Perl: replace binary content

Question

I need to replace a binary content with some other content (textual or binary) in Perl.

If the content is textual I can use s/// to replace content.

 my $txt = "tomturbo";
 $txt =~ s/t/T/g;      # TomTurbo

But that is not working if the content is binary.

Is there an easy way to handle that??

Thanks!

If you mean that you read from a "binary" file (under :raw), then you'll need to unpack what you read before regex can work with it. (I don't know whether you consider that "easy" or not :) — zdim
– zdim, Commented Mar 15, 2018 at 19:52
The above comment stands corrected by ikegami answer. I'm leaving it for now since that may well be what you want to do, for convenience. — zdim
– zdim, Commented Mar 15, 2018 at 20:10

ikegami · Accepted Answer · 2018-03-15 20:06:08Z

5

Perl's regex engine will work with arbitrary strings.

s/t/T/g

is no different than

s/\x{74}/\x{54}/g

meaning it will change the value of characters from 74₁₆ to 54₁₆. The regex engine doesn't care whether value 74₁₆ means t or something else.

In binary data, character A₁₆ doesn't indicate the end of a line, so you'll want to use the s flag, avoid the m flag, and avoid using $.

Furthermore, you'll find the i flag and the built-in character class (e.g. \d, \p{Letter}, etc) useless unless you are matching against strings of decoded text (strings of Unicode Code Points), but you may otherwise use any feature of the regex engine.

edited Mar 15, 2018 at 20:06

answered Mar 15, 2018 at 20:01

ikegami

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3 Comments

chris01 Over a year ago

That works only for single characters I think. I need it for whole strings that are in a scalar (e.g. s/$binval/$newval/)

ikegami Over a year ago

No. Perl's regex engine will work with arbitrary strings. But that doesn't excuse the need to form a proper regex (s/\Q$binval\E/$newval/).

chris01 Over a year ago

WOW! That is a real easy way!

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