Set-up shared folders

let-shared-folder-group.sh

#!/bin/bash

# first assign to your directory the permissions/ownership you want
chgrp -R gerda $1
chmod -R ug+rwX,o-rwx $1

# the sticky bit is needed to preserve the group ownership
chmod g+s `find $1 -type d`

# the others won't be able to see anything...
setfacl -R -d -m o::- $1
# ...but the group will
setfacl -R -d -m g::rwX $1

echo 'Done!'

let-shared-folder-users.sh

#!/bin/bash

# first edit existing permissions
setfacl -R -m u:user1:rwX u:user2:rwX [...] $1

# then set the default ones
setfacl -d -R -m u:user1:rwX u:user2:rwX [...] $1

echo 'Done!'