chmod command is not working in shell script - bash

Question

I am writing a script that needs to create a file if an argument is passed to he script.
If no argument is passed then it will ask for fileName but it needs to have default permission as -rwx- --- - ---.
I am using this command chmod a=-rwx to remove all the default permissions and then i am using chmod u=+rwx to get the desired permission as stated but it is not working.
Can anyone help please?
#!bin\bash
if [ $#==0 ]; then
echo "Please enter a file name?"
read fileName
if [ -f $fileName ]; then
echo "File already exist! Opening for Editing"
sleep 3
nano $fileName
else
echo "File created with the name $fileName"
echo "Opening $fileName for editing "
sleep 3
echo "#!bin\bash" >$fileName
nano $fileName
fi
elif [ -f $1 ]; then
echo "File already exists with the name $1"
echo "Opening for editing"
sleep 3
nano $1
else
fileName="$1"
chmod a=-rwx $fileName
chmod u=+rwx $fileName
echo "File created with the name $filename"
echo "Opening $fileName for editing "
echo "#!bin\bash" >$fileName
sleep 3
nano $1
fi

Answer 1

Your chmod syntax is incorrect. The operation is either = to set the mode to a specific value, + to add modes, or - to remove modes; you can't combine them with =+ and =-.
You can perform multiple operations on a single file by separating them with ,.
So it should be:
chmod go-rwx,u+rwx "$fileName"
Another problem:
if [ $#==0 ]
should be
if [ $# -eq 0 ]
Use -eq for numeric comparisons, and spaces are needed around operators in shell conditions.
Third problem: You're doing the chmod before you create the file. Put it after
echo "#!/bin/bash" >"$fileName"
Fourth problem: #!bin\bash should be #!/bin/bash.
Finally, remember to quote your variables, in case they contain spaces.