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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 on Linux or Unix-like systems?

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. You can send flush_all command using any one of the following method:

  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


echo 'flush_all' | netcat localhost 11211


nc 11211<<<"flush_all"


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

Telnet Command Example To Flush Contents Of Memcached Server

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

Connected to cache01.nixcraft.net.in.
Escape character is ‘^]’.
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)

{ 6 comments… add one }

  • javel February 5, 2012, 1:26 pm


  • Chin July 30, 2013, 3:26 pm


  • Johny March 3, 2014, 10:06 am

    $ telnet 11212 <- wrong port,
    should be: $ telnet 11211

    • Nix Craft March 3, 2014, 10:36 am

      The faq has been updated. I appreciate your post.

  • T.Mini March 3, 2014, 10:40 am

    Apart from memcached server, I had css/js on-fly minified cache stored on /var/www/.diskcache. To flush disk cache at /var/www/.diskcache:

    find  /var/www/.diskcache -type f -iname "*" -delete
  • JFG October 19, 2014, 11:27 pm

    With bash only:

    echo flush_all >/dev/tcp/

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