Ubuntu – Find files based on permission

If filesystem is mounted with the acl option (default in ext4 in any modern Ubuntu - if not, add it to /etc/fstab), you can use setfacl:

setfacl -m u:USERNAME:r FILENAME

would give user USERNAME read access to FILENAME.

This is from Ubuntu's security policy:

Execute-Permission Bit Required

• Applications, including desktops and shells, must not run executable code from files when they are both:

  • lacking the executable bit
  • located in a user's home directory or temporary directory.

• This includes *.desktop, *.jar, and *.exe files.

• Nothing may provide a workaround to run them anyway automatically ...

So yes, according to this policy, it should be possible to run a .desktop file without the executable bit set. According to this policy you would only have to move that file out from the /home/ and /tmp/ directories and then you can launch it without the executable bit set. This is in theory/according to the policy.

In practice nautilus will allow you to launch .desktop files without the executable bit set from the XDG_DATA_DIR directories and from the ~/.gnome2/ directory. You can check the XDG_DATA_DIRS with the echo $XDG_DATA_DIRS command. So if you put your .desktop file in in an XDG_DATA_DIR or in ~/.gnome2/ you will be able to launch it from nautilus without the executable bit set. At least on 12.04 it works like that. _{How is this in line with the aforementioned policy I do not know.}

For the examples.desktop mentioned in the question: That .desktop file is a different kind of .desktop file. It is a "Link", it doesn't want to execute anything, it basically works as a symlink. These kinds of .desktop files work everywhere.