How do I see if memcached is already running on my chosen port?
I am having some problems with memcached and one idea I am having is that perhaps it is already running on the port I am trying to run it on, started by some other user on our network. Is there a way to tell what memcached ports are currently in use?
netstat -ap | grep TheChosenPort#
and see if anything is listening on those TCP or UDP ports.
To see if it is running you could also try telnetting into the port:
telnet localhost 11211
If this works you will see the following (telling you that the given port is open):
Connected to localhost. Escape character is '^]'.
Now if memcached IS running you can see some basic stats by issuing the given command:
If this fails you will know that memcached is not running.
In Linux, check via netstat, e.g.
$ sudo netstat -nap | grep memcached tcp 0 0 127.0.0.1:11211 0.0.0.0:* LISTEN 5067/memcached
Use ps to filter the processes:
$ ps wuax | grep memcache 497 5067 0.0 1.3 384824 53928 ? Ssl Apr11 1:28 memcached -d -p 11211 -u memcached -m 64 -c 1024 -P /var/run/memcached/memcached.pid -l 127.0.0.1
The port can be found next to -p, e.g. -p 11211. If port hasn't been specified, default is 11211.
You can send stats command to the given port and see if the memcached responds, e.g.
exec 3<>/dev/tcp/localhost/11211; printf "stats\nquit\n" >&3; cat <&3
Use telnet to connect to the host and run stats (as above), e.g.
$ telnet localhost 11211 Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. stats STAT pid 23669 STAT uptime 433859
Then hit Ctrl-] and Ctrl-D to finish.
Use the following command
ps -U user | grep -v grep | grep memcached
If you're asking this question, it sounds like you're running a really old version. If you did this on a recent version, you'd see this:
% ./memcached failed to listen on TCP port 11211: Address already in use
You can check memcached status
service memcached status
You will see a line like this at the bottom:
└─1560 /usr/bin/memcached -vv -m 64 -p 11211 -u memcache -l 127.0.0.1 -P /var/run/memcached/memcached.pid
The -p 11211 is what port it's running on.