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Top Forums UNIX for Dummies Questions & Answers Line deletion help using perl -ne Post 302154905 by lijju.mathew on Wednesday 2nd of January 2008 11:49:35 AM
Old 01-02-2008
Line deletion help using perl -ne

Hi all,

I know the one liner to delete all the lines in a file which matches a pattern
i.e

perl -i.old -ne 'print unless /pattern/' file

Now i need the perl onliner to delete all the lines which doesnt match the pattern. Also what is the difference between perl -i and perl -i.old.
Does perl -i.old archive the existing file?

Your help in this will be appreciated.

Thanks in advance.

Lijju
 

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SVK::Log::Filter::Grep(3)				User Contributed Perl Documentation				 SVK::Log::Filter::Grep(3)

SYNOPSIS
SVK::Log::Filter::Grep - search log messages for a given pattern DESCRIPTION
The Grep filter requires a single Perl pattern (regular expression) as its argument. The pattern is then applied to the svn:log property of each revision it receives. If the pattern matches, the revision is allowed to continue down the pipeline. If the pattern fails to match, the pipeline immediately skips to the next revision. The pattern is applied with the /i modifier (case insensitivity). If you want case-sensitivity or other modifications to the behavior of your pattern, you must use the "(?imsx-imsx)" extended pattern (see "perldoc perlre" for details). For example, to search for log messages that match exactly the characters "foo" you might use svk log --filter "grep (?-i)foo" However, to search for "foo" without regards for case, one might try svk log --filter "grep foo" The result of any capturing parentheses inside the pattern are not available. If demand dictates, the Grep filter could be modified to place the captured value somewhere in the stash for other filters to access. If the pattern contains a pipe character ('|'), it must be escaped by preceding it with a '' character. Otherwise, the portion of the pattern after the pipe character is interpreted as the name of a log filter. STASH
/PROPERTY MODIFICATIONS Grep leaves all properties and the stash intact. perl v5.10.0 2008-08-04 SVK::Log::Filter::Grep(3)
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