Question

I’m new to working with files in Ruby, and I found the following issue.

When executing the following line:

'zip -r "c:\temp\a.zip" "c:\temp\a.txt"'

from IRB I receive the following:

=> "zip -r \"c:\\temp\\a.zip\" \"c:\\temp\\a.txt\""

and definitely file is not compressed. So my question here is:

1. Why does ruby add a wrapper

   \\

   around file path and

   \

   signs. If you could elaborate on this that would be really helpful as I wasn’t able to find info on backslashes

2. How to escape these signs?

My Environment:

Windows 7
jRuby 153

Answer 1

The backslashes are escapes.

In any case, if you’re just evaluating the string, that’s just the string-as-a-string. When you use single-quotes, backslashes are just backslashes, not escape characters. Internally, for a string to print a backslash, it must be escaped, so Ruby does it for you.

If you assigned it to a variable and called puts:

> 'zip -r "c:\temp\a.zip" "c:\temp\a.txt"'
 => "zip -r \"c:\\temp\\a.zip\" \"c:\\temp\\a.txt\"" 
> s = 'zip -r "c:\temp\a.zip" "c:\temp\a.txt"'
 => "zip -r \"c:\\temp\\a.zip\" \"c:\\temp\\a.txt\"" 
> puts s
zip -r "c:\temp\a.zip" "c:\temp\a.txt"

You’re also not actually doing anything–you’re just creating a string.

If you want to execute the string as a command, you need to be using back-ticks, not single-quotes. Also, both Ruby and Java are OS-agnostic, so you can use forward-slashes like normal people.