Ruby: No such file or directory @ rb_sysopen - testfile (Errno::ENOENT)

Question

I want to write something to a file.

# where userid is any intger [sic]
path = Rails.root + "public/system/users/#{user.id}/style/img.jpg" 
File.open(path, 'wb') do |file|
  file.puts f.read
end 

When this code is executed, I'm getting this error. I know this folder doesn't exist, but File.open with w mode creates a new file if it doesn't exist.

Why is this not working?

Solution 1

File.open(..., 'w') creates a file if it does not exist. Nobody promised it will create a directory tree for it.

Another thing, one should use File#join to build directory path, rather than dumb string concatenation.

path = File.join Rails.root, 'public', 'system', 'users', user.id.to_s, 'style'

FileUtils.mkdir_p(path) unless File.exist?(path) 
File.open(File.join(path, 'img.jpg'), 'wb') do |file|
  file.puts f.read
end

Solution 2

Trying to use gets inside a rake task? You may be seeing this error message:

Errno::ENOENT: No such file or directory @ rb_sysopen

Did you try searching the error, and end up on this page? This answer is not for the OP, but for you.

Use STDIN.gets. Problem solved. That's because just using gets resolves back to $stdin.gets and rake is overriding the global variable so that gets tries to open a file handle that doesn't exist. Here's why:

What's the difference between gets.chomp() vs. STDIN.gets.chomp()?

Comments

[user1934428]

Just being curious: Why is is File.join advisable here? It joins the path components always with the platform specific separator (for instance, ` on Windows). While there **are** cases, where this is what we want to achive, we usually try to stick with /` on all platforms, because this gives less headache with respect of portability. In the case of the code posted here, I don't see why platform-specific file separators could be an advantage.

[Aleksei Matiushkin]

@user1934428 “we usually try to stick with / on all platforms, because this gives less headache with respect of portability”—besides this is nonsense, using File.join helps to avoid silly mistakes like the one in the OP: Rails.root does not end with a slash and using + gives /railsrootpublic/ (note the slash miss above.)

[ashwintastic]

@mudasobwa: In my rails console Rails.root + "bla/bla" GIves correct path :)

[ashwintastic]

@mudasobwa : it worked but I have to make some changes like Dir.mkdir only create directory not a directory tree, I used FileUtils.mkdir_p : thnk for the help

[bschlueter]

This also applies to use of gets inside of a Vagrantfile.