Belazir
asked on
Regex search for "contains X" but "does not contain Y"
This should not be hard!
I have a regex that checks whether the filename passed ends in ".txt". I also want to use regex to check that the filename is NOT "log.txt". My research thus far though seems to indicate that this is insanely hard, or the examples I've found haven't worked (probably me not using them right).
I'm using this in a Perl if statement so I'd appreciate a Noddy full example please...
I have a regex that checks whether the filename passed ends in ".txt". I also want to use regex to check that the filename is NOT "log.txt". My research thus far though seems to indicate that this is insanely hard, or the examples I've found haven't worked (probably me not using them right).
I'm using this in a Perl if statement so I'd appreciate a Noddy full example please...
ddrudik
(?!^log.txt$)\.txt$
ASKER
so
if ((?!^log.txt$)\.txt$) {
...
}
?
if ((?!^log.txt$)\.txt$) {
...
}
?
SOLUTION
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ASKER
well i'll be damned if that only went and worked.
could you talk me through what each bit of that actually means? i like to understand code i'm implementing!!!
could you talk me through what each bit of that actually means? i like to understand code i'm implementing!!!
^ = start of string
(
?! = does not match
log\.txt = literal text "log.txt"
)
.* = any character(except \n) 0 or more times
\.txt = literal text ".txt"
$ = end of string
(
?! = does not match
log\.txt = literal text "log.txt"
)
.* = any character(except \n) 0 or more times
\.txt = literal text ".txt"
$ = end of string
/\A(?!^log\.txt).+\.txt$/ will match 'log.log.txt'' but not 'log.txt.txt'
is that what you want?
is that what you want?
perl -MYAPE::Regex::Explain -e 'print YAPE::Regex::Explain->new(
The regular expression:
(?-imsx:\A(?!^log\.txt).+\
matches as follows:
NODE EXPLANATION
--------------------------
(?-imsx: group, but do not capture (case-sensitive)
(with ^ and $ matching normally) (with . not
matching \n) (matching whitespace and #
normally):
--------------------------
\A the beginning of the string
--------------------------
(?! look ahead to see if there is not:
--------------------------
^ the beginning of the string
--------------------------
log 'log'
--------------------------
\. '.'
--------------------------
txt 'txt'
--------------------------
) end of look-ahead
--------------------------
.+ any character except \n (1 or more times
(matching the most amount possible))
--------------------------
\. '.'
--------------------------
txt 'txt'
--------------------------
$ before an optional \n, and the end of the
string
--------------------------
) end of grouping
--------------------------
The regular expression:
(?-imsx:\A(?!^log\.txt).+\
matches as follows:
NODE EXPLANATION
--------------------------
(?-imsx: group, but do not capture (case-sensitive)
(with ^ and $ matching normally) (with . not
matching \n) (matching whitespace and #
normally):
--------------------------
\A the beginning of the string
--------------------------
(?! look ahead to see if there is not:
--------------------------
^ the beginning of the string
--------------------------
log 'log'
--------------------------
\. '.'
--------------------------
txt 'txt'
--------------------------
) end of look-ahead
--------------------------
.+ any character except \n (1 or more times
(matching the most amount possible))
--------------------------
\. '.'
--------------------------
txt 'txt'
--------------------------
$ before an optional \n, and the end of the
string
--------------------------
) end of grouping
--------------------------
Does it have to be a single regex? How about:
if($name =~ /.txt$/ and $name ne 'log.txt')
#do something
if($name =~ /.txt$/ and $name ne 'log.txt')
#do something
ASKER
what does the A signify?
am i right in thinking that what you've given me should do the txt matching as well as filtering out log.txt? as i've some superfluous code in there if so, i'm still looking for .txt first...
all i care about is that a file called log.txt is ignored - although it would be probably more useful for *log.txt to be ignored rather than log.txt* - can we do that?
am i right in thinking that what you've given me should do the txt matching as well as filtering out log.txt? as i've some superfluous code in there if so, i'm still looking for .txt first...
all i care about is that a file called log.txt is ignored - although it would be probably more useful for *log.txt to be ignored rather than log.txt* - can we do that?
perl -MYAPE::Regex::Explain -e 'print YAPE::Regex::Explain->new(
The regular expression:
(?m-isx:\A(?!^log\.txt).+\
matches as follows:
NODE EXPLANATION
--------------------------
(?m-isx: group, but do not capture (with ^ and $
matching start and end of line) (case-
sensitive) (with . not matching \n)
(matching whitespace and # normally):
--------------------------
\A the beginning of the string
--------------------------
(?! look ahead to see if there is not:
--------------------------
^ the beginning of a "line"
--------------------------
log 'log'
--------------------------
\. '.'
