perlre because /e does not affect the regular expression. Instead, /e is documented in perlop, in the documentation for s/// (near the bottom).	[reply]
Re: Re: Re: Quick Regex Question by Fastolfe (Vicar) on Feb 08, 2001 at 00:23 UTC
Odd; I can't find it documented either. Its purpose is to tell Perl to evaluate the right-hand-side of a substitution, instead of just using it as-is. This lets you put code in the right-hand-side of a substitution instead of just text.	[reply]
Re: Quick Regex Question by kilinrax (Deacon) on Feb 08, 2001 at 00:11 UTC
Converting to a hex value is pretty easy: `perl -e '$_ = q(^%@\|CaD5H); s/([^\w-])/sprintf qq(%lx), ord($1)/eg; pr +int'` [download] Doing the reverse will be a lot more tricky, unless you add a character to the start of each hex replacement to mark it out as such.	[reply] [d/l]
Re: Re: Quick Regex Question by Albannach (Monsignor) on Feb 08, 2001 at 01:01 UTC
Well if you need to be able to reverse it, why not just convert the whole dang string to hex (like a really conservative version of uuencode), provided the filename won't get too long. -- I'd like to be able to assign to an luser	[reply]