How much memory is in the box? (all UNIX, OpenVMS)

How much memory is in this machine?

It would seem that answering this question ought to be easy; it is – but every system has the answer in a different place. Most put an answer of some sort into kernel messages reported by dmesg (AIX apparently does not).

Most systems have a program for system inventory which reports a variety of things, including memory.

Rather than go into great detail about each one, we’ll just put these out there for all of you to reference. Each environment has multiple commands that give available memory; each command is listed below.

Without further ado, here are a few answers to this burning question:


  1. dmesg | grep mem
  2. prtdiag | grep Memory
  3. prtconf -v | grep Memory


  1. bootinfo -r
  2. lsattr -E1 sys0 -a realmem
  3. getconf REAL_MEMORY


  1. dmesg | grep Physical
  2. /opt/ignite/bin/print_manifest | grep Memory
  3. machinfo | grep Memory


  1. dmesg | grep Memory
  2. grep -i memtotal /proc/meminfo
  3. free


  1. show mem /page



  1. dmesg | grep memory
  2. grep memory /var/run/dmesg.boot
  3. sysctl -a | grep mem

6 thoughts on “How much memory is in the box? (all UNIX, OpenVMS)”

  1. If you have OnlineDiag installed on your HP-UX box (and I really can’t think of why you wouldn’t), this is pretty handy in seeing memory information:

    echo “selclass qualifier memory;info;wait;infolog” | /usr/sbin/cstm

    1. I’d forgotten that utility. This information also can be gotten from /usr/sbin/mstm (text menu driven) and /usr/sbin/xstm (X display). I’m not sure if the others are scriptable like this; I think they may all be the same binary.

  2. If you are running a non-PAE kernel the mentioned Linux commands don’t give you the full picture.
    In that case you can try to make sense of the output of
    dmidecode -t memory

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