How detect that a file is locked by another app?

[TIG]

out_name = UI.savepanel('Location', '' , "#{File.basename(model.path, ".*")}.txt")
begin
  if out_name && ! out_name.empty?
    if File.extname(out_name).downcase != ".txt"
      ### if the user erase the extension, we readd it!
      out_name += ".txt"
    end
    file = File.new(out_name, 'w')
    file.puts(%Q["blabla"])
    file.close()
  else
    puts "Canceled"
  end
rescue Exception => error
  puts error
  ### or do something else like
  UI.messagebox("#{error}\nFailed to export file #{file}")
end

[Iltis]

OK, will try it. Thank you!

[TIG]

Just noticed a typo!
I corrected the earlier code snippet...

if out_name &**&** ! out_name.empty?

One other thing to note is that some types of file are locked by the app that opens them - like a dxf.
But a txt file is opened by Notepad++.exe it is not locked, so its contents can be overwritten, you will then be asked when bringing that txt file's window foremost in Notepad++ if you want to reload it...

So try using the dxf file...
Or for a simple test write a .CSV file [remembering to force it to .csv, rather than .txt] AND have it already opened in Excel - which will lock it...

[Jim]

Did you try something like File.writable?("file")?

Class: File (Ruby 2.0.0)

Class : File - Ruby 2.0.0

(ruby-doc.org)

[Iltis]

TIG, your solution is working fine. Thank you very much.

@jim said:

Did you try something like File.writable?("file")?

Yes Jim, not working.

BR,
Renaud.

[Jim]

In that case I would write it like this. You might rescue StandardError also, but rescuing Exception is too broad. You generally want to rescue exceptions starting with the most-specific and work up to the least-specific.

[1] https://www.google.com/search?q=ruby+rescue+exception%26amp;ie=utf-8%26amp;oe=utf-8

def locked?(filename)
   locked = false
   begin
      file = File.open(filename, "w")
   rescue Errno;;EACCES => error
      locked = true
   ensure
      file.close if file
   end
   return locked
end

if $0 == __FILE__
   p locked?("test.txt")
end

[thomthom]

@jim said:

In that case I would write it like this. You might rescue StandardError also, but rescuing Exception is too broad. You generally want to rescue exceptions starting with the most-specific and work up to the least-specific.

+1

[thomthom]

Also, prefer opening files using block syntax so it always closes - saves you explicit rescue to close.

[Jim]

@unknownuser said:

Also, prefer opening files using block syntax so it always closes - saves you explicit rescue to close.

...which actually simplifies everything.

def write_to_file(filename)
   File.open(filename, "a") { |file|
      file.puts("Hello #{Time.now}")
   }
rescue Errno;;EACCES
   puts "Could not write to file."
end

[Iltis]

Thank you very much for these complementary solutions.

Renaud.