Ruby中STDIN的最佳实践？

胡志

2023-12-01

本文翻译自：Best practices with STDIN in Ruby?

I want to deal with the command line input in Ruby: 我想处理Ruby中的命令行输入：

> cat input.txt | myprog.rb
> myprog.rb < input.txt
> myprog.rb arg1 arg2 arg3 ...

What is the best way to do it? 最好的方法是什么？ In particular I want to deal with blank STDIN, and I hope for an elegant solution. 特别是我想处理空白STDIN，我希望有一个优雅的解决方案。

#!/usr/bin/env ruby

STDIN.read.split("\n").each do |a|
   puts a
end

ARGV.each do |b|
    puts b
end

#1楼

参考：https://stackoom.com/question/195S/Ruby中STDIN的最佳实践

#2楼

while STDIN.gets
  puts $_
end

while ARGF.gets
  puts $_
end

This is inspired by Perl: 这是受Perl的启发：

while(<STDIN>){
  print "$_\n"
}

#3楼

I am not quite sure what you need, but I would use something like this: 我不太确定你需要什么，但我会用这样的东西：

#!/usr/bin/env ruby

until ARGV.empty? do
  puts "From arguments: #{ARGV.shift}"
end

while a = gets
  puts "From stdin: #{a}"
end

Note that because ARGV array is empty before first gets , Ruby won't try to interpret argument as text file from which to read (behaviour inherited from Perl). 请注意，因为ARGV数组在第一次gets之前是空的，所以Ruby不会尝试将参数解释为从中读取的文本文件（从Perl继承的行为）。

If stdin is empty or there is no arguments, nothing is printed. 如果stdin为空或没有参数，则不打印任何内容。

Few test cases: 几个测试用例：

$ cat input.txt | ./myprog.rb
From stdin: line 1
From stdin: line 2

$ ./myprog.rb arg1 arg2 arg3
From arguments: arg1
From arguments: arg2
From arguments: arg3
hi!
From stdin: hi!

#4楼

Something like this perhaps? 也许这样的事情？

#/usr/bin/env ruby

if $stdin.tty?
  ARGV.each do |file|
    puts "do something with this file: #{file}"
  end
else
  $stdin.each_line do |line|
    puts "do something with this line: #{line}"
  end
end

Example: 例：

> cat input.txt | ./myprog.rb
do something with this line: this
do something with this line: is
do something with this line: a
do something with this line: test
> ./myprog.rb < input.txt 
do something with this line: this
do something with this line: is
do something with this line: a
do something with this line: test
> ./myprog.rb arg1 arg2 arg3
do something with this file: arg1
do something with this file: arg2
do something with this file: arg3

#5楼

Following are some things I found in my collection of obscure Ruby. 以下是我在晦涩的Ruby系列中发现的一些东西。

So, in Ruby, a simple no-bells implementation of the Unix command cat would be: 所以，在Ruby中，Unix命令cat一个简单的no-bells实现将是：

#!/usr/bin/env ruby
puts ARGF.read

ARGF is your friend when it comes to input; 在输入方面， ARGF是你的朋友; it is a virtual file that gets all input from named files or all from STDIN. 它是一个虚拟文件，从命名文件或STDIN中获取所有输入。

ARGF.each_with_index do |line, idx|
    print ARGF.filename, ":", idx, ";", line
end

# print all the lines in every file passed via command line that contains login
ARGF.each do |line|
    puts line if line =~ /login/
end

Thank goodness we didn't get the diamond operator in Ruby, but we did get ARGF as a replacement. 谢天谢地，我们没有得到Ruby中的钻石操作符，但我们确实将ARGF作为替代品。 Though obscure, it actually turns out to be useful. 虽然模糊不清，但它实际上证明是有用的。 Consider this program, which prepends copyright headers in-place (thanks to another Perlism, -i ) to every file mentioned on the command-line: 考虑一下这个程序，该程序在命令行中提到的每个文件上就地存在版权标题（感谢另一个Perlism， -i ）：

#!/usr/bin/env ruby -i

Header = DATA.read

ARGF.each_line do |e|
  puts Header if ARGF.pos - e.length == 0
  puts e
end

__END__
#--
# Copyright (C) 2007 Fancypants, Inc.
#++

Credit to: 归功于：

#6楼

I'll add that in order to use ARGF with parameters, you need to clear ARGV before calling ARGF.each . 我要补充一点，为了使用带有参数的ARGF ，你需要在调用ARGF.each之前清除ARGV 。 This is because ARGF will treat anything in ARGV as a filename and read lines from there first. 这是因为ARGF会将ARGV中的任何内容视为文件名并首先从那里读取行。

Here's an example 'tee' implementation: 这是一个'tee'实现示例：

File.open(ARGV[0], 'w') do |file|
  ARGV.clear

  ARGF.each do |line|
    puts line
    file.write(line)
  end
end

Ruby中STDIN的最佳实践？

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