[Bash]Script to Check C/C++ Header Files

Hello all,
I just wrote a quick bash script to validate the header files from the C/C++ source file. This code just extracts the header file from the source code and runs a quick search in "include" folder, and prints the result. Nothing new, just wanted to write a bash script for learning and fun.

There are many improvements, still to be done. Ideas, suggestions and constructive criticism is welcome.
Here's the code:

1. #!/bin/bash
2. #
3. # Description   : A quick 'n' dirty bash script for validating header files.
4. # Author        : RahulB
5. # Usage         : ./validate.sh SourceFile
6. # Platform      : GNU/Linux
7. # Greets to     : Anant Sir, Hackuin, b0nd bro, and all g4h members.
8. #
10. if [ ! $# = 1 ] ; then             #Checking for exact one command line argument
11.         printf "Usage : $0 SourceFile \n"      
12.         exit 1
13. fi
16. if [ ! -s $1 ] ; then          #Checking file's existence/ sufficient privilege
17.         printf "Error : Either file doesn't exist or you don't have sufficient privileges. \n"
18.         exit 1
19. fi
21. declare FILENAME="$1"
22. declare EXT="${FILENAME##.*}"           #Extracting file extension
23. declare WD=$(pwd)                       #Saving current working directory
24. declare VDIR=$(ls -F /usr/include/c++/ | grep '/')  #Extracting version directory
26. if [ "$EXT" = "cpp" ] ; then       #Determing whether it's C or C++ by file extension
27.         DIR="/usr/include/c++/$VDIR"    #C++ include directory
28. elif [ "$EXT" = "c" ] ; then
29.         DIR='/usr/include/'             #C include directory
30. else
31.         printf "Error : Use .cpp for C++ and .c for C source files.\n"
32.         exit 1;
33. fi
35. cat $1 | grep '#include' | cut -d '<' -f2 | cut -d '>' -f1 > demo.log  #Extracting header files' name
37. cd "$DIR"                                  #Changing directory to include folder
38. for LINE in $(cat "$WD/demo.log")          #Line-by-line processing
39. do
40.         if test -s "$LINE" ; then          #Checking if header file exists or not.
41.                 printf "$LINE exists. \n"
42.         else
43.                 printf "Check the header file $LINE. \n"
44.         fi
45. done
47. printf "\n\n"
49. exit 0                       

Thanks and Regards.
Cheers.