两道shell程序题目，帮忙看看

女狼一共舞

1.Write a shell script to display the odd lines of a given file.
2. Write a shell script using a directory as input, if the input is null, use current directory as input. The routine is used to find all files with suffix  ".c" and ".cpp", and  then compare each other to check out whether there exist two files having the same contents: if exist, print out the corresponding names of these files.

godxuli

#!/bin/sh
#for odd line
FLAG=1
for loop in `cat $1`
do
        if [ $FLAG -eq "1" ]; then
                echo $loop
                FLAG=0
        else
                FLAG=1
        fi
done

hunter410

1:
sed -n 'p;n' file

phoinix

1：
sed -n '1,${p;n}' file