Displays amount of free and used memory in the system.
free -m -->in Mega bytes.
free -t--->Display total summary for physical memory + swap space.
Displays information about your CPU.
Display lots of information about current memory usage.
Prints system information to the screen (kernel version, machine type,
Search for a pattern in a file or program output. For example, to find out
which TCP network port is used by the “nfs” service, you can do this:
grep "nfs" /etc/services
This looks for any line that contains the string “nfs” in the file “/etc/services”
and displays only those lines.
“Switch User”. Allows you to switch to another user's account temporarily.
The default account to switch to is the root/superuser account. Examples:
su - Switch the root account
su - - Switch to root, and log in with root's environment
su larry - Switch to Larry's account