System Information - Novell LINUX ENTERPRISE SERVER 10 - INSTALLATION AND ADMINISTRATION 08-05-2008 Installation Manual

17.7 System Information

17.7.1 System Activity Information: sar
To use sar, sadc (system activity data collector) needs to be running. Check its status
or start it with rcsysstat {start|status}.
sar can generate extensive reports on almost all important system activities, among
them CPU, memory, IRQ usage, IO, or networking. With its many options, it is too
complex to explain further here. Refer to the man page for extensive documentation
with examples.
17.7.2 Memory Usage: free
The utility free examines RAM usage. Details of both free and used memory and
swap areas are shown:
tux@mercury:~> free
total
Mem: 515584
-/+ buffers/cache:
Swap: 658656
The options -b,-k,-m,-g show output in bytes, KB, MB, or GB, respectively. The
parameter -d delay ensures that the display is refreshed every delay seconds. For
example, free -d 1.5 produces an update every 1.5 seconds.
17.7.3 User Accessing Files: fuser
It can be useful to determine what processes or users are currently accessing certain
files. Suppose, for example, you want to unmount a file system mounted at /mnt.
umount returns "device is busy." The command fuser can then be used to determine
what processes are accessing the device:
tux@mercury:~> fuser -v /mnt/*
/mnt/notes.txt
used free
501704 13880
94072 421512
0 658656
USER PID ACCESS COMMAND
tux 26597 f....
shared buffers
0 73040
less
System Monitoring Utilities
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