2017-06-04 11:23:28 +00:00
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# Ruby is a dynamic, reflective, object-oriented, general-purpose programming language
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# ruby is a ruby interpreter
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# invoke Ruby from the command line to run the script foo.rb
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ruby foo.rb
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# pass code as an argument
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ruby -e 'puts "Hello world"'
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# The -n switch acts as though the code you pass to Ruby was wrapped in the following:
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# while gets
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2020-01-25 05:04:13 +00:00
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# # code here
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# end
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2017-06-04 11:23:28 +00:00
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ruby -ne 'puts $_' file.txt
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2019-10-15 08:55:32 +00:00
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# Beware that with the -n switch $_ contains newline character in the end.
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# With the addition of -l switch each line read has the newline character removed.
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ls | ruby -lne 'File.rename($_, $_.upcase)'
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2017-06-04 11:23:28 +00:00
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# The -p switch acts similarly to -n, in that it loops over each of the lines in the input
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# after your code has finished, it always prints the value of $_
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# Example: replace e with a
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echo "eats, shoots, and leaves" | ruby -pe '$_.gsub!("e", "a")'
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# BEGIN block executed before the loop
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echo "foo\nbar\nbaz" | ruby -ne 'BEGIN { i = 1 }; puts "#{i} #{$_}"; i += 1'
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