# peer channel

The `peer channel` command allows administrators to perform channel related
operations on a peer, such as joining a channel or listing the channels to which
a peer is joined.

## Syntax

The `peer channel` command has the following subcommands:

  * create
  * fetch
  * getinfo
  * join
  * list
  * signconfigtx
  * update

## peer channel
```
Operate a channel: create|fetch|join|list|update|signconfigtx|getinfo.

Usage:
  peer channel [command]

Available Commands:
  create       Create a channel
  fetch        Fetch a block
  getinfo      get blockchain information of a specified channel.
  join         Joins the peer to a channel.
  list         List of channels peer has joined.
  signconfigtx Signs a configtx update.
  update       Send a configtx update.

Flags:
      --cafile string                       Path to file containing PEM-encoded trusted certificate(s) for the ordering endpoint
      --certfile string                     Path to file containing PEM-encoded X509 public key to use for mutual TLS communication with the orderer endpoint
      --clientauth                          Use mutual TLS when communicating with the orderer endpoint
      --connTimeout duration                Timeout for client to connect (default 3s)
  -h, --help                                help for channel
      --keyfile string                      Path to file containing PEM-encoded private key to use for mutual TLS communication with the orderer endpoint
  -o, --orderer string                      Ordering service endpoint
      --ordererTLSHostnameOverride string   The hostname override to use when validating the TLS connection to the orderer.
      --tls                                 Use TLS when communicating with the orderer endpoint
      --tlsHandshakeTimeShift duration      The amount of time to shift backwards for certificate expiration checks during TLS handshakes with the orderer endpoint

Use "peer channel [command] --help" for more information about a command.
```


## peer channel create
```
Create a channel and write the genesis block to a file.

Usage:
  peer channel create [flags]

Flags:
  -c, --channelID string     In case of a newChain command, the channel ID to create. It must be all lower case, less than 250 characters long and match the regular expression: [a-z][a-z0-9.-]*
  -f, --file string          Configuration transaction file generated by a tool such as configtxgen for submitting to orderer
  -h, --help                 help for create
      --outputBlock string   The path to write the genesis block for the channel. (default ./<channelID>.block)
  -t, --timeout duration     Channel creation timeout (default 10s)

Global Flags:
      --cafile string                       Path to file containing PEM-encoded trusted certificate(s) for the ordering endpoint
      --certfile string                     Path to file containing PEM-encoded X509 public key to use for mutual TLS communication with the orderer endpoint
      --clientauth                          Use mutual TLS when communicating with the orderer endpoint
      --connTimeout duration                Timeout for client to connect (default 3s)
      --keyfile string                      Path to file containing PEM-encoded private key to use for mutual TLS communication with the orderer endpoint
  -o, --orderer string                      Ordering service endpoint
      --ordererTLSHostnameOverride string   The hostname override to use when validating the TLS connection to the orderer.
      --tls                                 Use TLS when communicating with the orderer endpoint
      --tlsHandshakeTimeShift duration      The amount of time to shift backwards for certificate expiration checks during TLS handshakes with the orderer endpoint
```


## peer channel fetch
```
Fetch a specified block, writing it to a file.

Usage:
  peer channel fetch <newest|oldest|config|(number)> [outputfile] [flags]

Flags:
      --bestEffort         Whether fetch requests should ignore errors and return blocks on a best effort basis
  -c, --channelID string   In case of a newChain command, the channel ID to create. It must be all lower case, less than 250 characters long and match the regular expression: [a-z][a-z0-9.-]*
  -h, --help               help for fetch

Global Flags:
      --cafile string                       Path to file containing PEM-encoded trusted certificate(s) for the ordering endpoint
      --certfile string                     Path to file containing PEM-encoded X509 public key to use for mutual TLS communication with the orderer endpoint
      --clientauth                          Use mutual TLS when communicating with the orderer endpoint
      --connTimeout duration                Timeout for client to connect (default 3s)
      --keyfile string                      Path to file containing PEM-encoded private key to use for mutual TLS communication with the orderer endpoint
  -o, --orderer string                      Ordering service endpoint
      --ordererTLSHostnameOverride string   The hostname override to use when validating the TLS connection to the orderer.
      --tls                                 Use TLS when communicating with the orderer endpoint
      --tlsHandshakeTimeShift duration      The amount of time to shift backwards for certificate expiration checks during TLS handshakes with the orderer endpoint
```


