Strip a dot and some digits from the end of a string:

my $str = '02/17/2003 11:44:19.123';
$str =~ s/\.\d+$//;
print "$str\n";
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We could *try* to say s/.\d+$// but it happens that the dot is magic (matches most anything). So to match a dot we have to "escape" it with the backslash. Like this: \.

Next comes \d which means "any digit". The plus after it means "one or more". Like this: \d+

Then we have the $   When $ is used at the end of a regex, it means "anchor this match to the end of the string" (there are some nuances here we won't bother with). Actually, in this case we don't need the $ anchor -- we know that there is only one place in the string that will match "a dot followed by some digits". But it is perhaps a kindness to the next human who looks at the code to provide this visual clue that the match is expected to occur at the end of the string. So now we have: \.\d+$

We put this regex snippet into a substitution regex: s/ / / But we leave the second half empty. This means "whatever you matched in the first half of the s///, replace it with nothing at all".

So reading s/\.\d+$// straight off the page, we could translate it as: match a literal dot followed by some digits anchored to the end of the string and replace them with nothing.

Hope that helps.

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"Perl is a mess and that's good because the
problem space is also a mess." - Larry Wall