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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 11211<<<"flush_all"


  • – 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 11212 and issue the flush_all command as follows:
$ telnet 11212
Sample outputs:

Connected to cache01.nixcraft.net.in.
Escape character is ‘^]’.
Connection to cache01.nixcraft.net.in closed by foreign host.

Originally posted 2016-01-11 05:53:11.

About admin

I have been working with Linux based systems since 2002. I hope the article published on this site will be useful to those new to server administration.