From: Kashyap Ivaturi <kashyap.ivaturi@...>
Date: 2010-09-28T08:25:32+09:00
Subject: Re: passing single backslash character as commang line argument

Brian Candler wrote:
> Kashyap Ivaturi wrote:0
>> Please let me know how to get the backslash character in the string in
>> the test2.rb program.
> 
> That depends.
> 
> If you insist on invoking system with a single string argument, it gets 
> passed to the shell to execute - something like /bin/sh -c "the string".
> 
> This means the shell breaks it into words, and you have to deal with the 
> shell's rules for handling quoting and backslashes:
> 
> irb(main):004:0> str = "\\"   # one backslash
> => "\\"
> irb(main):005:0> system("echo \"#{str}\"")
> sh: Syntax error: Unterminated quoted string
> => false
> irb(main):006:0> str = "\\\\" # two backslahses
> => "\\\\"
> irb(main):007:0> system("echo \"#{str}\"")
> \
> => true
> 
> If instead you use the multi-argument form of system, then you don't get 
> a shell - Ruby invokes the program directly with the arguments given. 
> This means you don't need to worry about backslashes, or even quoting.
> 
> That is:
> 
> system("/usr/bin/ruby", test2AbsolutePath, text)
> 
> will pass those three args, and you don't need to quote the text even if 
> it contains spaces, backslashes or whatever. I strongly recommend you go 
> this way.
> 
> To find the full path to the ruby interpreter, have a look at the 
> rbconfig library.


Brian,
I changed the code as you suggested, but I still do not get see the 
single backslash appearing in the string that gets sent to the test2.rb

Here's the code:
test1.rb:
test2AbsolutePath = "C:\\test2.rb"
text = "Sample Ruby '\\' String"
system("ruby", test2AbsolutePath, text)

test2.rb:
text  = ARGV[0]
puts "text: #{text}"

Current Output:
text: Sample Ruby '' String

Expected Output:
text: Sample Ruby '\' String

Please let me know what needs to be modified to get the single backslash 
in the output.



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