Give execution permission to directories but not to files

To give execution (search) permission to directories, but not to files, use:

chmod -R +X .

To assign all the permissions as in your example, use:

chmod -R u=rwX,g=rX,o= .

-R changes files and directories recursively, while +X sets execute/search only if the file is a directory or already has execute permission for some user. r and w are of course for reading and writing, respectively.

Mode X (upper x) is documented in both the traditional manual page¹ and the info documentation².

It should also work on other Unix like systems, e.g. FreeBSD, NetBSD or OpenBSD. Quoting from the chmod(1) man page of The Open Group Base Specifications Issue 7, 2018 edition:

The X perm symbol was adopted from BSD-based systems because it provides commonly desired functionality when doing recursive (-R option) modifications. Similar functionality is not provided by the find utility. Historical BSD versions of chmod, however, only supported X with op+; it has been extended in this volume of POSIX.1-2017 because it is also useful with op=. (It has also been added for op- even though it duplicates x, in this case, because it is intuitive and easier to explain.)

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¹ man 1 chmod
² info '(coreutils)Conditional Executability'

If you want to do it recursively, i.e., to directories within directories within directories, the command to use is:

 find /path/to/starting/directory -type d -exec chmod +x {} \;

This locates all and only subdirectories (-type d flag) of the directory /path/to/starting/directory, and then performs the required change of execute permission to each one of them. The space before \; is mandatory.