How to set same permissions for all files under a shared folder

I have a shared directory. The directory's groupid is dev and many users are members of the group dev. Now I need to give all the files created under the folder to have the same permission say, rwxrwxr--.

How would I do that? One solution that came to my mind is: I would need a 2 shell scripts executable by all members of the group开发者_Python百科. One script should change the umask after checking that the current directory's groupID is dev. The other should change the umask to the previous default value.

Please let me know how to do this in shell script.

You can avoid the use of shell scripts by applying a default POSIX ACL (Access Control List) to the shared directory. e.g. On linux:

setfacl -m d:u::rwx,d:g::rwx,d:o::r,d:g:dev:rwx /shared/dir

The default ACL applied to /shared/dir above overrides the user's umask setting when new files are subsequently created in /shared/dir. The following is cut from the acl(5) man page on linux:

OBJECT CREATION AND DEFAULT ACLs

The access ACL of a file object is initialized when the object is created with any of the creat(), mkdir(), mknod(), mkfifo(), or open() functions. If a default ACL is associated with a directory, the mode parameter to the functions creating file objects and the default ACL of the directory are used to determine the ACL of the new object:

1. The new object inherits the default ACL of the containing directory as its access ACL.

2. The access ACL entries corresponding to the file permission bits are modified so that they contain no permissions that are not contained in the permissions specified by the mode parameter.

Create a single shell script to copy files into the shared directory. In that shell script, set the permissions on the file after copying. Make sure the directory has the SGID bit set; all files created in the directory will automatically belong to the group that owns the directory - dev in your scenario. Note that MacOS X effectively always has the SGID bit set on directories; that is, when a file is created, its group is the group that owns the directory.

Chastise anyone who self-evidently does not use the shell script, leaving files with the incorrect permissions.

Worry about whether all files should be executable; documents should not.

Worry about whether all files should be writable; where is the version control system in all this?

(I'd be happier with 444 permissions on the files - except for the few programs where 554 might be sensible.)

The question of the title doesn't seem related to the question in the body, but to answer the question in the title:

id=$( stat -f %g directory )