1. nc command – The nc (also know as netcat) utility is used for just about anything under the sun involving TCP or UDP.
2. telnet command – The telnet command is used to communicate with another host using the TELNET protocol.

netcat (nc) Command Example To Flush Contents Of Memcached Server

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
On some system it may be called netcat, so try it as follows to remove all data of a memcached server running on Linux:
echo 'flush_all' | netcat localhost 11211
Try nc:
nc 192.168.1.10 11211<<<"flush_all"
Where,

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

You can create a bash shell alias as follows in your ~/.bashrc file:

## bash shortcut ##
alias flush_mem_cache_server="echo 'flush_all' | netcat 127.0.0.1 11211"

And use it as follows:
$ flush_mem_cache_server

Telnet Command Example To Flush Contents Of Memcached Server

Type the following command:
telnet your-memcached-server-ip PORT
In this example connect to 192.168.1.10 11211 and issue the flush_all command as follows:
$ telnet 192.168.1.10 11211
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.

Use bash only to flush all the content from Memcached

The syntax is:

echo flush_all > /dev/tcp/127.0.0.1/11211

Conclusion

This page explained how to flush contents of a memcached server running on a Linux or Unix-like systems using telnet or nc commands. For more information, see this page here.