lsyncd/examples/lgforce.lua

-----
-- User configuration file for lsyncd.
--
-- This example refers to one common challenge in multiuser unix systems.
--
-- You have a shared directory for a set of users and you want
-- to ensure all users have read and write permissions on all
-- files in there. Unfortunally sometimes users mess with their
-- umask, and create files in there that are not read/write/deleteable
-- by others. Usually this involves frequent handfixes by a sysadmin,
-- or a cron job that recursively chmods/chowns the whole directory.
--
-- This is another approach to use lsyncd to continously fix permissions.
--
-- One second after a file is created/modified it checks for its permissions
-- and forces group permissions on it.
--
-- This example regards more the handcraft of bash scripting than lsyncd.
-- An alternative to this would be to load a Lua-Posix library and do the
-- permission changes right within the onAction handlers.

----
-- forces this group.
--
local fgroup = "staff"

-----
-- script for all changes.
--
local command =
-- checks if the group is the one enforced and sets them if not
[[
perm=`stat -c %A ^sourcePathname`
if [ `stat -c %G ^sourcePathname` != ]]..fgroup..[[ ]; then
	/bin/chgrp ]]..fgroup..[[ ^sourcePathname || /bin/true;
fi
]] ..

-- checks if the group permissions are rw and sets them
[[
if [ `expr match $perm "....rw"` == 0 ]; then
	/bin/chmod g+rw ^sourcePathname || /bin/true;
fi
]] ..

-- and forces the executable bit for directories.
[[
if [ -d ^sourcePathname ]; then
	if [ `expr match $perm "......x"` == 0 ]; then
		/bin/chmod g+x ^^sourcePathname || /bin/true;
	fi
fi
]]

-- on startup recursevily sets all group ownerships
-- all group permissions are set to rw
-- and to executable flag for directories
--
-- the carret as first char tells Lsycnd to call a shell altough it
-- starts with a slash otherwisw
--
local startup =
[[^/bin/chgrp -R ]]..fgroup..[[ ^source || /bin/true &&
/bin/chmod -R g+rw ^source || /bin/true &&
/usr/bin/find ^source -type d | xargs chmod g+x
]]

local gforce = {
	maxProcesses = 99,
	delay        = 1,
	onStartup    = startup,
	onAttrib     = command,
	onCreate     = command,
	onModify     = command,
	-- does nothing on moves, they won't change permissions
	onMove       = true,
}

sync{gforce, source="/path/to/share"}