I need to write a regex to allow the contents but block the special characters ' and -- in the string. I am working on a product which uses the regex to allow or block contents goofing around the product, I managed to find the below pattern:
^('|--|#|\\x27|\\x23)$
Which is supposed to match --, ' and # in the string, but when I tested this pattern in some online regex pattern matching. it was not highlighting the string when it contains --, ' or #.
See Start of String and End of String Anchors at regular-expressions.info:
The caret ^ matches the position before the first character in the string. Applying ^a to abc matches a. ^b does not match abc at all, because the b cannot be matched right after the start of the string, matched by ^.
Similarly, $ matches right after the last character in the string. c$ matches c in abc, while a$ does not match at all.
Also, \x27 matches a ', and \x23 matches a #, thus, no need doubling them with literals.
So, you just need
(--|\x27|\x23)
Or (using a non-capturing group):
(?:--|\x27|\x23)
See demo
Related
I am trying to match the below string with Regular expression
string : PKGx.1234 ... BBA
Regular expression : ^\bPKG[0-9]{0,1}.[0-9]{0,4}\ ...\ \bBB[A-B]{1}?$
but i am getting no match error
can anyone help me with how can i remodify the regular expression to match the given string ..?
You have a character x after PKG that the pattern tries to match with an optional digit [0-9]? If there should be an optional single a lowercase character, you can use [a-z]? instead.
You can omit the word boundary before the BB as there is an implicit word boundary in between.
Note that you don't have escape the spaces, but you do have to escape the dot to match it literally.
^PKG[a-z]?\.[0-9]{0,4} \.{3} BB[A-B]\b
Regex demo
If you want to match the whole string including the space and comma at the end, including using the $ anchor to assert the end of the string:
^PKG[a-z]?\.[0-9]{0,4} \.{3} BB[A-B] , *$
Regex demo
I have a function, translate(), takes multiple parameters. The first param is the only required and is a string, that I always wrap in single quotes, like this:
translate('hello world');
The other params are optional, but could be included like this:
translate('hello world', true, 1, 'foobar', 'etc');
And the string itself could contain escaped single quotes, like this:
translate('hello\'s world');
To the point, I now want to search through all code files for all instances of this function call, and extract just the string. To do so I've come up with the following grep, which returns everything between translate(' and either ') or ',. Almost perfect:
grep -RoPh "(?<=translate\(').*?(?='\)|'\,)" .
The problem with this though, is that if the call is something like this:
translate('hello \'world\', you\'re great!');
My grep would only return this:
hello \'world\
So I'm looking to modify this so that the part that currently looks for ') or ', instead looks for the first occurrence of ' that hasn't been escaped, i.e. doesn't immediately follow a \
Hopefully I'm making sense. Any suggestions please?
You can use this grep with PCRE regex:
grep -RoPh "\btranslate\(\s*\K'(?:[^'\\\\]*)(?:\\\\.[^'\\\\]*)*'" .
Here is a regex demo
RegEx Breakup:
\b # word boundary
translate # match literal translate
\( # match a (
\s* # match 0 or more whitespace
\K # reset the matched information
' # match starting single quote
(?: # start non-capturing group
[^'\\\\]* # match 0 or more chars that are not a backslash or single quote
) # end non-capturing group
(?: # start non-capturing group
\\\\. # match a backslash followed by char that is "escaped"
[^'\\\\]* # match 0 or more chars that are not a backslash or single quote
)* # end non-capturing group
' # match ending single quote
Here is a version without \K using look-arounds:
grep -oPhR "(?<=\btranslate\(')(?:[^'\\\\]*)(?:\\\\.[^'\\\\]*)*(?=')" .
RegEx Demo 2
I think the problem is the .*? part: the ? makes it a non-greedy pattern, meaning it'll take the shortest string that matches the pattern. In effect, you're saying, "give me the shortest string that's followed by quote+close-paren or quote+comma". In your example, "world\" is followed by a single quote and a comma, so it matches your pattern.
In these cases, I like to use something like the following reasoning:
A string is a quote, zero or more characters, and a quote: '.*'
A character is anything that isn't a quote (because a quote terminates the string): '[^']*'
Except that you can put a quote in a string by escaping it with a backslash, so a character is either "backslash followed by a quote" or, failing that, "not a quote": '(\\'|[^'])*'
Put it all together and you get
grep -RoPh "(?<=translate\(')(\\'|[^'])*(?='\)|'\,)" .
I am using Notepad++ to remove some unwanted strings from the end of a pattern and this for the life of me has got me.
I have the following sets of strings:
myApp.ComboPlaceHolderLabel,
myApp.GridTitleLabel);
myApp.SummaryLabel + '</b></div>');
myApp.NoneLabel + ')') + '</label></div>';
I would like to leave just myApp.[variable] and get rid of, e.g. ,, );, + '...', etc.
Using Notepad++, I can match the strings themselves using ^myApp.[a-zA-Z0-9].*?\b (it's a bit messy, but it works for what I need).
But in reality, I need negate that regex, to match everything at the end, so I can replace it with a blank.
