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Running Memcached on Ubuntu

Install Memcached via apt

sudo apt install memcached

Start a Memcached server

memcached
  • Start options
    • -c: max simultaneous connections (default: 1024)
    • -d: run as a daemon
    • -h: print out help manual
    • -l: interface to listen on
    • -m: item memory in megabytes (default: 64)
    • -u: assume identity of <username> (only when run as root)
    • -p: TCP port to listen on (default: 11211)
    • -P: save PID in <file>, only used with -d option
    • -v: verbose (print errors/warnings while in event loop)
    • -vv: very verbose (print client commands/responses)
  • Stop a Memcached server by ctrl + c or kill <MemcachedPID>

  • Test connection Start another terminal session, use telnet to connect the Memcached server.

    # connect to memcached default port
telnet localhost 11211

Memcached basic commands

  • stats: to list Memcached service information
  • add <key> <flags> <exptime> <bytes>\n<value>\n: add a key and return STORED if value stored successfully
    • <key>: name of the cached item
    • <flags>:
    • <exptime>: expired time for the cache, use 0 for the maximum allowed time
    • <byte>: the size of the cache data
    • <value>: the value of the cache
  • replace: Store this data, but only if the data already exists.
  • set <key> <flags> <exptime> <bytes>\n<value>\n: combination of add and replace, to ADD or UPDATE a key

  • get <key>: Command for retrieving data. Takes one or more keys and returns all found items.

  • Example:

    # To add/update a key "hello" with value "world"
set hello 1 0 5
world
# return STORED

get hello
# VALUE hello 1 5
# world
# END

Run Memcached as Docker container

Below is an example of pull a Memcached docker image and run Memcached server as a daemon process, bind localhost port 11212 to the container’s port 11211

docker run -d -p 11212:11211 --name memcached --rm memcached

Test Memcached through telnet command

telnet 127.0.0.1 11212

The output will be like:

Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.

And it is ready for your input command, test the connection by type in stats:

stats
# should list the stats of Memcached server

Exit telnet interface by quit command.

Stop the container:

docker container stop memcached

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References

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