--------------------------
txt 'txt'
--------------------------
) end of look-ahead
--------------------------
.+ any character except \n (1 or more times
(matching the most amount possible))
--------------------------
\. '.'
--------------------------
txt 'txt'
--------------------------
$ before an optional \n, and the end of a
"line"
--------------------------
) end of grouping
--------------------------
The regular expression:
(?m-isx:\A(?!^log\.txt).+\
matches as follows:
NODE EXPLANATION
--------------------------
(?m-isx: group, but do not capture (with ^ and $
matching start and end of line) (case-
sensitive) (with . not matching \n)
(matching whitespace and # normally):
--------------------------
\A the beginning of the string
--------------------------
(?! look ahead to see if there is not:
--------------------------
^ the beginning of a "line"
--------------------------
log 'log'
--------------------------
\. '.'
--------------------------
txt 'txt'
--------------------------
) end of look-ahead
--------------------------
.+ any character except \n (1 or more times
(matching the most amount possible))
--------------------------
\. '.'
--------------------------
txt 'txt'
--------------------------
$ before an optional \n, and the end of a
"line"
--------------------------
) end of grouping
--------------------------
ASKER
Adam - that would probably do it just as well although the variable I have is the file PATH not the file NAME so I can't just do ne.
if( $mystring=~ /^(?!.*log\.txt).*\.txt$/ ){
print "matched.";
}
#will match log.txt.txt but not *log.txt
print "matched.";
}
#will match log.txt.txt but not *log.txt
if( $mystring=~ /^(?!.*log\.txt$).*\.txt$/
print "matched.";
}
#will match log.txt.txt but not *log.txt
print "matched.";
}
#will match log.txt.txt but not *log.txt
why can't you do ne?
#or it may be simpler to write it as
if( $mystring ~=~ /(?<!log).txt$/ ){
print "matched.";
}
if( $mystring ~=~ /(?<!log).txt$/ ){
print "matched.";
}
ASKER CERTIFIED SOLUTION
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ASKER
struggling to keep up with all that... : )
so
/(?<!log)\.txt$/
will match .txt but ignore anything with log in it - right?
so
/(?<!log)\.txt$/
will match .txt but ignore anything with log in it - right?
/(?<!log)\.txt$/
will match .txt but ignore anything that ends in log.txt
If you want to ignore anything with log in it
/^(?!.*log).*\.txt$/
will match .txt but ignore anything that ends in log.txt
If you want to ignore anything with log in it
/^(?!.*log).*\.txt$/
If you want to ignore anything with log in it
/^(?!.*log).*\.txt$/
which means things like slogan.txt or cologne.txt
/^(?!.*log).*\.txt$/
which means things like slogan.txt or cologne.txt
ASKER
okay, that's clear then, thanks
ASKER
damn, that's not working... do I need the ^ in this?
so should
/(?<!log)\.txt$/
be
/^(?<!log)\.txt$/
?
i just ran it and it missed the .txt file it should have picked up
so should
/(?<!log)\.txt$/
be
/^(?<!log)\.txt$/
?
i just ran it and it missed the .txt file it should have picked up
ASKER
sorry, my fault, forget it, i was missing a closing parenthesis
either of them would match '.txt'
with ^ it would match only '.txt'
with ^ it would match only '.txt'
ozo, it seems the pattern:
(?<!log)\.txt$
exclude files such as:
myblog.txt
not sure if that's an issue for Belazir or not.
(?<!log)\.txt$
exclude files such as:
myblog.txt
not sure if that's an issue for Belazir or not.
ASKER
that's what i want, so it filters out oldlog.txt for example
Belazir, ozo's pattern is what you need then, I clearly read your initial question too literally. Thanks for the points and the question.
ASKER
I phrased it too literally by the look of it. Just pleased I got a solution so quickly. Thanks for your help.
Thanks for the generous split. I'm glad I could be a little help in this. It certainly became very active and was a fun question.
bol
p.s. Ozo, thanks for pointing out the oversight in my suggestion. I don't know that I have seen so many posts from you in a single question before. It certainly made this interesting and I'm glad Adam314 posted too. :)
bol
p.s. Ozo, thanks for pointing out the oversight in my suggestion. I don't know that I have seen so many posts from you in a single question before. It certainly made this interesting and I'm glad Adam314 posted too. :)