How to check whether a File exists

Question

I have an Array of Strings and I want to select only these Strings which are paths to files:

My path is "~/dlds/some_file.ics" where ~/dlds is a symlink to ~/archive/downloads on my system. The file has following permissions:

-rw-r--r--

My code (I tried several variants):

ARGV.select do |string|
    File.file? string # returns false
    Pathname.new(string).file? # returns false
    Pathname.new(string).expand_path.file? # returns false
end

I don't know what else to try.

I'm running Ruby 2.2.0 or 2.2.2.

I think the reason is in the `~/` directory. To check it try to pass the full path ie `/home/user/dlds/some_file.ics` — Nickolay Kondratenko, Sep 30 '15 at 08:07
ARGV: `["--debug", "~/dlds/some_file"]`. Using a full path doesn't work as well.. — musicmatze, Sep 30 '15 at 08:09

score 17 · Accepted Answer · answered Sep 30 '15 at 08:11

17

File.exist? File.expand_path "~/dlds/some_file.ics"

answered Sep 30 '15 at 08:11

Aleksei Matiushkin

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3

note this returns true if the path is also a directory. details here: http://stackoverflow.com/questions/8590098/ruby-function-to-check-file-existence – Crashalot Apr 21 '16 at 08:43

score 1 · Answer 2 · answered Sep 30 '15 at 08:14

Your question is a bit confusing. If you want to check if the file exists, you should just do as you did:

Pathname.new(file_name).file?

If you are using the ~ you will first have to expand the path, so write:

Pathname.new(file_name).expand_path.file?

If you want to check if the given file_name is a symlink, you can just do

Pathname.new(file_name).expand_path.symlink?

If you want to find the file the symlink points to, you have to follow the link:

File.readlink(Pathname.new(file_name).expand_path)

which will return the filename of the linked file, so if you really wanted you could do something like:

Pathname.new(File.readlink(Pathname.new(file_name).expand_path)).file?

to make sure the symlink is pointing to an existing file.

score 0 · Answer 3 · answered Sep 30 '15 at 07:57

0

I think File.readlink is what you are looking for

Returns the name of the file referenced by the given link. Not available on all platforms.

File.readlink("path/to/symlink")

answered Sep 30 '15 at 07:57

Arsen

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Results in `Errno::ENOENT: No such file or directory @ rb_readlink - ~/dlds/some_file` – musicmatze Sep 30 '15 at 07:58
This should work. From the error you show you supplied the incorrect filename. – nathanvda Sep 30 '15 at 08:05
The filename was auto-completed when I tried in irb, so no, I know that the file exists and the path is correct. – musicmatze Sep 30 '15 at 08:09

How to check whether a File exists

3 Answers3