I'm trying to use Perl's negative look-ahead regular expression
to exclude certain string from targeted string. Please give me your advice.
I was trying to get strings which do not have -sm, -sp, or -sa.
REGEX:
hostname .+-(?!sm|sp|sa).+
INPUT
hostname 9amnbb-rp01c
hostname 9tlsys-eng-vm-r04-ra01c
hostname 9tlsys-eng-vm-r04-sa01c
hostname 9amnbb-sa01
hostname 9amnbb-aaa-sa01c
Expected Output:
hostname 9amnbb-rp01c - SELECTED
hostname 9tlsys-eng-vm-r04-ra01c - SELECTED
hostname 9tlsys-eng-vm-r04-sa01c
hostname 9amnbb-sa01
hostname 9amnbb-aaa-sa01c
However, I got this actual Output below:
hostname 9amnbb-rp01c - SELECTED
hostname 9tlsys-eng-vm-r04-ra01c - SELECTED
hostname 9tlsys-eng-vm-r04-sa01c - SELECTED
hostname 9amnbb-sa01
hostname 9amnbb-aaa-sa01c - SELECTED
Please help me.
p.s.: I used Regex Coach
to visualize my result.
Move the .+- inside of the lookahead:
hostname (?!.+-(?:sm|sp|sa)).+
Rubular: http://www.rubular.com/r/OuSwOLHhEy
Your current expression is not working properly because when the .+- is outside of the lookahead, it can backtrack until the lookahead no longer causes the regex to fail. For example with the string hostname 9amnbb-aaa-sa01c and the regex hostname .+-(?!sm|sp|sa).+, the first .+ would match 9amnbb, the lookahead would see aa as the next two characters and continue, and the second .+ woudl match aaa-sa01c.
An alternative to my current regex would be the following:
hostname .+-(?!sm|sp|sa)[^-]+?$
This would prevent the backtracking because no - can occur after the lookahead, the non-greedy ? is used so that this would work correctly in a multiline global mode.
The following passes your testcases:
hostname [^-]+(-(?!sm|sp|sa)[^-]+)+$
I think it is a little easier to read than F.J.'s answer.
To answer Rudy: the question was posed as an exclusion-of-cases situation. That seems to fit negative lookahead well. :)
Related
this is a regex of a proxy, if I add this to my proxy:
(.*\.|)(abc|google)\.(org|net)
my proxy will not transmit the abc.org, abc.net, google.org, google.net's traffic.
how can I write a regex opposite to this regex? I mean only transmit the abc.org, abc.net, google.org, google.net's traffic.
EDIT-01
My thought is just want to transmit abc.org or www.abc.org, how can I do with that?
Try this:
^(?!(www\.)?(?:abc|google)\.(?:net|org)).*
Demo: https://regex101.com/r/WOnFx8/3/
I used ?! to reverse the matching of your regex. This way, it will match any domain except these specific 4 domains.
Another way to do it is by using this code to include anything before the desired domains:
^(?!(.*\.|)(?:abc|google)\.(?:net|org)).*
demo: https://regex101.com/r/WOnFx8/4/
Your regex you write
(.*\.|)(abc|google)\.(org|net)
mean any string is one of abc.org, gooogle.org, abc.net, google.net, with optional prefix string ends with dot (.)
Like: test.google.org, sub.abc.net,...
I think you want to match string like test.yahoo.com, but not test.google.org. If you can use negative look ahead, this is the answer:
^(.*\.|)(?!(abc|google)\.(org|net))\w+\.\w+$
Explain:
^ and $ to be sure your match is entire url string
Negative look ahead is to check the url is not something like abc.org, abc.net, google.org, google.net
And \w+\.\w+ to check the remain string is kind of URL type (something likes yahoo.com, etc...)
Im going to assume you have lookaheads, if so then you can simply use -
(^.*?\.(?!(abc|google))\w+\.(?:org|net)$)
Demo - https://regex101.com/r/5eC41R/3
What this does is -
Looks for the start of the url (till the first .)
Checks that next part is not abc or google
looks for the next section (till the next .)
Looks for a closing org or net
Note that since it is a lookahead it will be slow compared to other regex matches
I am learning regex and am having trouble getting google from email address
String
first.name#google.com
I just want to get google, not google.com
Regex:
[^#].+(?=\.)
Result: https://regex101.com/r/wA5eX5/1
From my understanding. It ignore # find a string after that until . (dot) using (?=\.)
What did I do wrong?
[^#] means "match one symbol that is not an # sign. That is not what you are looking for - use lookbehind (?<=#) for # and your (?=\.) lookahead for \. to extract server name in the middle:
(?<=#)[^.]+(?=\.)
The middle portion [^.]+ means "one or more non-dot characters".
Demo.
