Why netcat doesn't dumps the response?

Question

``` $ cat mass_insert.txt *3 $3 SET $4 key1 $6 value1 *3 $3 SET $4 key2 $6 value2 $ cat mass_insert.txt | nc localhost 6379 ``` If you see, I've redis commands for mass insert in a file `mass_insert.text`, I `cat` it to netcat and the commands get sent fine to redis but the response is not dumped. The question is WHY ? A simple `google.com` HEAD request with `netcat` works just fine, i.e., dumps the response - ``` $ printf "HEAD / HTTP/1.0

" | nc google.com 80 HTTP/1.0 302 Found Location: http://www.google.co.in/ Cache-Control: private Content-Type: text/html; charset=UTF-8 Set-Cookie: PREF=ID=cac6fac8de9b5d0c:FF=0:TM=1365352115:LM=1365352115:S=CVuSzOK8mrsfFczI; expires=Tue, 07-Apr-2015 16:28:35 GMT; path=/; domain=.google.com Set-Cookie: NID=67=K5KjAFxuDP5epZKDdvSf4oCe4FRP1AL8LG_9MEdsArn4Oz_UBG69H0KOMUiKLuVN-hH4NIUvHOLgmfh_82P5v6Nh-sGFrGXyCnQz0zD-Sj_QbzxQ6NIK0rahsxjvyTn7; expires=Mon, 07-Oct-2013 16:28:35 GMT; path=/; domain=.google.com; HttpOnly P3P: CP="This is not a P3P pol…

Accepted Answer

You may want to check the following points.

First, the line separator in Redis protocol is 
 (and not just 
). So you need to be sure that your input file includes those characters.

Then, netcat shutdowns the connection at the end of the input file (it may therefore not wait for a Redis reply). It probably depends on the version of netcat though. On my system:

```
$ od -c toto.txt
0000000   *   3  
   $   3  
   S   E   T  
   $   4  
   k   e   y
0000020   1  
   $   6  
   v   a   l   u   e   1  
   *   3  
   $
0000040   3  
   S   E   T  
   $   4  
   k   e   y   2  
   $   6
0000060  
   v   a   l   u   e   2

$ ( sed 's/$//' < toto.txt ; sleep 1 ) | netcat localhost 6379
+OK
+OK
```

The extra second gives netcat a chance to read Redis reply.

Note that redis-cli in --pipe mode is much better suited than netcat to perform massive injections through the Redis protocol.

Why netcat doesn't dumps the response?

Solution

Problem