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Pipe command to script

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# 1  
Old 09-08-2013
Pipe command to script
Hello to all,

Having a ruby script that works when an argument is given in command line in this way:
Code:
ruby script.rb input_to_ruby

To accept arguments as input, inside the ruby script has
Code:
File.open(ARGV[0])

input_to_ruby is generated by another command, so I need to create first input_to_ruby in order to give as argument to script.rb, in this way.
Code:
ls -laD file1 > input_to_ruby

How can I pipe the output of "ls" to avoid create first the input_to_ruby and do it directly? something like:
Code:
ls -laD file1 | script.rb

Thanks in advance
# 2  
Old 09-08-2013
Hello,

You can do it with xargs command:

Code:
ls -laD file1 | xargs script.rb

see man xargs for more informations.

Regards.
# 3  
Old 09-08-2013
Hello

I'm not sure if some parameter is missing in xarg command, I've tried both ways below and is not working.

Code:
ls -laD file1 | xargs script.rb
xargs: script.rb: No such file or directory

ls -laD file1 | xargs script.rb
script1F.rb:3:in `initialize': No such file or directory - (Errno::ENOENT)
        from script.rb:3:in `open'
        from script.rb:3:in `<main>'

# 4  
Old 09-08-2013
Try and see if this works:
Code:
ls -laD file1 | script.rb -

Last edited by Scrutinizer; 09-08-2013 at 08:04 AM..
# 5  
Old 09-08-2013
Sorry,
I have not read correctly the problem.
If this syntax is available in your shell (e.g: available in bash):
Code:
script.rb <(ls -alD file)

Beware: no space between '<' and '('
Regards.
# 6  
Old 09-08-2013
Hi Ophiuchus ,
Expanding on what disedorgue said, if:
Code:
ruby script.rb <(ls -laD file1)

won't work in your shell (recent versions of both bash and ksh support this syntax), some systems have a pathname in /dev or /proc that is a name for the process's file descriptor 0 (AKA standard input). For example, on Mac OS X, the following should work for you:
Code:
ls -laD file1 | ruby script.rb /dev/stdin

If neither of these work for you and you can't find a name for standard input in the filesystem hierarchy on your system, we might be able to help you find a way to make it work if you'd tell us what operating system and shell you are using.
These 2 Users Gave Thanks to Don Cragun For This Post:
Ophiuchus Scrutinizer
# 7  
Old 09-08-2013
Hello disedorgue and scrutinizer,

Thank you for the help.

I'm using cygwin, maybe it has some limitations but doesn't work with
Code:
ruby script.rb <(ls -laD file1)
nor
ls -laD file1 | script.rb -

Hello Don Cragun,

Thanks for share another option, works in two forms below:
Code:
ls -laD file1 | ruby script.rb /dev/stdin
and
ls -laD file1 | ruby script.rb

Many thanks all 3 for the time and willingness to help and share knowledge.

Best regards.
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