Using gets() gives "No such file or directory" error when I pass arguments to my script

Question

Hi I am making a simple ruby script practiced where I make a form using gets.chomp and arguments, the problem is that when gets.chomp use the script returns me an error when I apply the argument test.

The code:

#!usr/bin/ruby

def formulario(quien)
    while (1)
        print "[+] Word : "
        word = gets.chomp
        print quien + " -> " + word
    end
end

quien = ARGV[0]

formulario(quien)

The error:

[+] Word : C:/Users/test/test.rb:8:in `gets': No such file or directory @ rb_sysopen - test (Errno::E
NOENT)
        from C:/Users/test/test.rb:8:in `gets'
        from C:/Users/test/test.rb:8:in `formulario'
        from C:/Users/test/test.rb:17:in `<main>'

Can anyone help?

Not related to your problem, but `#!usr/bin/ruby` is missing a leading `/`; it should be `#!/usr/bin/ruby` ... This is only required for UNIX & UNIX-like systems, though, and isn't really used on Windows (except for CygWin). — Martin Tournoij, Dec 12 '14 at 23:25

Martin Tournoij · Accepted Answer · 2014-12-15T14:34:53.697

116

It looks like you want to the user to type some input by reading a line from STDIN, the best way to do this is by calling STDIN.gets and not gets. So your line becomes:

word = STDIN.gets.chomp

This is documented as IO.gets. STDIN is an instance of IO.

Right now, you're executing Kernel.gets, which does something different (emphasis mine):

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.

This appears to behave like STDIN.gets if ARGV is empty, but is not the same thing, hence the confusion.

edited Dec 15 '14 at 14:34

answered Dec 12 '14 at 23:20

Martin Tournoij

26,737
24
105
146

[`gets` defaults to being read from STDIN](http://www.ruby-doc.org/core-2.1.5/Kernel.html#method-i-gets), so `STDIN.gets` isn't necessary. – the Tin Man Dec 12 '14 at 23:33
14

@theTinMan I had the exact same error and specifying `STDIN` worked for me. – Joshua Pinter May 05 '15 at 14:38
1

I can confirm that using STDIN.gets instead solved this same issue for me too. – Harlin May 27 '16 at 21:16
Thanks. Unexpected convenience can lead to strange places. I think this behavior is bizarre, but if I was used to it I might find it handy instead. – nc. Jul 31 '16 at 16:18
2

weird, i didn't know `ARGV` interfered with `.gets`; this answer worked for me too – infinite-etcetera Oct 03 '16 at 22:00
The point being that if you run your program with command line arguments, you need to specify`STDIN`. – BobRodes Jul 22 '20 at 08:58

Reyhan Alhafizal Hamidi · Answer 2 · 2019-06-26T06:55:53.513

0

If your program handle empty argument nor non-empty argument. You can use this module (especially if you already use default gets everywhere)

# A module that help to use method gets no matter what the file argument is
module InputHelper
    # Handle input method based on its file argument
    def gets
        if ARGV.nil?
            Kernel.gets
        else
            STDIN.gets
        end
    end
end

and then you could include it on your class

require 'input_helper'
class YourClass
    ...
    include InputHelper
    ...
end

edited Jun 26 '19 at 06:55

answered Jun 26 '19 at 06:09

Reyhan Alhafizal Hamidi

13
1
3

There is an error in this module. ARGV, when no arguments are supplied, is an empty array, [], and will never be nil, therefore the conditional will always be false and always execute STDIN.gets – Scott Oct 09 '22 at 17:18

score 0 · Answer 3 · answered Oct 09 '22 at 17:34

I ran into this issue today in Ruby 3.1.2. I can also confirm that STDIN.gets avoids this problem. An alternative workaround is to set ARGV to an empty array prior to capturing input via gets. You can simply set

ARGV = []
gets.chomp # works fine here

or store them elsewhere if you must get input before you've dealt with them all

cli_args = ARGV.dup
ARGV.clear
gets.chomp # works fine here

Using gets() gives "No such file or directory" error when I pass arguments to my script

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