added README

README.md

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+raou
+====
+raou is a lightweight sudo-like tool for Linux. It allows a user to 
+execute programs as another user without entering the password. However,
+the programs (including the parameters) a user can run are explicitly
+specified by the administrator.
+
+Originally written in C, it's now reimplemented in Rust.
+
+By default, raou looks in  /etc/raou.d/ for config files. If you run
+"raou backup", it will look for /etc/raou.d/backup.
+
+Example config file:
+
+user john
+target_user root
+path /usr/local/bin/script.sh
+
+
+*user* is the name of the user who you want to give permissions to 
+execute *path* as the *target_user*.  
+
+*path* must contain the absolute path. 
+
+Optional fields
+---------------
+*args*: If you want to leave out optional arguments (argv) to *path*, 
+simply don't  include this. Otherwise, simply specify them
+args -v -ltr 
+
+*allow_args*: Allow arbitrary arguments, so:
+raou backup /path
+
+Will launch "path" as specified in the file for the backup entry, but 
+with "/path" as argv[1] instead of the arguments specified with "args".
+
+*no_new_privs*: Defaults to 1. Processes launched with this option active
+won't be able to gain more privileges, even when they call setuid programs.
+
+*env_vars*: A comma-separated list of environment variables to inherit
+from the current environment. Everything else will be wiped (but others
+like HOME, SHELL etc. will be appropriately set). 
+
+*argv0*: Set this option if you want to provide your own value as "argv0"
+The default is the name of the launched binary (not the whole path).