$find='\\d{2}-\\d{2}-\\d{4}'
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\d{2}-\d{2}-\d{4}
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perl -pi.bak -e "s|d{2}-d{2}-d{4}|...|g" ...
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Why don't you use

my $find    = '\\d{2}-\\d{2}-\\d{4}';
my $replace = '{date}';

s/$find/$replace/
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Update: If I were to speculate:

To which you'll reply "So I can use $1"

To which I'll reply. Well, you could use

my $find    = '(\\d{2}-\\d{2})-(\\d{4})';
my $replace = '$2-$1';

eval "s/\$find/$replace/"
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but that would be pretty dumb. You need a template system, and the Perl interpreter is not that. The one I've come across that best fits the current syntax is String::Interpolate.

Are you running this in a shell script? Are you running this in a Python or Ruby or ?? program?

The backquotes and the double quotes mean that your perl code is first interpolated by the shell and then interpolated by perl.

You probably want something like this instead (UNTESTED):

my $find    = qr/\d{2}-\d{2}-\d{4}/;
my $replace = 'something else';

{   local ( $^I, @ARGV ) = ( '.bak', $_ );
    while ( <> ) {
        s|$find|$replace|g;
        print;
        }
    }
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If you're indeed using `perl -e ...` from inside perl, you need to add an extra layer of backslashes, as you're forgetting to protect against the extra interpolation due to the shell: you're running perl, invoking the shell (``) which in turn invokes perl. And your variables, esp. $_ hopefully is something very simple that parses as a single shell word.

Either way, do consider using single quotes instead of your double quote: `perl -e '...'`, which allows you to get rid of some backslashes...

jakobi:

I'd suggest this edit:

s/add an extra.*/be whacked with a cluestick!/
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</snarky_mode>

...roboticus

But your regex contains .* and this results in just the four letter word RTFM, which I hate with a passion in its standalone version.

Shouldn't we all remember that RTFM is a protocol prefix and requires an obligatorie MEME URI which provides at least an additional hint or keyword?

So the proper use should be a still sufficiently terse RTFM://<check_both_quoting_and_consider_rethinking_your_approach>.

;>
Peter (who is a bit ashamed to have failed roboticus' elegance & brevity test)