Updated answer:Use a capturing group and keep it simple :)
#(\w+)
Explanation by splitting it up
( capturing group for extraction )
\w stands for word character [A-Za-z0-9_]
+ is a quantifier for one or more occurances of \w
Regex explanation and demo on Regex101
I used the solution's regex for my task, but realized that some of the emails weren't that easy: foo#us.industries.com, foobar#tm.valves.net, andfoo#ge.test.com
To anyone who came here wanting the sub domain as well (or is being cut off by it), here's the regex:
(?<=#)[^.]*.[^.]*(?=\.)
This should be the regex:
(?<=#)[^.]+
(?<=#) - places the search right after the #
[^.]+ - take all the characters that are not dot (stops on dot)
So it extracts google from the email address.
As I was working to get the domain name of email addresses and none corresponded to what I needed:
To not catch subdomains
To match countries top domains (like .com.ar or co.jp)
For example, in test#ext.domain.com.mx I need to match domain.com.mx
So I made this one:
[^.#]*?\.\w{2,}$|[^.#]*?\.com?\.\w{2}$
Here is a link to regex101 to illustrate the regex: https://regex101.com/r/vE8rP9/59
You can get the sumdomain name (without the top-level domain ex: .com or .com.mx) by adding lookaround operators (but it will match twice in test#test.com.mx):
[^.#]*?(?=\.\w{2,}$)|[^.#]*?(?=\.com?\.\w{2}$)
Maybe not strictly a "full regex answer" but more flexible ( in case the part before the # is not "first.last") would be using cut:
cut -d # -f 2 | cut -d . -f 1
The first cut will isolate the part after # and the second one will get what you want.
This will work also for another kinds of email patterns : xxxx#server.com / xxx.yyy.zzz# server.com and so on...
Thanks everyone for your great responses, I took what you had and expanded it with labelled match-groups for easy extraction of separate parts.
Caveat : Regex.Speed = Slow
Another post mentioned how SLOW and nonperformant regexes are, and that is a fair point to remember. My particular need is targeting my own background/slow/reporting processes and therefore it doesn't matter how long it takes.
But it's good to remember whenever possible Regex should NOT be used in any sort of web page load or "needs-to-be-quick" kind of application. In that case you're much better off using substring to algorithmically strip down the inputs and throw away all the junk that I'm optionally matching/allowing/including here.
https://regex101.com/r/ZnU3OC/1
One Regex to rule them all...
Subdomain/Domain/TopLevelDomain/CountryCode extraction for Emails, domain lists, & URLs
Also handles ?Querystring=junk, Slashes/With/Paths, #anchors
Now with more broth, batteries not included
^(?<Email>.*#)?(?<Protocol>\w+:\/\/)?(?<SubDomain>(?:[\w-]{2,63}\.){0,127}?)?(?<DomainWithTLD>(?<Domain>[\w-]{2,63})\.(?<TopLevelDomain>[\w-]{2,63}?)(?:\.(?<CountryCode>[a-z]{2}))?)(?:[:](?<Port>\d+))?(?<Path>(?:[\/]\w*)+)?(?<QString>(?<QSParams>(?:[?&=][\w-]*)+)?(?:[#](?<Anchor>\w*))*)?$
not overly complicated at all... why would you even say that?
Substitution / Outputs
EXAMPLE INPUT: "https://www.stackoverflow.co.uk/path/2?q=mysearch&and=more#stuff"
EXAMPLE OUTPUT:
{
Protocol: "https://"
SubDomain: "www"
DomainWithTLD: "stackoverflow.co.uk"
Domain: "stackoverflow"
TopLevelDomain: "co"
CountryCode: "uk"
Path: "/path/2"
QString: "?q=mysearch&and=more#stuff"
}
Allowed/Compliant Domains : Should ALL MATCH
www.bankofamerica.com
bankofamerica.com.securersite.regexr.com
bankofamerica.co.uk.blahblahblah.secure.com.it
dashes-bad-for-seo.but-technically-still-allowed.not-in-front-or-end
bit.ly
is.gd
foo.biz.pl
google.com.cn
stackoverflow.co.uk
level_three.sub_domain.example.com
www.thelongestdomainnameintheworldandthensomeandthensomemoreandmore.com
https://www.stackoverflow.co.uk?q=mysearch&and=more
foo://5th.4th.3rd.example.com:8042/over/there
foo://subdomain.example.com:8042/over/there?name=ferret#nose
example.com
www.example.com
example.co.uk
trailing-slash.com/
trailing-pound.com#
trailing-question.com?