## peer channel getinfo
```
get blockchain information of a specified channel. Requires '-c'.

Usage:
  peer channel getinfo [flags]

Flags:
  -c, --channelID string   In case of a newChain command, the channel ID to create. It must be all lower case, less than 250 characters long and match the regular expression: [a-z][a-z0-9.-]*
  -h, --help               help for getinfo

Global Flags:
      --cafile string                       Path to file containing PEM-encoded trusted certificate(s) for the ordering endpoint
      --certfile string                     Path to file containing PEM-encoded X509 public key to use for mutual TLS communication with the orderer endpoint
      --clientauth                          Use mutual TLS when communicating with the orderer endpoint
      --connTimeout duration                Timeout for client to connect (default 3s)
      --keyfile string                      Path to file containing PEM-encoded private key to use for mutual TLS communication with the orderer endpoint
  -o, --orderer string                      Ordering service endpoint
      --ordererTLSHostnameOverride string   The hostname override to use when validating the TLS connection to the orderer.
      --tls                                 Use TLS when communicating with the orderer endpoint
      --tlsHandshakeTimeShift duration      The amount of time to shift backwards for certificate expiration checks during TLS handshakes with the orderer endpoint
```


## peer channel join
```
Joins the peer to a channel.

Usage:
  peer channel join [flags]

Flags:
  -b, --blockpath string   Path to file containing genesis block
  -h, --help               help for join

Global Flags:
      --cafile string                       Path to file containing PEM-encoded trusted certificate(s) for the ordering endpoint
      --certfile string                     Path to file containing PEM-encoded X509 public key to use for mutual TLS communication with the orderer endpoint
      --clientauth                          Use mutual TLS when communicating with the orderer endpoint
      --connTimeout duration                Timeout for client to connect (default 3s)
      --keyfile string                      Path to file containing PEM-encoded private key to use for mutual TLS communication with the orderer endpoint
  -o, --orderer string                      Ordering service endpoint
      --ordererTLSHostnameOverride string   The hostname override to use when validating the TLS connection to the orderer.
      --tls                                 Use TLS when communicating with the orderer endpoint
      --tlsHandshakeTimeShift duration      The amount of time to shift backwards for certificate expiration checks during TLS handshakes with the orderer endpoint
```


## peer channel list
```
List of channels peer has joined.

Usage:
  peer channel list [flags]

Flags:
  -h, --help   help for list

Global Flags:
      --cafile string                       Path to file containing PEM-encoded trusted certificate(s) for the ordering endpoint
      --certfile string                     Path to file containing PEM-encoded X509 public key to use for mutual TLS communication with the orderer endpoint
      --clientauth                          Use mutual TLS when communicating with the orderer endpoint
      --connTimeout duration                Timeout for client to connect (default 3s)
      --keyfile string                      Path to file containing PEM-encoded private key to use for mutual TLS communication with the orderer endpoint
  -o, --orderer string                      Ordering service endpoint
      --ordererTLSHostnameOverride string   The hostname override to use when validating the TLS connection to the orderer.
      --tls                                 Use TLS when communicating with the orderer endpoint
      --tlsHandshakeTimeShift duration      The amount of time to shift backwards for certificate expiration checks during TLS handshakes with the orderer endpoint
```


## peer channel signconfigtx
```
Signs the supplied configtx update file in place on the filesystem. Requires '-f'.

Usage:
  peer channel signconfigtx [flags]

Flags:
  -f, --file string   Configuration transaction file generated by a tool such as configtxgen for submitting to orderer
  -h, --help          help for signconfigtx

Global Flags:
      --cafile string                       Path to file containing PEM-encoded trusted certificate(s) for the ordering endpoint
      --certfile string                     Path to file containing PEM-encoded X509 public key to use for mutual TLS communication with the orderer endpoint
      --clientauth                          Use mutual TLS when communicating with the orderer endpoint
      --connTimeout duration                Timeout for client to connect (default 3s)
      --keyfile string                      Path to file containing PEM-encoded private key to use for mutual TLS communication with the orderer endpoint
  -o, --orderer string                      Ordering service endpoint
      --ordererTLSHostnameOverride string   The hostname override to use when validating the TLS connection to the orderer.
      --tls                                 Use TLS when communicating with the orderer endpoint
      --tlsHandshakeTimeShift duration      The amount of time to shift backwards for certificate expiration checks during TLS handshakes with the orderer endpoint
```


