linux shell script

change password
$passwd

who login?
$who
$who -H
$who -q

who is who?
$finger
$finger mary
$finger -s mary
$finger john@candy.ntc.edu.tw

talk
$talk mary
$mesg
$mesg n
$mesg y
$wall
the system is coming down in 10 mins.
^D

logout
$exit
$logout

unix file system
/--bin binary code
 --dev devices
 --etc other files
        --passwd
        --init
        --initd run level related files
        --conf config files
 --tmp temporary file
 --usr
....

$pwd
$cd
$ls -ltda
l list detail info, t sort by file m-time, d dir only, a include hidden file
information of listed file
file privilege, owner, group, size, time, name

$mkdir
$rmdir

$file
get file type info
$cat
$more [-crs] filename
c clear screen before print, show control character, replace multiple blank lines with single blank line

$tail -[number of lines] filename
$head -[number of lines] filename

$rm
$cp
$mv