I would like to do something like this in terminal
$ ruby quicksort.rb unsorted.txt
quicksort.rb is the ruby file I would like to run unsorted.txt is the input file that contains unsorted numbers. Is it possible to do something like this in ruby?
Thank you.
You can read the commandline arguments and do a file operation. to read arguments you can use
ARGV.each do|a|
puts "Argument: #{a}"
end
This way you can get the filename and get the content.
ARGF makes this kind of task easy, almost as easy as Perl's <> operator:
$ cat quicksort.rb
#!/usr/bin/ruby
ARGF.each do |line|
puts line
end
$ ruby quicksort.rb /etc/passwd
root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/bin/sh
bin:x:2:2:bin:/bin:/bin/sh
sys:x:3:3:sys:/dev:/bin/sh
...
You might like to bookmark this extremely helpful quick guide to Ruby IO.
For arguments, use argv
ARGV.each do|file|
file
end
Then you can read contents of the file :
f = File.open(file, File::RDONLY)
Just read from standard in, the shell can do this for you easily:
#!/usr/bin/env ruby
puts $stdin.read.reverse
Then use the "<" to forward the contents of the bar.txt file containing "foobar" to your program.
$ ruby foo.rb < bar.txt
raboof
Another solution that more matches what you want to do would be:
#!/usr/bin/env ruby
puts IO.read(ARGV[0]).reverse
running it:
$ ruby foo.rb bar.txt
raboof
While I do like solving stuff in Ruby I just want to point out:
> sort unsorted.txt > sorted.txt
if you have a decent (*nix) command line. But maybe you want to do more than just the sorting?
ruby quicksort.rb < unsorted.txt