Confusing behavior of File.dirname

07 Nov 2022 | category: ruby-3.1.2 | Comments
#ruby #tech

If you are using File.dirname to get the directory path and delete and do some other processing on path, then make sure you consider below use cases.

irb(main):001:0> File.dirname("")
=> "."
irb(main):002:0> File.dirname("   ")
irb(main):002:0> File.dirname("   ")
=> "."
irb(main):003:0> File.dirname("   foo")
=> "."
irb(main):004:0> File.dirname("   foo/bar")
=> "   foo"
irb(main):005:0> File.dirname("foo/bar")
=> "foo"
irb(main):006:0>

If dirname received empty string or string withouth / then it returns the current directory.

Not sure if this is a bug or feature 😅

To get absolute path you should always use File.expand_path

File.expand_path(File.dirname(__FILE__))

If you are on above Ruby 2.0 then File.expand_path('..', __FILE__) can be use to get current path

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