Replace quotes within quote encapsulated string using Perl regular expressions

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I am trying to replace quotes within a pipe delimited and quote encapsulated file without replacing the quotes providing the encapsulation.

I have tried using the below Perl line to replace the quotes with a back tick ` but am not sure how to replace only the quotes and not the entire group 1.

Sample data (test.txt):

"2"|""Text in quotes""|"ab"\n
"3"|"Text "around" quotes"|"abc"\n

perl -pi.bak -e 's/(?<=\|")(.*)(?="\|)/\1`/' test.txt

Here is what is happening:


Here is what I am trying to achieve:

"2"|"`Text in quotes`"|"ab"\n
"3"|"Text `around` quotes"|"abc"\n

Regex for Quoted String with escapable quotes, One of the common patterns in that space is the quoted-string, which is a allow people to escape their quotes like this: "some \"value\" is safe". the Regex engine that a string should end with the same quote character that  Replace double quotes with a single quote within a double quoted string Hi Froum. I have tried in vain to find a solution for this problem - I'm trying to replace any double quotes within a quoted string with a single quote, leaving everything else as is.

quotemeta, This is the internal function implementing the \Q escape in double-quoted strings. \E ) are useful when interpolating strings into regular expressions, because by Starting in Perl v5.16, Perl adopted a Unicode-defined strategy for quoting of a use feature 'unicode_strings' , which is to quote all characters in the upper  PRXMATCH(/regular-expression/, source) Ex. prxmatch('/world/', 'Hello world!'); The above example uses the PRXMATCH function to find the position (=7) of the search-string (world) in the source-string (Hello World) Find and Replace using PRXCHANGE: PRXCHANGE is not only used to find strings but also to replace it using specified rules.

Perl uses $1 as the placeholder for the first capturing group in the replacement part of the regex instead of \1 (used in the matching part of the regex). Your regex wasn't matching the inner quotes and would fail to match the first or last field of your pipe delimited data. Your substitution also failed to include a quote character before the captured group.


perl -pi.bak -e 's/(?<=(?:^|\|)")"([^"]*)"(?="(?:$|\|))/`$1´/' test.txt

Strings · Learn Julia the Hard Way, A string literal is surrounded by double quotes: " string " . Within the string, you can escape a double-quote using a backslash: + Regular expressions (​regexes) are special strings that represent particular patterns. As such, it encapsulates (to use a little more OOP terminology than one would normally be allowed to in a  Get text between quotes. Comments. Post Posting Guidelines Formatting - Now. Top Regular Expressions. Strip non-digits Railcar Number start / end of the string \b

Another Perl. After splitting by array @F, check for " that is not at the beginning/end of the elements.

 perl -F"\|"  -lane   ' for(@F) { s/(?<!^)"(?!$)/`/g }; print join("|",@F) ' 

with the given inputs

$ cat grasshopper.txt
"2"|""Text in quotes""|"ab"
"3"|"Text "around" quotes"|"abc"
$  perl -F"\|"  -lane   ' for(@F) { s/(?<!^)"(?!$)/`/g }; print join("|",@F) ' grasshopper.txt
"2"|"`Text in quotes`"|"ab"
"3"|"Text `around` quotes"|"abc"

Double Quotes and Regular Expressions, Double quotes around a string are used to specify a regular expression search using the Perl-compatible regular expressions library written by Philip Hazel). a T. As with a string, a regular expression in a numeric context gets converted to  Double Quotes and Regular Expressions Double quotes around a string are used to specify a regular expression search (compatible with Perl 5.005, using the Perl-compatible regular expressions library written by Philip Hazel). If you don't know how to use them, try consulting the man pages for ed, egrep, vi, or regex. If not, read the Perl docs

Strings - Manual, The simplest way to specify a string is to enclose it in single quotes (the character '). To specify a literal single quote, escape it with a backslash (\). and the Perl-​compatible regular expression functions for advanced find & replace functionality. runs of the test, and this was always the fastest variable encapsulation style) A regular expression is a string of characters that defines the pattern or patterns you are viewing. The syntax of regular expressions in Perl is very similar to what you will find within other regular expression.supporting programs, such as sed, grep, and awk.

Sed regex quotation mark, Note that on Windows you will need the double quotation marks (") here. and in the replacement part of the s command (see Regular Expression Addresses In terms of regular expressions, a basic quoted string literal is given as: Alas, neither of those cases encapsulate the whole string in a single type of quote mark​. Also within the string (inside the outer double quotes) I may have other double quotes that need to be preserved and not modified. I'm not sure if this is something that can be accomplished using expressions, and if so what are the necessary search and replace strings. Thanks in advance.

perlop - Perl operators and precedence, They include variables, quote and quote-like operators, any expression in parentheses If, however, the variable has been used in only string contexts since it was set, and has a Binary "=~" binds a scalar expression to a pattern match. While we usually think of quotes as literal values, in Perl they function as operators,  Strings can be placed either between single quotes ' or double quotes " and they have slightly different behavior.. Single quoted strings. If you put characters between single quotes ', then almost all the characters, except the single-quote itself ', are interpreted as they are written in the code.

  • I'm surprised you don't want "3"|"Text ""around"" quotes"|"abc"\n (proper CSV for 3, Text "around" quotes and abc) instead of clobbering your text.
  • You didn't define how to handle text that contains `
  • Grasshopper, once you are back, please let us know how you want to represent literal backticks in your fields. In short, if you have "2"|""Text `in` quotes""|"ab", what should it look like? Should in be enclosed with a double backticks? Or escaped with a backslash? Or any other way?
  • @ikegami I am loading this data into a database using SQL*Loader and was fearful that text such as ""around"" would break the load. If it works this would be preferrable.
  • @WiktorStribiżew and @ikegami literal backticks in the fields should be enclosed in `` double backticks.
  • Note that split and multiple regexes don't necessarily lose efficiency when compared to a more complicated single regex. If you really care, you should benchmark them.
  • @Grinnz Corrrect! At first I had "may lose" ... but then, in this case, against a well written regex, it should lose "some" I think. Indeed, should benchmark. ... actually, I put back that "may". thanks
  • Split could match a pipe contained within a quote encapsulated string.
  • @robartsd Well ... there are various possibilities with data that would torpedo any processing. In this problem a pipe can't be where it shouldn't be, or we should consider the separator to be "|" -- and this is possible as well (and could be the pattern for the separator in split). It depends on what real data is like and the OP may need refinements to any approach we offer.
  • @ikegami heh, no decision but just picked up theirs. It does need a good mention, thank you. Edited
  • You should mention how you decided to handle text that already contains `.
  • @ikegami There is no way to add that to the answer since OP has not provided any specs regarding how to represent literal backticks inside the fields (escaped with another backtick? A backslash?). It can be easily fixed once the specs are revealed.
  • That's my point. You made an assumption but didn't document it. What did you assume the OP's spec says concerning this?
  • @ikegami Now, it works as expected. Literal backticks must be doubled.