HowTo: Flush Contents Of a Memcached Server Using Command Line

by on January 28, 2012 · 6 comments· LAST UPDATED March 3, 2014

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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?

Tutorial details
DifficultyEasy (rss)
Root privilegesNo
Estimated completion time1m
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
Escape character is ‘^]’.
Connection to closed by foreign host.

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

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{ 6 comments… read them below or add one }

1 javel February 5, 2012 at 1:26 pm



2 Chin July 30, 2013 at 3:26 pm



3 Johny March 3, 2014 at 10:06 am

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


4 Nix Craft March 3, 2014 at 10:36 am

The faq has been updated. I appreciate your post.


5 T.Mini March 3, 2014 at 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


6 JFG October 19, 2014 at 11:27 pm

With bash only:

echo flush_all >/dev/tcp/


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