You don't need to go for negation. Just put your regex within capturing groups and add an extra .*$ at the last. $ matches the end of a line. All the matched characters(whole line) are replaced by the characters which are present inside the first captured group. .
matches any character, so you need to escape the dot to match a literal dot.
^(myApp\.[a-zA-Z0-9].*?\b).*$
Replacement string:
\1
DEMO
OR
Match only the following characters and then replace it with an empty string.
\b[,); +]+.*$
DEMO
I think this works equally as well:
^(myApp.\w+).*$
Replacement string:
\1
From difference between \w and \b regular expression meta characters:
\w stands for "word character", usually [A-Za-z0-9_]. Notice the inclusion of the underscore and digits.
(^.*?\.[a-zA-Z]+)(.*)$
Use this.Replace by
$1
See demo.
http://regex101.com/r/lU7jH1/5
I want to find all instance of word (say myword), with the added condition that the word has whitespace, "#", "#" afterwords, or is the end of input.
Input string:
"myword# myword mywordrick myword# myword"
I want the regex to match everything besides mywordtrick -
myword#
myword
myword#
myword
I am able to match against the first 3 with myword[##\s]
I thought myword[##\s\z] would match against all 4, but I only get 3
I try myword[\z] and get no matches
I try myword\z and get 1 match.
I figure \z inside a [] doesn't work, because [] is character based logic, rather than position based logic.
Is there a way to use a single regex to match the expressions I am interested in? I do not want to use both myword[##\s] and myword\z unless I really have to.
Your regex would be,
myword(?:[##\s]|$)
It matches the string myword along with the symbols only if it's followed by # or # or \s or $. $ means the end of the line.
DEMO
I have regular expression:
BEGIN\s+\[([\s\S]*?)END\s+ID=(.*)\]
which select multiline text and ID from text below. I would like to select only IDs with prefix X_, but if I change ID=(.*) to ID=(X_.*) begin is selected from second pair not from third as I need. Could someone help me to get correct expression please?
text example:
BEGIN [
text a
END ID=X_1]
BEGIN [
text b
text c
END ID=Y_1]
text aaa
text bbb
BEGIN [
text d
text e
END ID=X_2]
text xxx
BEGIN [
text bbb
END ID=X_3]
It isn't the .* that's gobbling everything up as people keep saying, it's the [\s\S]*?. .* can't do it because (as the OP said) the dot doesn't match newlines.
When the END\s+ID=(X_.*)\] part of your regex fails to match the last line of the second block, you're expecting it to abandon that block and start over with the third one. That's what it have to do to make the shortest match.
In reality, it backtracks to the beginning of the line and lets [\s\S]*? consume it instead. And it keeps on consuming until it finds a place where END\s+ID=(X_.*)\] can match, which happens to be the last line of the third block.
The following regex avoids that problem by matching line by line, checking each one to see if it starts with END. This effectively confines the match to one block at a time.
(?m)^BEGIN\s+\[[\r\n]+((?:(?!END).*[\r\n]+)*)END\s+ID=(X_.*)\]
Note that I used ^ to anchor each match to the beginning of a line, so I used (?m) to turn on multiline mode. But I did not--and you should not--turn on single-line/DOTALL mode.
Assuming there aren't any newlines inside a block and the BEGIN/END statements are the first non-space of their line, I'd write the regex like this (Perl notation; change the delimiters and remove comments, whitespaces and the /x modifier if you use a different engine)
m{
\n \s* BEGIN \s+ \[ # match the beginning
( (?!\n\s*\n) .)*? # match anything that isn't an empty line
# checking with a negative look-ahead (?!PATTERN)
\n \s* END \s+ ID=X_[^\]]* \] # the ID may not contain "]"
}sx # /x: use extended syntax, /s: "." matches newlines
If the content may be anything, it might be best to create a list of all blocks, and then grep through them. This regex matches any block:
m{ (
BEGIN \s+ \[
.*? # non-greedy matching is important here
END \s+ ID=[^\]]* \] # greedy matching is safe here
) }xs
(add newlines if wanted)
Then only keep those matches that match this regex:
/ID = X_[^\]]* \] $/x # anchor at end of line
If we don't do this, backtracking may prevent a correct match ([\s\S]*? can contain END ID=X_). Your regex would put anything inside the blocks until it sees a X_.*.
So using BEGIN\s+\[([/s/S]*?)END\s+ID=(.*?)\] — note the extra question mark — one match would be:
BEGIN [
text b
text c
END ID=Y_1]
text aaa
text bbb
BEGIN [
text d
text e
END ID=X_2]
…instead of failing at the Y_. A greedy match (your unchanged regex) should result in the whole file being matched: Your (.*) eats up all characters (until the end of file) and then goes back until it finds a ].
EDIT:
Should you be using perls regex engine, we can use the (*FAIL) verb:
/BEGIN\s+\[(.*?)END\s+ID=(X_[^\]]*|(*FAIL))\]/s
"Either have an ID starting with X_ or the match fails". However, this does not solve the problem with END ID=X_1]-like statements inside your data.
Change your .* to a [^\]]* (i.e. match non-]s), so that your matches can't spill over past an END block, giving you something like BEGIN\s+\[([^\]]*?)END\s+ID=(X_[^\]]*)\]