wish: chmod -R to handle directories and files differently

[Richard Neill]

Dear All,

May I suggest an enhancement to chmod? The problem is that, when using 
chmod -R, the permissions we want to apply to files are usually not the 
same as for directories, especially regarding the executable state.
Here are a few ideas for how this could work...

1.
Add a "-d" option that specifies a different permission for directories. Eg:
   chmod -R 644 -d 755 path/to/dir
   #This sets everything to 644 (as normal for chmod), but treats
   #directories specially, setting them to 755.


2.
Add a "-u" option for using the umask. E.g:
   chmod -R -u path/to/dir
   #This applies my standard umask, for both files and dirs. It would be
   #useful for fixing up broken permissions quickly.


3.
Add "-D" and -"F" options to mean "apply to directories only" or "apply 
to files only"
E.g.:
  chmod -RD  755 /path/to/dir
recursively sets directories 755, (and leaves files unaltered).
  chmod -RF  644 /path/to/dir
recursively sets files to 644, (and leaves directories unaltered).


Typical use-cases:

(a) I have several nested directories of photos that originated from a 
digital camera with a FAT filesystem. Therefore all the directories, 
subdirectories and files are mode 777. I want to remove the executable 
permission from the files, but not the directories.

=>     chmod -Ru  my/photos/

(alternative is some ugliness with "find -type d")



(b) I want to fix up my ~/ssh permissions:
=>    chmod -R 600 -d 700 ~/.ssh

(alternative is two invocations of chmod)


Thanks for your time - I hope you like my idea.

Richard