Merge pull request #4347 from thisconnect/doc/cmd/add-chunker-options

chunker long description first shot

core/commands/add.go

@@ -71,6 +71,30 @@ its filename. For example:
 You can now refer to the added file in a gateway, like so:
 
   /ipfs/QmaG4FuMqEBnQNn3C8XJ5bpW8kLs7zq2ZXgHptJHbKDDVx/example.jpg
+
+The chunker option, '-s', specifies the chunking strategy that dictates
+how to break files into blocks. Blocks with same content can
+be deduplicated. The default is a fixed block size of
+256 * 1024 bytes, 'size-262144'. Alternatively, you can use the
+rabin chunker for content defined chunking by specifying
+rabin-[min]-[avg]-[max] (where min/avg/max refer to the resulting
+chunk sizes). Using other chunking strategies will produce
+different hashes for the same file.
+
+  > ipfs add --chunker=size-2048 ipfs-logo.svg
+  added QmafrLBfzRLV4XSH1XcaMMeaXEUhDJjmtDfsYU95TrWG87 ipfs-logo.svg
+  > ipfs add --chunker=rabin-512-1024-2048 ipfs-logo.svg
+  added Qmf1hDN65tR55Ubh2RN1FPxr69xq3giVBz1KApsresY8Gn ipfs-logo.svg
+
+You can now check what blocks have been created by:
+
+  > ipfs object links QmafrLBfzRLV4XSH1XcaMMeaXEUhDJjmtDfsYU95TrWG87
+  QmY6yj1GsermExDXoosVE3aSPxdMNYr6aKuw3nA8LoWPRS 2059
+  Qmf7ZQeSxq2fJVJbCmgTrLLVN9tDR9Wy5k75DxQKuz5Gyt 1195
+  > ipfs object links Qmf1hDN65tR55Ubh2RN1FPxr69xq3giVBz1KApsresY8Gn
+  QmY6yj1GsermExDXoosVE3aSPxdMNYr6aKuw3nA8LoWPRS 2059
+  QmerURi9k4XzKCaaPbsK6BL5pMEjF7PGphjDvkkjDtsVf3 868
+  QmQB28iwSriSUSMqG2nXDTLtdPHgWb4rebBrU7Q1j4vxPv 338
 `,
 	},