Can a Ruby script tell what directory it’s in?

Inspired by "Getting the source directory of a Bash script from within", what's the Ruby way to do this?

For older versions of Ruby (< 2.0), the script being run can be found using:

For newer versions of Ruby, try:

Using __dir__ will return the script path even after a call to Dir.chdir; whereas, using the older syntax may not return the path to the script.

Use `dir`

As of Ruby 2.0, __dir__ is the simplest way to get this. It

Returns the canonicalized absolute path of the directory of the file from which this method is called.

See the __dir__ documentation, and "Why is __FILE__ uppercase and __dir__ lowercase?".

use __dir__

File.dirname(__FILE__) is not a proper way to get directory where script is stored.

At start working directory and directory with script file is the same, but it may change.

For example:

Dir.chdir('..') do
    puts __dir__
    puts File.expand_path(File.dirname(__FILE__))
end

for script file stored in /Desktop/tmp running it will give output

/home/mateusz/Desktop/tmp
/home/mateusz/Desktop

ENV["PWD"] seems the simplest way for me under Linux. I don't know of an OS-agnostic way.

来源：https://stackoverflow.com/questions/2206714/can-a-ruby-script-tell-what-directory-it-s-in

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Can a Ruby script tell what directory it’s in?