Shell Programming and Scripting

I have run one file.but this file is two different directory is there.I wrote the if loop but one directory to find it the file and another directory is not find.

Code:

#!bin/bash
a=/tmp
mau="manual.sh"
if [ -s $mau ]
then
echo `ls -l $mau`
else
echo "file not there"
b=/scr #not find the directory
pwd #{o/p=/tmp this cmd not working}
echo `ls -l $mau`
echo "file is there"
else 
echo "file not there"
fi

---------- Post updated at 05:19 PM ---------- Previous update was at 04:45 PM ----------

To compare the files in 2 directories in fine, use diff, but for just names, find or ls, sort and comm. The comm tool is a lines in set tool. comm a b reads files a and b, assuming they are binary sorted unique, in sort order, identifying the a only lines, b only lines and both lines. The b only lines get a leading tab, and the both lines get 2 leading tabs, to put them in different columns. You can remove columns, like comm -23 says just a only lines.