Differences between version 21 and predecessor to the previous major change of PerlOneLiners.
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| Newer page: | version 21 | Last edited on Wednesday, June 9, 2004 8:46:30 pm | by JohnMcPherson | Revert |
| Older page: | version 19 | Last edited on Friday, April 9, 2004 11:37:38 am | by AristotlePagaltzis | Revert |
@@ -1,7 +1,15 @@
Many oneliners rely on the magic of [Perl]'s __-i__ switch, which means when files supplied on the commandline are opened they are edited in place, and if an extension was passed, a backup copy with that extension will be made. __-e__ specifies the [Perl] code to run. See perlrun(1) for any other switches used here - in particular, __-n__ and __-p__ make powerful allies for __-i__.
The unsurpassed power of [Perl]'s RegularExpression flavour contributes a great deal to the usefulness of nearly every oneliner, so you will also want to read the perlretut(1) and perlre(1) manpages to learn about it.
+
+!! Perl pie
+
+ perl -pi -e 's/foo/bar/' file
+
+Does an inplace sed on the file. [GNU] sed(1) v4 also supports this with -i. The advantage of using perl instead
+of sed is for use of perl's RegularExpressions if you are more familiar with them than the [POSIX] ones used by sed.
+(If you only need a simple query and replacement, sed will probably be quicker).
!! Removing empty lines from a file
perl -ni.bak -e'/\S/ && print' file1 file2
