::change user informations::

how to change user informations (finger) such as:

Shell:
Full Name:
Office Location:
Office Phone:
Home Phone:
Other information:

this can be done using command: chfn

::change window manager::

how to change window manager in Linux
$ xwmconfig

selection to change to or from:

kde - K Desktop Environment
xfce - The Cholesterol Free Desktop Environment
fluxbox - Fluxbox window manager
blackbox - Blackbox window manager
wmaker - WindowMaker
fvwm2 - F Virtual Window Manager 2
twm - Tab Window Manager

run this command as a normal user, no special permission needed

::lsof & fuser::

check for open files:
$ lsof | grep /dev/device

or

fuser

http://www.idevelopment.info/data/Unix/General_UNIX/GENERAL_Troubleshootingthedeviceisbusy.shtml

::managing spam email::

with linux, i have no issue managing my spam email
just:

# cat /dev/null &>/var/mail/myemail

drools... bye bye spam!

::check free swap::

bash-3.1# free -bt
total used free shared buffers cached
Mem: 513269760 502034432 11235328 0 15708160 217698304
-/+ buffers/cache: 268627968 244641792
Swap: 1028116480 0 1028116480
Total: 1541386240 502034432 1039351808
bash-3.1#