1) Write a shell script sum.sh that takes an unspecified number of command line arguments (up to 9) 
of ints and finds their sum. Modify the code to add a number to the sum only if the number is greater than 10 

	#! /bin/sh 
	sum=0 
	for var in "$@" 
	do  
	   if [ $var –gt 10 ]    
	      then     
		sum=`expr $sum + $var`    
	   fi 
	done 
	printf "%s\n" $sum 


	% sh 2.1.sh 2 4 5  -- run the script as


2) Write a shell script takes the name a path (eg: /afs/andrew/course/15/123/handin), 
   and counts all the sub directories (recursively)

	#! /bin/sh 
	ls –R $1 | wc –l 

	run the script as: % sh 2.2.sh /afs/andrew/course/15/123/handin 

3) Write a shell script that takes a file where each line is given in the format        
	F08,guna,Gunawardena,Ananda,SCS,CSD,3,L,4,15123 ,G ,,   
   
   Creates a folder for each user name (eg: guna) and 
   set the permission to rw access for user only (hint: use fs sa)

	#! /bin/sh 
	cat $1 | 
	while read line 
	do   
		userid=`echo $line | cut –d”,” –f2`   
		mkdir $userid   
		fs sa $userid $userid rw 
	done

4) Write a shell script that takes a name of a folder as a command line argument, 
   and produce a file that contains the names of all sub folders with size 0 
   (that is empty sub folders)

	#! /bin/sh 
	ls $1 | 
	while read folder 
	do
	   if [ -d $1/$folder ]   
	   then    
		files=`ls $1/$folder | wc –l`    
		if [ $files –eq 0 ]      
		then         
			echo $folder >> output.txt    
		fi   
	   fi 
	done

5) Write a shell script that takes a name of a folder, and delete all sub folders of size 0 

	#! /bin/sh 
	ls $1 | 
	while read folder 
	do
	    files=`ls $folder | wc –l`    
	    if [ files –eq 0 ]
	      then         
	         rmdir $folder    
	    fi 
	done

6) write a shell script that will take an input file and remove identical lines (or duplicate lines from the file) 

	#! /bin/sh 
	cat $1 | sort | 
	while read line 
	do
	  if [ $prev!=$line ]  
	     then    
		echo $line >> sorted.txt  
	  fi  
	  prev=$line 
	done