CODEWITHSUNDEEP
rubyruby-1.9
Jason Kim
Jason Kim

Reputation: 19031

Running Ruby file with an input file in terminal?

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.

Upvotes: 2

Views: 1801

Answers (5)

froderik
froderik

Reputation: 4808

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?

Upvotes: 1

sunkencity
sunkencity

Reputation: 3472

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

Upvotes: 2

Sumit Bisht
Sumit Bisht

Reputation: 1517

For arguments, use argv

ARGV.each do|file|
file
end

Then you can read contents of the file :

f = File.open(file, File::RDONLY)

Upvotes: 2

Diode
Diode

Reputation: 25135

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.

Upvotes: 3

sarnold
sarnold

Reputation: 104050

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.

Upvotes: 3

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