Strange ruby problem

Ruby
1

So i’ve cut the program down to about 4 lines to give the idea of
whats going on:

num = ARGV[0]
num2 = ARGV[1]
puts " #{num} #{num2} \n"
line = gets

if i give the program some input from the command line it fails and
sais " gets: No such file or directory -1"
yet if i supply no input the program goes straight to gets. This seems
fairly strange to me. Though when I did this:

num = ARGV[0]
num2 = ARGV[1]
puts " #{num} #{num2} \n"
STDOUT.flush
line = STDIN.gets

everything works normal. Why is this and whats going on? Thanks in
advance

Sincerely,
Chris Dancy

2

try without the last line, line = gets

On Wed, Sep 24, 2008 at 7:49 PM, [email protected] <

3

The program is trying to read from ARGV[0] , and there is no file with
the
name ARGV[0] that you have given.

On Wed, Sep 24, 2008 at 7:49 PM, [email protected] <

4

On Sep 24, 10:18 am, “[email protected]”
[email protected] wrote:

yet if i supply no input the program goes straight to gets. This seems
fairly strange to me. Though when I did this:

num = ARGV[0]
num2 = ARGV[1]
puts " #{num} #{num2} \n"
STDOUT.flush
line = STDIN.gets

everything works normal. Why is this and whats going on? Thanks in
advance

I think we need to see your command-line arguments and whether you’re
putting them before the name of the Ruby script or after. Are you
invoking the script like:

ruby script.rb arg1 arg2

or:

ruby arg1 arg2 script.rb

because the first is what you should be doing. Alternatively, do you
have RUBYOPT set or do you invoke any arguments on your #! line (if
you’re on a Unix-like system).

Eric

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5

On 24.09.2008 16:18, [email protected] wrote:

sais " gets: No such file or directory -1"
advance
As others have said: arguments are the problem. “gets” tries to read
from ARGF which is basically all ARGV values interpreted as files and
concatenated as streams. You typically use this for poor man’s cat:

ruby -e ‘ARGF.each {|line| puts line}’ foo bar baz

You can avoid the issue by doing

num = ARGV.shift
num2 = ARGV.shift
puts num, num2
line = gets

Cheers

robert

6

On Wed, Sep 24, 2008 at 1:29 PM, Robert K.
[email protected] wrote:

num2 = ARGV.shift
puts num, num2
line = gets

Cheers

   robert

As robert says.

I ran into this just the other day. ARGV has to be clear (empty), for
stdin to work for gets. (Pickaxe 2nd Ed., p. 180)

Todd

7

On Sep 24, 9:18 am, “[email protected]”
[email protected] wrote:

yet if i supply no input the program goes straight to gets. This seems

Sincerely,
Chris Dancy

Arguments on the command line are assumed
to be files to be read by “gets”.

E:>echo First line of file > temp.txt

E:>ruby -e “p gets” temp.txt
“First line of file \n”

Correct programs:

num = ARGV.shift
num2 = ARGV.shift
puts " #{num} #{num2}"
line = gets

num = ARGV[0]
num2 = ARGV[1]
puts " #{num} #{num2}"
line = $stdin.gets