## peer channel update
```
Signs and sends the supplied configtx update file to the channel. Requires '-f', '-o', '-c'.

Usage:
  peer channel update [flags]

Flags:
  -c, --channelID string   In case of a newChain command, the channel ID to create. It must be all lower case, less than 250 characters long and match the regular expression: [a-z][a-z0-9.-]*
  -f, --file string        Configuration transaction file generated by a tool such as configtxgen for submitting to orderer
  -h, --help               help for update

Global Flags:
      --cafile string                       Path to file containing PEM-encoded trusted certificate(s) for the ordering endpoint
      --certfile string                     Path to file containing PEM-encoded X509 public key to use for mutual TLS communication with the orderer endpoint
      --clientauth                          Use mutual TLS when communicating with the orderer endpoint
      --connTimeout duration                Timeout for client to connect (default 3s)
      --keyfile string                      Path to file containing PEM-encoded private key to use for mutual TLS communication with the orderer endpoint
  -o, --orderer string                      Ordering service endpoint
      --ordererTLSHostnameOverride string   The hostname override to use when validating the TLS connection to the orderer.
      --tls                                 Use TLS when communicating with the orderer endpoint
      --tlsHandshakeTimeShift duration      The amount of time to shift backwards for certificate expiration checks during TLS handshakes with the orderer endpoint
```

## Example Usage

### peer channel create examples

Here's an example that uses the `--orderer` global flag on the `peer channel
create` command.

* Create a sample channel `mychannel` defined by the configuration transaction
  contained in file `./createchannel.tx`. Use the orderer at `orderer.example.com:7050`.

  ```
  peer channel create -c mychannel -f ./createchannel.tx --orderer orderer.example.com:7050

  2018-02-25 08:23:57.548 UTC [channelCmd] InitCmdFactory -> INFO 003 Endorser and orderer connections initialized
  2018-02-25 08:23:57.626 UTC [channelCmd] InitCmdFactory -> INFO 019 Endorser and orderer connections initialized
  2018-02-25 08:23:57.834 UTC [channelCmd] readBlock -> INFO 020 Received block: 0
  2018-02-25 08:23:57.835 UTC [main] main -> INFO 021 Exiting.....

  ```

  Block 0 is returned indicating that the channel has been successfully created.

Here's an example of the `peer channel create` command option.

* Create a new channel `mychannel` for the network, using the orderer at ip
  address `orderer.example.com:7050`.  The configuration update transaction
  required to create this channel is defined the file `./createchannel.tx`.
  Wait 30 seconds for the channel to be created.

  ```
    peer channel create -c mychannel --orderer orderer.example.com:7050 -f ./createchannel.tx -t 30s

    2018-02-23 06:31:58.568 UTC [channelCmd] InitCmdFactory -> INFO 003 Endorser and orderer connections initialized
    2018-02-23 06:31:58.669 UTC [channelCmd] InitCmdFactory -> INFO 019 Endorser and orderer connections initialized
    2018-02-23 06:31:58.877 UTC [channelCmd] readBlock -> INFO 020 Received block: 0
    2018-02-23 06:31:58.878 UTC [main] main -> INFO 021 Exiting.....

    ls -l

    -rw-r--r-- 1 root root 11982 Feb 25 12:24 mychannel.block

  ```

  You can see that channel `mychannel` has been successfully created, as
  indicated in the output where block 0 (zero) is added to the blockchain for
  this channel and returned to the peer, where it is stored in the local
  directory as `mychannel.block`.

  Block zero is often called the *genesis block* as it provides the starting
  configuration for the channel.  All subsequent updates to the channel will be
  captured as configuration blocks on the channel's blockchain, each of which
  supersedes the previous configuration.

### peer channel fetch example

Here's some examples of the `peer channel fetch` command.

* Using the `newest` option to retrieve the most recent channel block, and
  store it in   the file `mychannel.block`.

  ```
  peer channel fetch newest mychannel.block -c mychannel --orderer orderer.example.com:7050

  2018-02-25 13:10:16.137 UTC [channelCmd] InitCmdFactory -> INFO 003 Endorser and orderer connections initialized
  2018-02-25 13:10:16.144 UTC [channelCmd] readBlock -> INFO 00a Received block: 32
  2018-02-25 13:10:16.145 UTC [main] main -> INFO 00b Exiting.....

  ls -l

  -rw-r--r-- 1 root root 11982 Feb 25 13:10 mychannel.block

  ```

  You can see that the retrieved block is number 32, and that the information
  has been written to the file `mychannel.block`.

