我想在Ruby中处理命令行输入:

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

最好的方法是什么?我特别想处理空白的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

当前回答

你也可以使用STDIN。each_line和STDIN.each_line。To_a将其作为数组获取。

e.g.

STDIN.each_line do |line|
  puts line
end

其他回答

也许是这样的?

#/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

例子:

> 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

Ruby提供了另一种处理STDIN的方法:-n标志。它将整个程序视为在STDIN上的循环中(包括作为命令行参数传递的文件)。参见以下一行脚本:

#!/usr/bin/env ruby -n

#example.rb

puts "hello: #{$_}" #prepend 'hello:' to each line from STDIN

#these will all work:
# ./example.rb < input.txt
# cat input.txt | ./example.rb
# ./example.rb input.txt

我不太清楚你需要什么,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

注意,因为ARGV数组在第一次获取之前是空的,Ruby不会尝试将参数解释为要读取的文本文件(行为继承自Perl)。

如果stdin为空或没有参数,则不打印任何内容。

很少的测试用例:

$ 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!

我是这样做的:

all_lines = ""
ARGV.each do |line|
  all_lines << line + "\n"
end
puts all_lines
while STDIN.gets
  puts $_
end

while ARGF.gets
  puts $_
end

这是受到Perl的启发:

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