Setting default permissions for newly created files and sub-directories under a directory in Linux?

user_67829 0
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I have a bunch of long-running scripts and applications that are storing output results in a directory shared amongst a few users. I would like a way to make sure that every file and directory created under this shared directory automatically had u=rwxg=rwxo=r permissions.

I know that I could use umask 006 at the head off my various scripts, but I don't like that approach as many users write their own scripts and may forget to set the umask themselves.

I really just want the filesystem to set newly created files and directories with a certain permission if it is in a certain folder. Is this at all possible?

Update: I think it can be done with POSIX ACLs, using the Default ACL functionality, but it's all a bit over my head at the moment. If anybody can explain how to use Default ACLs it would probably answer this question nicely.

umask acl permissions linux
5 Answers

To get the right ownership, you can set the group setuid bit on the directory with 

chmod g+rwxs dirname

This will ensure that files created in the directory are owned by the group. You should then make sure everyone runs with umask 002 or 007 or something of that nature---this is why Debian and many other linux systems are configured with per-user groups by default.

I don't know of a way to force the permissions you want if the user's umask is too strong.

Norman_Ramsey_416610

It's ugly, but you can use the setfacl command to achieve exactly what you want.

On a Solaris machine, I have a file that contains the acls for users and groups. Unfortunately, you have to list all of the users (at least I couldn't find a way to make this work otherwise):

user::rwx
user:user_a:rwx
user:user_b:rwx
...
group::rwx
mask:rwx
other:r-x
default:user:user_a:rwx
default:user:user_b:rwx
....
default:group::rwx
default:user::rwx
default:mask:rwx
default:other:r-x

Name the file acl.lst and fill in your real user names instead of user_X.

You can now set those acls on your directory by issuing the following command:

setfacl -f acl.lst /your/dir/here
Manni_74980

I don't think this will do entirely what you want, but I just wanted to throw it out there since I hadn't seen it in the other answers.

I know you can create directories with permissions in a one-liner using the -m option:

mkdir -m755 mydir

and you can also use the install command:

sudo install -C -m 755 -o owner -g group /src_dir/src_file /dst_file
user_87483080
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