* Using the `(block number)` option to retrieve a specific block -- in this
  case, block number 16 -- and store it in the default block file.

  ```
  peer channel fetch 16  -c mychannel --orderer orderer.example.com:7050

  2018-02-25 13:46:50.296 UTC [channelCmd] InitCmdFactory -> INFO 003 Endorser and orderer connections initialized
  2018-02-25 13:46:50.302 UTC [channelCmd] readBlock -> INFO 00a Received block: 16
  2018-02-25 13:46:50.302 UTC [main] main -> INFO 00b Exiting.....

  ls -l

  -rw-r--r-- 1 root root 11982 Feb 25 13:10 mychannel.block
  -rw-r--r-- 1 root root  4783 Feb 25 13:46 mychannel_16.block

  ```

  You can see that the retrieved block is number 16, and that the information
  has been written to the default file `mychannel_16.block`.

  For configuration blocks, the block file can be decoded using the
  [`configtxlator` command](./configtxlator.html). See this command for an example
  of decoded output. User transaction blocks can also be decoded, but a user
  program must be written to do this.

### peer channel getinfo example

Here's an example of the `peer channel getinfo` command.

* Get information about the local peer for channel `mychannel`.

  ```
  peer channel getinfo -c mychannel

  2018-02-25 15:15:44.135 UTC [channelCmd] InitCmdFactory -> INFO 003 Endorser and orderer connections initialized
  Blockchain info: {"height":5,"currentBlockHash":"JgK9lcaPUNmFb5Mp1qe1SVMsx3o/22Ct4+n5tejcXCw=","previousBlockHash":"f8lZXoAn3gF86zrFq7L1DzW2aKuabH9Ow6SIE5Y04a4="}
  2018-02-25 15:15:44.139 UTC [main] main -> INFO 006 Exiting.....

  ```

  You can see that the latest block for channel `mychannel` is block 5.  You
  can also see the cryptographic hashes for the most recent blocks in the
  channel's blockchain.

### peer channel join example

Here's an example of the `peer channel join` command.

* Join a peer to the channel defined in the genesis block identified by the file
  `./mychannel.genesis.block`. In this example, the channel block was
  previously retrieved by the `peer channel fetch` command.

  ```
  peer channel join -b ./mychannel.genesis.block

  2018-02-25 12:25:26.511 UTC [channelCmd] InitCmdFactory -> INFO 003 Endorser and orderer connections initialized
  2018-02-25 12:25:26.571 UTC [channelCmd] executeJoin -> INFO 006 Successfully submitted proposal to join channel
  2018-02-25 12:25:26.571 UTC [main] main -> INFO 007 Exiting.....

  ```

  You can see that the peer has successfully made a request to join the channel.

### peer channel list example

  Here's an example of the `peer channel list` command.

  * List the channels to which a peer is joined.

    ```
    peer channel list

    2018-02-25 14:21:20.361 UTC [channelCmd] InitCmdFactory -> INFO 003 Endorser and orderer connections initialized
    Channels peers has joined:
    mychannel
    2018-02-25 14:21:20.372 UTC [main] main -> INFO 006 Exiting.....

    ```

    You can see that the peer is joined to channel `mychannel`.

### peer channel signconfigtx example

Here's an example of the `peer channel signconfigtx` command.

* Sign the `channel update` transaction defined in the file
  `./updatechannel.tx`. The example lists the configuration transaction file
  before and after the command.

  ```
  ls -l

  -rw-r--r--  1 anthonyodowd  staff   284 25 Feb 18:16 updatechannel.tx

  peer channel signconfigtx -f updatechannel.tx

  2018-02-25 18:16:44.456 GMT [channelCmd] InitCmdFactory -> INFO 001 Endorser and orderer connections initialized
  2018-02-25 18:16:44.459 GMT [main] main -> INFO 002 Exiting.....

  ls -l

  -rw-r--r--  1 anthonyodowd  staff  2180 25 Feb 18:16 updatechannel.tx

  ```

  You can see that the peer has successfully signed the configuration
  transaction by the increase in the size of the file `updatechannel.tx` from
  284 bytes to 2180 bytes.

### peer channel update example

Here's an example of the `peer channel update` command.

* Update the channel `mychannel` using the configuration transaction defined in
  the file `./updatechannel.tx`. Use the orderer at ip address
  `orderer.example.com:7050` to send the configuration transaction to all peers
  in the channel to update their copy of the channel configuration.

  ```
  peer channel update -c mychannel -f ./updatechannel.tx -o orderer.example.com:7050

  2018-02-23 06:32:11.569 UTC [channelCmd] InitCmdFactory -> INFO 003 Endorser and orderer connections initialized
  2018-02-23 06:32:11.626 UTC [main] main -> INFO 010 Exiting.....

  ```

  At this point, the channel `mychannel` has been successfully updated.

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