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I need to parse a basename in ruby a from file path which I get as input. Unix format works fine on Linux.

File.basename("/tmp/text.txt")

return "text.txt".

However, when I get input in windows format:

File.basename("C:Usersjohnnote.txt")

or

File.basename("C:\Users\john\note.txt")

"C:Usersjohnnote.txt" is the output (note that n is a new line there), but I didn't get "note.txt".

Is there some nice solution in ruby/rails?

Solution:

"C:\test\note.txt".split(/\|//).last
=> "note.txt"
"/tmp/test/note.txt".split(/\|//).last
=> "note.txt"

If the Linux file name doesn't contain , it will work.

Backslashes, while how Windows expresses things, are just a giant nuisance. Within a double-quoted string they have special meaning so you either need to do:

File.basename("C:\Users\john\note.txt")

Or use single quotes that avoid the issue:

File.basename('C:Usersjohnnote.txt')

Or use regular slashes which aren't impacted:

File.basename("C:/Users/john/note.txt")

Where Ruby does the mapping for you to the platform-specific path separator.

Try pathname:

require 'pathname'

Pathname.new('C:Usersjohnnote.txt').basename
# => #<Pathname:note.txt>

Pathname docs

Ref How to get filename without extension from file path in Ruby

I'm not convinced that you have a problem with your code. I think you have a problem with your test.

Ruby also uses the backslash character for escape sequences in strings, so when you type the String literal "C:Usersjohnnote.txt", Ruby sees the first two backslashes as invalid escape sequences, and so ignores the escape character. n refers to a newline. So, to Ruby, this literal is the same as "C:Usersjohnnote.txt". There aren't any file separators in that sequence, since n is a newline, not a backslash followed by the letter n, so File.basename just returns it as it receives it.

If you ask for user input in either a graphical user interface (GUI) or command line interface (CLI), the user entering input needn't worry about Ruby String escape sequences; those only matter for String literals directly in the code. Try it! Type gets into IRB or Pry, and type or copy a file path, and press Enter, and see how Ruby displays it as a String literal.

On Windows, Ruby accepts paths given using both "/" (File::SEPARATOR) and "\" (File::ALT_SEPARATOR), so you don't need to worry about conversion unless you are displaying it to the user.