How to read websocket response in linux shell

Writing a bash script to connect to GDAX's Websocket Feed at wss://ws-feed.gdax.com but curl doesn't seem to support this as I get

curl "wss://ws-feed.gdax.com"
curl: (1) Protocol "wss" not supported or disabled in libcurl

Assuming you have node installed, I would give wscat a shot; it is simple, intuitive, and powerful. Otherwise, @Pavel's answer has an abundance of venerable websocket client alternatives.

# install
npm install -g wscat

# use
wscat -c "wss://ws-feed.gdax.com"

Well, you can try to mimic the required headers to get some response using curl:

• https://gist.github.com/htp/fbce19069187ec1cc486b594104f01d0 or
• https://stackoverflow.com/questions/40907888/linux-bash-how-to-open-a-websocket-connection-as-client

Also, there are other ways to communicate with a WebSocket server, e.g.

• https://github.com/websockets/wscat
• https://github.com/bwasti/webpipe
• https://github.com/progrium/wssh

I'd like to add my own tool for this: websocat.

Example session with the service in question:

$ rlwrap  websocat wss://ws-feed.gdax.com

# Now enter this line (without the #) for the required JSON request:
# {"type":"subscribe","channels": [{ "name": "heartbeat", "product_ids": ["BTC-USD"] }]}

{"type":"subscriptions","channels":[{"name":"heartbeat","product_ids":["BTC-USD"]}]}
{"type":"heartbeat","last_trade_id":46274575,"product_id":"BTC-USD","sequence":6312079752,"time":"2018-07-12T22:32:42.655000Z"}
{"type":"heartbeat","last_trade_id":46274575,"product_id":"BTC-USD","sequence":6312079800,"time":"2018-07-12T22:32:43.656000Z"}
{"type":"heartbeat","last_trade_id":46274575,"product_id":"BTC-USD","sequence":6312079834,"time":"2018-07-12T22:32:44.656000Z"}
{"type":"heartbeat","last_trade_id":46274575,"product_id":"BTC-USD","sequence":6312079945,"time":"2018-07-12T22:32:45.656000Z"}
{"type":"heartbeat","last_trade_id":46274575,"product_id":"BTC-USD","sequence":6312079990,"time":"2018-07-12T22:32:46.657000Z"}
{"type":"heartbeat","last_trade_id":46274575,"product_id":"BTC-USD","sequence":6312080042,"time":"2018-07-12T22:32:47.657000Z"}
{"type":"heartbeat","last_trade_id":46274576,"product_id":"BTC-USD","sequence":6312080169,"time":"2018-07-12T22:32:48.657000Z"}

# To stop the feed, type this line: 
{"type":"unsubscribe","channels": [{ "name": "heartbeat", "product_ids": ["BTC-USD"] }]}
{"type":"subscriptions","channels":[]}

Besides a websocket client, websocat supports WebSocket server and other modes and is aimed to integrate websockets into "UNIX" world in general.

ws start connection by http protocol, you have to change ws to http and some extra headers like this:

curl --include \
     --no-buffer \
     --header "Connection: Upgrade" \
     --header "Upgrade: websocket" \
     --header "Host: example.com:80" \
     --header "Origin: http://example.com:80" \
     --header "Sec-WebSocket-Key: SGVsbG8sIHdvcmxkIQ==" \
     --header "Sec-WebSocket-Version: 13" \
     "https://ws-feed.gdax.com"

https://gist.github.com/htp/fbce19069187ec1cc486b594104f01d0

You can connect to your server using Telnet also

     telnet 120.22.37.128 6870

Once you connect you can send request in Json format

     {"requestType":"hi"}     

Here 6870 is port port and to open port you need to run

     sudo ufw allow 6870 

And to check pm2 logs you required to use below command

    pm2 logs 0

Hope this hepls.