Monitoring System Activity

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relatively easy. top also displays: the total operations time for the system

since the last reboot; load averages; process counts for various states; the

percentage of CPU time broken down between user, system, nice, and idle;

memory and swap space usage; as well as the list of the processes using the

largest amount of the machine resources.

fuser: Who has it?

Sometimes, when an attempt is made to umount a device, it is still in use by

another account. umount will report  device busy  under these circumstances.

So,  Who has it? , is the question which must be answered before that account

can be contacted and asked to relinquish the device. fuser is the answer to

this question.

Assume that a CD ROM device has been mounted and now the material has

been transferred, or installed, and it is time to unmount the device, but the

umount command fails because the device is still busy. Very often the System

Administrator has forgotten that some virtual console has the current working

path somewhere on the CD. When memory doesn't resolve the issue it is

possibly some other process and user account that are still using the device.

The command:

fuser  muv /cdrom

will list each account using the device mounted on /cdrom, along with the

PID of the command that is currently executing in that device path. Once

the account is identified, a message can be sent to the session indicating the

System Administrator's desire to mount something else on that device.