Perl-regex: Difference between revisions
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#REDIRECT [[Regular_expressions_with_Perl]] |
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__NOTOC__ |
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= Perl Regex = |
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== How to search and replace a word or phrase == |
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* '''All matches''' |
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<pre><nowiki> |
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perl -pi -e 's/old string/new string/g' /path/to/the/file |
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</nowiki></pre> |
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This command line replaces all the instances of ''old string'' with ''new string'' that are found in `/path/to/the/file`. To replace only the first instance, remove the ''g ''at the end of the command. |
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* '''Conditional match''' |
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<pre><nowiki> |
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perl -pi -e 's/old string/new string/ if m/my unique string/' /path/to/the/file |
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</nowiki></pre> |
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This command line search only for the lines that matches ''my unique string'' and then replaces ''old string'' with ''new string'' |
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* '''Search and replace using bash shell variables''' |
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<pre><nowiki> |
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sed -i -e s%old string%$BASH_VARIABLE% /path/to/the/file |
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</nowiki></pre> |
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In order to get this done is convenient to use `sed` instead `perl` command. |
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Always use `-i -e` instead `-ie`, if not you will end up with another file with the same name but with an `e` at the end of the file name. |
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== How to remove/replace a whole line == |
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* '''Conditional match''' |
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<pre><nowiki> |
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perl -pi -e '$_="" if m/my unique string/' /path/to/the/file |
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</nowiki></pre> |
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This command line removes all the lines that matches ''my unique string'' |
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== How to work with "sed" command == |
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Attached is a file [[[Media:perl-regex$sed1line.txt]]] with a very useful list of sed commands called ''One-Liners for sed''. Updated version is always available at http://sed.sourceforge.net/sed1line.txt |
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Latest revision as of 23:55, 6 June 2015
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