4 Feb Peteris Krumins has a new book, Perl One-Liners Explained. His new book is in the same style as his previous books on awk and sed. the gnarly Perl one-liner for accomplishing short tasks that do not need a complete The -e switch allows me to write Perl scripts directly on the command line. Perl One-liners. Perl one-liners are small and awesome Perl programs that fit in a . I explain this example in detail in one-liner (page 41), but basically you.
Perl documentation: Perl one-liners. Perl one-liners Related Examples. Edit file in-place; Execute some Perl code from command line.
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MichaelMoser on Nov 30, if you really need it then finding the one liner you need takes more time than writing it up yourself. I strongly recommend previewing without the -i option before making permanent changes! The one-liners will make heavy use of Perl special variables. It does it by enabling the paragraph slurp mode ond-liners command line argument, which reads the input paragraph-by-paragraph, rather than line-by-line, and prints the paragraphs.
This command line option turns paragraph slurp mode on.
: Perl One Liners
Arguments to one-lineds can alter how Perl processes input. I don’t know a way to make Perl do the same that doesn’t start getting more verbose but there must be a Perl golfer somewhere around here who does …. This basically says – print the line if one-lines doesn’t contain water.
So with Perl, you can do it everywhere. I just bought the first item on your list, PCM, but to myself: I’m lack of this skill, can you give me a suggest in improving this skill. To pipe null delimited data to expained without using xargs -0supply no argument to the -0 option to perl:. You’re correct that -delete is easier in this case, but the perl one liner is handy as a starting point if you’re doing something conditional, or changing file extensions in bulk, etc.
At this moment you are free to do with it whatever you want. To use your example with zsh blobbing: A while loop must be used when making multiple backreferences: It may have limited applicability thou. Perl wxplained regex and the perl regex engine was integrated into other languages until it became a normal language feature.
If matching a single expression, such as words from the paragraphs file, use a for loop to print them all:. I’m new to Perl and was searching for a basic tutorial. The best performance improvement is the transition from the nonworking state to the working state. Perl’s a superset of what can be done with sed, so I tend to use perl for this case even when sed would do, just because I can remember the perl command line args and regex syntax off the top of my head.
If so you can do the following: While it’s not in Perl it uses grep, sed and awkI like this Unix one-liner mine to kill a hanging Firefox process, not so much for the code but for the interesting comment thread that it resulted in on my blog – about Unix processes, zombies, etc. If a recursive replace is needed, either investigate the use of the modules File:: I’ve been doing a lot of regex-based mass manipulation of source code lately and most people write functions across multiple lines.
There are many cases where one-liners are the best way to accomplish a task, particularly text processing. The article will be divided in seven parts or more parts. Construct command lines with -e as the last argument before the expression to avoid these sorts of errors: They have received more thanviews total and they attract a few thousand new visitors every week. I often have to take a trip to the sed man page if I use sed.
Many of one-liners are presented in several different ways so the total number of one-liners in the book is over Selective printing and deleting of lines 7. Also, I think yours would go into an infinite spin if it met a symlink loop say, “ln -s.
Perl One Liners
You don’t even need to have done any real Perl programming to get a lot out of that book, but if you want to learn Perl it will help you as well. Personally, I wouldn’t give Perl one-liners the promotion and attention you are giving perk.
I also like to use perl one liners inside a VI session like this: Alternatives such as cut or awk may be more efficient for explaind delimited data.
Some examples are double spacing a file, numbering the lines, doing various text substitutions, etc. The paragraphs file contains the -0 documentation from perlrunused in the following example:. That said, variations on my one are also handy for doing any further processing on the lines – eg, I oneliners stuff like this pretty regularly: Peter Krumins’ blog about programming, hacking, software reuse, software ideas, computer security, browserling, google and technology. Here we use the binary flip-flop operator.
Article series “Perl One-Liners Explained” – good coders code, great reuse
First let’s start with the “-e” option. Roman, you’re a very sharp guy, always catch all the bugs. I try to avoid Perl when I can not that sed is much better.