Update README

README.md

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 # netgiv
 
-TBD
+## What is this?
+
+`netgiv` is a single binary client and server to facilitate sending files across
+your local network quickly and easily.
+
+It uses a familiar unix pipeline paradigm, so files can be moved between machines
+as part of a pipeline, obviating the need for dealing with temporary files.
+
+`netgiv` automatically detects "copy" (stdin is a pipe) or "paste" (stdout is a pipe) modes, allowing intuitive use like:
+
+    host-A$ pg_dumpall | netgiv
+
+    host-B$ netgiv | psql restoredb
+
+Note that since netgiv uses a persistent server, there is no need to setup both ends
+of the pipeline in advance.
+
+All data is encrypted in flight (though not in the temporary files on the server). Access to the server is granted by an authentication token (preshared key) of your
+choice.
+
+## Install
+
+### Binary release
+
+Grab the appropriate version from https://github.com/tardisx/netgiv/releases, unzip
+and place the binary somewhere on your $PATH.
+
+### Compiling from source
+
+    go install github.com/tardisx/netgiv@latest
+
+`netgiv` should end up on your go binary path.
+
+### Compiling from source
+
+Clone this repository, run `go build`.
+
+## Configuration
+
+Configuration of `netgiv` is via a YAML configuration file in $HOME/.netgiv/config.yaml.
+
+Run `netgiv --help-config` for a sample config file.
+
+The server requires the 'authtoken' and 'port' configuration keys to be set.
+
+The client requires the 'authtoken', 'port' and 'address' configuration keys to be 
+set.
+
+* `authtoken` - this is any arbitrary string, you should choose something not easy to
+  guess or type
+* `port` - this is the TCP port the server will listen on (and that the client will
+  connect to)
+* `address` - the IP address or hostname of the `netgiv` server
+
+## Running
+
+To run a server, just run:
+
+    netgiv --server
+
+`netgiv` will run in the foreground and log accesses to it.
+
+On any client, run:
+
+    echo "Hello" | netgiv
+
+To check for success, try:
+
+    netgiv | cat 
+
+You should see "hello" echoed on your terminal.
+
+To check the list of files on the server:
+
+    netgiv -l
+
+### Alternative ways of providing the authtoken
+
+It's possible that you do not trust the hosts you are running the `netgiv` client on,
+or otherwise not want to store your authtoken in a file on there. If that is the case
+there are a couple of alternate options:
+
+#### ENV var
+
+The environment variable NETGIV_AUTHTOKEN can be used to provide the authtoken. A 
+common way to leverage this is to send it when you ssh to a remote host via the SendEnv option of ssh.
+
+#### Interactive
+
+If the authtoken has not been set by any of the above methods, it will be prompted
+for interactively (it will not be echoed to the screen).
+
+# Other notes
+
+## Temporary file storage
+
+The `netgiv` server will store files in your normal system temporary dir. They will 
+be deleted when the server shuts down (SIGTERM).
+
+## Window support
+
+Windows support is marginal, at best, mostly because of the lack of POSIX style 
+pipes. Bug reports and suggestions for workarounds are welcome.