Why doesn't this perl regex capture the last character?
let $PWD = /Unix_Volume/Users/a开发者_JS百科/b/c/d
I would expect:
echo $PWD | perl -ne 'if( /(\w+)[^\/]/ ){ print $1; }'
to display "Unix_Volume". However, it displays "Unix_Volum." Why doesn't the regex capture the last character?
(\w+) => Unix_Volum
[^\/] => e (not a /)
/ => /
Try:
export PWD=/Unix_Volume/Users/a/b/c/d
perl -MFile::Spec -e'print((File::Spec->splitdir($ENV{_pwd}))[1],"\n")'
You should always use the modules that come with Perl where possible. For a list of them, see perldoc perlmodlib
.
Since \w doesen't have a forward slash in its class, why do you need [^\/] ?
/(\w+)/ will do. It captures the first occurance of this class.
edit: /.*\b(\w+)/ to capture the last occurance.
The (\w+)
group matches and captures the word characters "Unix_Volume" greedily, leaving the position at the / after "Unix_Volume".
The [^\/]
class forces the engine to back up (the greedy +
quantifier gives up characters it's matched to satisfy atoms that follow it) to match a character that is not "/", matching the "e" at the end of "Unix_Volume". Since the matched "e" is outside the capturing group you're left with "Unix_Volum" in $1.
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