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28 lines
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28 lines
1.0 KiB
Plaintext
# ruby
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# Interpreter of object-oriented scripting language Ruby
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# Invoke Ruby; a dynamic, reflective, object-oriented, general-purpose
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# programming language; from the command line to run the provided script.
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ruby foo.rb
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# Execute Ruby code directly from the command-line.
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ruby -e 'puts "Hello world"'
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# The `-n` switch allows Ruby to execute code within a `while gets` loop.
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ruby -ne 'puts $_' file.txt
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# Beware that with the `-n` switch, `$_` contains newline character at the end.
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# With the addition of the `-l` switch, each line read has the aforementioned
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# newline character removed.
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ls | ruby -lne 'File.rename($_, $_.upcase)'
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# The `-p` switch acts similarly to `-n`, in that it loops over each of the
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# lines in the input, after your code has finished; it always prints the value
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# of `$_`.
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#
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# The following example replaces `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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