Ruby One-Liners
benoithamelin.tumblr.com
benoithamelin.tumblr.com
The command line switches are the same, the BEGIN/END block stuff is the same, the $F auto-splitting is the same.
Good on Ruby, that's the stuff that makes Perl one-liners actually worth coming back to again and again.
$ cat data.rb
DATA.each_line { |ln|puts ln }
__END__
fish
cat
dog
$ ruby data.rb
fish
cat
dogThis is very useful to script a setup -> for reach line -> summary of a file e.g. initialise a map in BEGIN, fill the map for each line, and print the map in END.
I use Ruby for text processing now, because it's easier to read than Perl, but I loop on stdin with IO.readlines, each and split. It could be less efficient but I'm not parsing billions of records. I value readability more than one liners.
That's fair. That kind of Perl is also very different than the kind of Perl you would use to write Mojolicious applications, or system utils, or daemons. Those features are very specifically for quick one-liners[1], and in some cases don't even make sense outside of that.
> I use Ruby for text processing now, because it's easier to read than Perl, but I loop on stdin with IO.readlines, each and split.
In a one-liner, or as a small source file? Doing that in a small source file is also common in Perl, but if you're doing that as a one-liner, I think you're not making it more readable, you're making it less so, as the executable/language specifically support features to make that easier to do which you're ignoring, obfuscating the important parts of the code with verbose obvious bits. It's sort of like making sure to spell out et cetera instead of using etc even when texting or using Twitter.
1: BEGIN actually has some important uses in Perl, but under the covers for most people, so they never have to deal with it.
For a really simple case, leveraging a module in the language to do the heavy lifting and do something per line. If I want robust CSV conversion for a TSV, loading up a CSV module in Perl or Ruby and letting it act on each line (after appropriately split on tab, and with the newline removed from each line, both a single command line switch away) is a very small one liner that's appropriately leveraging the language to do something that's hard with common shell utils.
There's a whole world of ways to leverage a powerful ecosystem with the built in one-liner features of Perl and Ruby. If you don't often find yourself doing a lot in the shell, then I can understand having a hard time imagining a case where it's not always better for a small source file, but for anyone whose responsibilities also entail a fair amount of system administration tasks, it can be extremely helpful.
If for nothing else, the number of times I've used autosplit or a nice regex to parse a complex line into an appropriate SQL statement I can output to another file, check, and then run is quite large. These often amount to a single regex and print per line, and are on some other log portion I've already grepped out, so generating the boilerplate for the line looping is actually more code than the actual statements that need to run. Add to that the times that there's no maintenance needed because the scripts are used to fix a one-off problem, and there are specific use cases where one-liners make sense. For a lot of people's workload, that might not be the case, but I definitely see the cases where it is.
The removal of the flip-flop operator, which is a fundamental tool in text processing, sent a very clear signal about the Ruby direction (that is, to be "The Rails language" and nothing else).
How can one be sure now, that all the functionality you've mentioned (and more) won't be removed as well?
Perl can be ugly, but its foundation in text processing are established.
Well that never happened. It was deprecated with the intention to remove it, but they backtracked: https://bugs.ruby-lang.org/issues/5400#note-25
$/ input record separator (default argument for "gets")
$\ output record separator ("print" prints it at last)
$, default separator for Array#join and print
$; default separator for String#split
Ruby (and Perl) can and probably should be used for many tasks where you might use awk and sed and don't particularly care about performance.
An argument "against readability" is culture. For sysadmins, Perl is a well-known language; it's not unreadable¹. Note that the same applies to Bash, and Bash scripts are still popular. This doesn't imply that Perl/Bash scripts should be universally used, but that within a certain culture, they make perfect sense.
¹=when talking about oneliners
There's plenty of stuff that is similar to Perl, which in turn had borrowed from awk, sed and other tools. The biggest difference I'd pick is Perl's context based operation.
# Ruby requires explicit conversion with to_i
ruby -ane 'print if $F[1].to_i > 35'
perl -ane 'print if $F[1] > 35'
[1] https://github.com/learnbyexample/Command-line-text-processi...
- automatic associative array instantiation
- the return value of regular expressions with a capture group is the value matched by it (in Ruby, the closest to this is `[/regex/, <group_i>]`)
[code lang=“ruby”]
((33..126).map { |i| i.chr }).to_a.shuffle[0..14].join
[/code]
14.times.map { rand(33..126).chr }.shuffle.join
At any rate, would probably want to use https://ruby-doc.org/stdlib-2.5.1/libdoc/securerandom/rdoc/S... for password generation.
Also, I think you might just want an alphabet and use sample: https://ruby-doc.org/core-2.5.1/Array.html#method-i-sample
# unsure if you need a:
require 'securerandom'
(33..126).sample(14, random: SecureRandom).map(&:chr).join
File.readlines('/usr/share/dict/words').map(&:strip).shuffle.first(5).map(&:capitalize).join
=> "PanChloroformateParoticTillotBrushoff" 1.upto(100){|n|puts'FizzBuzz'[i=n**4%-15,i+13]||n}For example, just yesterday it was to parse a log, grep for specific lines, pull out a time and a number per line, display name, number, and some number of characters afterwards as a quick abnd dirty graph of the magnitude to make it obvious if there were major outliers and to try to see trends over time. Still a one-liner.
That said, if rails has a super simple default startup that could serve a file, then it might be useful to start that as a one liner in select circumstances.