linux command

--send message in linux:
* 메세지 브로드캐스트

  wall 메세지

  ctrl+D

*개인에게 메세지 보내기

  write userid pts/number

  ctrl+d

--display cpu information:
cat proc/cpuinfo

--mail in linux (when sendmail server is running) : 
-check mail : mail
-writing mail :
mail graphy21@gmail.com
subject: something
something
.

2*(ctrl+c) mean cancel.
-writing mail by file : mail -s 'subject' graphy21@gmail.com < some_file.ext

--check running demon in kernel:
ps acx
-check zombi process & kill that:
ps axj # 'z' in STAT field in output mean zombi
kill -l # list of signal which can be send to process
kill [-signal number || signal] PID # example : kill -9 973