Recipe: Which, whereis, file, whatis, loadavg explained !

which
=====
$ which ls
/bin/ls


whereis
=======
$ whereis ls
ls: /bin/ls /usr/share/man/man1/ls.1.gz


file
====
$ file /bin/ls
/bin/ls: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.15, stripped

whatis
======
$ whatis ls
ls (1)               - list directory contents

Load average:
$ uptime 
 12:40:53 up  6:16,  2 users,  load average: 0.00, 0.00, 0.00

OR

$ cat /proc/loadavg