When should I use a trailing slash on a directory? [duplicate]

Question

Possible Duplicate:
How linux handles multiple path separators (/home////username///file)

Most commands I use in linux behave exactly the same whether I include the trailing slash / character on the end of a directory name or not.

For example:

ls /home/cklein
ls /home/cklein/

cp foo bar
cp foo/ bar/

When does this trailing slash matter? What is the semantic meaning of the trailing slash?

Answer 1

It is completely dependent on the tool. rm won't let you remove a symlink to a directory if there's a slash at the end, and rsync does different things if the remote file specification has a slash at the end.

Answer 2

One good example is moving a file into a directory:

mv some_file foo

vs.

mv some_file foo/

If foo doesn't exist, the first will rename some_file to foo, rather than the intended foo/some_file; the second will complain, which is what you want.

If foo does exists but isn't a directory, the first can clobber the foo file; again, the second will complain.

cp presents similar issues.

Working on some old versions of SunOS, I developed the habit of appending /., because the system actually ignored a trailing / on a file name; for example, /etc/motd/ would refer to the file rather than being an error. Later versions of SunOS / Solaris don't seem to have that problem.

Answer 3

foo/ is like foo/., so if foo is a symlink to a directory, foo/ is a directory (not a symlink), and if foo is not a directory or a symlink to a directory, then you get a ENOTDIR error for anything trying to access foo/. That's the behavior on Linux.

Behavior may differ on other systems.

See here and here and here to see what POSIX/SUS have to say about it.