bash 如何在命令行上通过管道输入 ruby -e？
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How to get piped input to ruby -e on command line?
提问by pixelearth
I'm trying to figure out how to write one liners on the bash console and pipe to ruby but I can't figure out how to get the input. This isn't working:
我试图弄清楚如何在 bash 控制台上编写一个衬垫并通过管道连接到 ruby，但我无法弄清楚如何获取输入。这不起作用：
echo "My String" | ruby -e "#{STDIN.read.first.downcase}"
How can I get the piped input in ruby?
如何在 ruby 中获取管道输入？
回答by Stefan
Ruby treats your line as a comment because it starts with a #.
Ruby 将您的行视为注释，因为它以#.
This would work:
这会起作用：
echo "My String" | ruby -e "puts gets.downcase"
Output:
输出：
my string
I've used Kernel#getsinstead of STDIN.gets:
我用过Kernel#gets而不是STDIN.gets：
Returns (and assigns to $_) the next line from the list of files in ARGV (or $*), or from standard input if no files are present on the command line
从 ARGV（或 $*）中的文件列表中返回（并分配给 $_）下一行，如果命令行上没有文件，则从标准输入返回（并分配给 $_）
If you want to process each line, you could use the -pflag. It's like wrapping your script in a while gets(); ... end; puts $_block. Ruby reads each input line into $_, evaluates your script and outputs $_afterwards:
如果你想处理每一行，你可以使用-p标志。这就像将您的脚本包装在一个while gets(); ... end; puts $_块中。Ruby 将每个输入行读入$_，然后评估您的脚本并输出$_：
echo "Foo\nBar\nBaz" | ruby -pe '$_.downcase!'
Output:
输出：
foo
bar
baz
回答by Jerome Dalbert
Just
只是
echo "My String" | ruby -ne 'puts $_.downcase'
or
或者
echo "My String" | ruby -e "puts gets.downcase"
You get the idea.
你明白了。
回答by Dorian
Examples:
例子：
Strip all lines from extra spaces:
从多余的空格中去除所有行：
ls | ruby -e "STDIN.each_line.to_a.map(&:strip).each(&method(:puts))"
Randomly colorize each line:
随机为每一行着色：
ls | ruby -e "require 'colorize'; STDIN.each_line { |l| print l.colorize(String.colors.sample) }"
Sort lines by length:
按长度对行进行排序：
ls | ruby -e "puts STDIN.each_line.to_a.sort_by(&:size).reverse"
Sort files by file size:
按文件大小对文件进行排序：
ls -l | ruby -e 'STDIN.first; puts STDIN.each_line.to_a.map { |l| [l.split[4].to_i, l.split[8]] }.sort_by(&:first).reverse.map { |l| l.join("\t") }'
etc. etc.
等等等等
