Using File Descriptors for Temporary Files and Temporary Directories

temp_files_directories.md

Using File Descriptors for Temporary Files and Temporary Directories

You can easily use file descriptors to create temporary files:

tmpfile=$(mktemp /tmp/abc-script.XXXXXX)
exec 3<>"$tmpfile"
echo 'Hello World' >"$tmpfile"
rm "$tmpfile"
cat <&3

In Python you can just use with tempfile.TemporaryFile(). It also does the same thing on supported operating systems.

What about directories? Can we get a "virtual" directory?

Well there are these things called directory descriptors.

It seems that it should be possible to create a directory, opening a directory descriptor, and then unlinking the directory path.

Then using the functions openat or *at functions to work on that descriptor.

However trying it to do this via Python's os.* functions that has the dir_fd parameter doesn't work. You can delete the directory, and but when using those functions, you end up with errors about FileNotFound. However the normal os.f* functions does work on the directory descriptor when the directory is deleted.