probably-not-valid.com.cn?&#
probably-not-valid.com.cn/?&#
example.com/page
example.com?key=value
* NOTE: PunyCodes (Unicode in urls) handled just fine with \w ,no extra sauce needed
xn--fsqu00a.xn--0zwm56d.com
xn--diseolatinoamericano-66b.com
Emails : Should ALL MATCH
first.name#google1.co.com
foo#us.industries.com,
foobar#tm.valves.net,
andfoo#ge.test.com
jane.doe#my-bank.no
john.doe#spam.com
jane.ann.doe#sandnes.district.gov
Non-Compliant Domains : Should NOT MATCH
either not long-enough (domain min length 2), or too long (64)
v.gd
thing.y
0123456789012345678901234567890123456789012345678901234567891234.com
its-sixty-four-instead-of-sixty-three!.com
symbols-not-allowed#.com
symbols-not-allowed#.com
symbols-not-allowed$.com
symbols-not-allowed%.com
symbols-not-allowed^.com
symbols-not-allowed&.com
symbols-not-allowed*.com
symbols-not-allowed(.com
symbols-not-allowed).com
symbols-not-allowed+.com
symbols-not-allowed=.com
TBD Not handled:
* dashes as start or ending is disallowed (dropped from Regex for readability)
-junk-.com
* is underscore allowed? i donno... (but it simplifies the regex using \w instead of [a-zA-Z0-9\-] everywhere)
symbols-not-allowed_.com
* special case localhost?
.localhost
also see:
Domain Name Rules :: Super handy ASCII Diagram of a URL
see: https://stackoverflow.com/a/66660651/738895 *
Side NOTE: lazy load '?' for subdomains{0,127}? currently needed for any of the cases with country codes... (example: stackoverflow.co.uk)
Matches these, but does NOT grab $NLevelSubdomains in a match group, can only grab 3rd level only.
This is a relatively simple regex, and it grabs everything between the # and the final domain extension (e.g. .com, .org). It allows domain names that are made up of non-word characters, which exist in real-world data.
>>> regex = re.compile(r"^.+#(.+)\.[\w]+$")
>>> regex.findall('jane.doe#my-bank.no')
['my-bank']
>>> regex.findall('john.doe#spam.com')
['spam']
>>> regex.findall('jane.ann.doe#sandnes.district.gov')
['sandnes.district']
I used this regular expression to get the complete domain name '.*#+(.*)' where .* will ignore all the character before # (by #+) and start extracting cpmlete domain name by mentioning paranthesis and complete string inside(except linebrake characters)
I'm struggling with forming a regex that would match:
Just domain in case of URL
Whole string in case of no URL
Acceptance test (regex should match bold text):
http://mozart.co.uk
https://avocado.si/hmm
http://www.qwe123qwe.com
Starbucks
Benchmark 123
So far I've come up with this:
([^\/\/]+)(?:,|$)
It works fine, but not for URLs with trailing slash on the end. How can I modify the expression to include full path (everything on the right side of http(s)://) as well? Thank you.
This regex will match them if it starts with http:// or https:// until the next slash. If it doesn't start with http:// nor https:// then it will match the whole string. Close enough?
(?:^https?:\/\/([^\/]+)(?:[\/,]|$)|^(.*)$)
I should note that most languages have functions built in to properly parse URLs and these are preferable.
You should note that I've got 2 sets of capturing parentheses, so depending on your language that may be significant.
Maybe that ^(http[s]?:\/\/)?(.*)$. Play here: https://regex101.com/r/iZ2vL4/1
This will have Matching groups, the domain you want will be in the 4th matching group.
/^((http[s]?|ftp):\/\/)?\/?([^\/\.]+\.)*?([^\/\.]+\.[^:\/\s\.]{1,3}(\.[^:\/\s\.]{1,2})?(:\d+)?)($|\/)([^#?\s]+)?(.*?)?(#[\w\-]+)?$/mg
Regex101.com workbench to check out your URLs just paste them in the "TEST STRING" Textbox to test it out.
Don't recall where I got this... so I don't know who to credit. But it's pretty slick!
I need to allow an IP/DNS name from a text box. I am looking for a IP regular expression which work for IP.
Now I am using one regular expression:
/\b(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b/
which was working for 0-255 range. But allowing invalid IP such as : 121.21.05.234.01 which has 5 parts.
I need a regular expression which will work in all scenario's like below:
10.2.22.1 - true
123.123.123.123 - true
123.123.023.12 - true
12.23.12.0 - true
121.21.05.234.01 - false
Please provide me DNS expression also.
Try to anchor your regex with ^ and $, which will make it match the whole string.
Are you looking for a way to specify an occurrence count?
You may achieve this with curly brackets.
An exemple here.
In your case, it would lead to:
/\b(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3}\b/
(I added a \ to escape the dot, too)
i've searched all over the net for this but does anyone have a Regular expression to extract the host from this text?
Host: my.domain.com
check if this helps you
function fnGetDomain(url)
{
return (url.match(/:\/\/(.[^/]+)/)[1]).replace('www.','');
}
(([a-zA-Z0-9\-]+\.)+[a-zA-Z0-9\-]+$)
With capturing group (you have to retrieve the value from group 1 afterwards):
Host:\s*(.*)$
With lookbehind (doesn't work in most regex engines due to variable-length lookbehind, but the match itself is the value you want):
(?<=Host:\s*).*$