HowTo: Flush Contents Of a Memcached Server Using Command Line

I've installed memcached server under Linux but it is still showing old data. How do I flush the contents of a Memcached instance / server?

You can invalidate all existing cache items using the flush_all command. This command does not pause the server, as it returns immediately. It does not free up or flush memory at all, it just causes all items to expire.

netcat (nc) Command Example

The nc (netcat) command is a simple unix utility which reads and writes data across network connections, using TCP or UDP protocol. It can simply connect to the memcached instance and and invalidate all existing cache:

 
echo 'flush_all' | nc localhost 11211

 
echo 'flush_all' | netcat localhost 11211

 
nc 192.168.1.10 11211<<<"flush_all"

Where,

192.168.1.10 - memcached server instance
localhost - memcached server instance
11211 - memcached server port.

Telnet Command Example

Type the following command:
telnet your-memcached-server-ip PORT
In this example connect to 192.168.1.10 11212 and issue the flush_all command as follows:
$ telnet 192.168.1.10 11212
Sample outputs:

Trying 192.168.1.10...
Connected to cache01.nixcraft.net.in.
Escape character is ‘^]’.
flush_all
OK
quit
Connection to cache01.nixcraft.net.in closed by foreign host.

(Fig.01: telnet command in action - invalidate all existing cache items using flush_all command)