1. Find and print number of lines in a file
	sed -n '$ =' InputFile 
        sed -n '$=' InputFile            #saves one keystroke

2. Find a pattern (say "E7") at given character location starting 829
	sed -nE '/^.{829}E7/' < InputFile


30. Generate a file with running numbers (10 lines, in this case)
	yes | head -n 10 | nl | sed 's/^Iy//' > OutFile
                                      #^I is cntrl V+tab

	yes | head -10 | nl -s " " | sed 's/ y//' > OutFile

        more OutFile
             1
             2
             3
             4
             5
             6
             7
             8
             9
            10

4.  Fold sets of "n" lines in the input file  into a single line
	sed -n 'N;N;s/\n//g;p' <OutFile
        will produce
        1     2     3
        4     5     6
        7     8     9

        The last line was dropped. If you wanted that printed as well

	sed -n '$p;N;s/\n//g;$p;N;s/\n//g;p' OutFile
	1     2     3
     	4     5     6
     	7     8     9
    	10
	
5. You have a file with some lines starting with numbers and others
   with alphabets. You wish to join linew which are contiguous and
   which start wtih alphabet.