awk (continued)
-	General form of awk statements
pattern {action}
-	if the pattern is matched action is taken
-	default pattern matches every line
-	default action is print $0
-	two special paterns are BEGIN and END
-	Other examples
-	print out first field of all the lines which have null string
	as the second field
awk -F: '$2==""{print $1}' /etc/passwd
-	print out first field of all the lines which have tcsh in the last
	field
awk -F: '$NF~"tcsh"{print $1}' /etc/passwd

-	awk uses all the C operators plus more
== comparison
!= not equal
<,>,<=,>=
~ comparing regular expressions (not from C)
!~ is opposite of ~
&& means and
|| means or
! means not

-	sort command sort a file

awk -F: '{print $1,$(NF -2)}' /etc/passwd | sort +2

-	We are sorting the output from awk based on the third field
-	+2 specifies the offeset which will be the third field
-	-n ro sort numerically instead of alphabetically
-	-r for reverse
-	-t for field separator, -i for case insensitive sort
-	the command tr is used for translation
-	the following command translates uppercase to lowercase

tr A-Z a-z < /etc/passwd

 			Backups
-	Note all of these commands are executed on machine called satara
-	mount allows you to mount a file system
-	mount -F nfs wascana:/ /wascana
-	The above command mounts root partition from wascana at mount point
	/wascana
-	tar cvf /wascana/extra/satara.tar .
-	The above command tars everything from . down into a file
	/wascana/extra/satara.tar
-	option c is for creating or rewinding the device
-	option v for verbose
-	f specifies the device by default the device is /dev/rmt/0
-	tar tf /wascana/extra/satara.tar
-	above command gives us the table of contents for the tar file
-	tar xvf /wascana/extra/satara.tar ./.cshrc
-	above command extracts ./.cshrc from the tar file
-	if you did not specify the filename, every file is extracted.
-	tar backs up everything from the specified directory down,
	irrespective of the file system.
-	ufsdump command only backs up a file system
-	dump2 is similar to ufsdump
-	An example of ufsdump command:
ufsdump 0uf /dev/rmt/0hn /dev/dsk/c0t3d0s0
-	0 stands for complete backups
-	you can also specify 1,2,3...7 levels instead of 0
-	level 1 backsup everything modified from last level 0 backup
-	f specifies the device, default is /dev/rmt/0
-	n in 0hn stands for not rewind after backing up the current
	file system
-	the last argument is the file system
-	ufsrestore is used for extracting files. It may be better to do it
	through the sysadm.