spawn - command not found!

Your script is attempting to combine two interpreters. You have both #!/bin/bash and #!/usr/bin/expect. That won't work. You can only use one of the two. Since bash was first, your script is being run as a bash script.

However, within your script, you have expect commands such as spawn and send. Since the script is being read by bash and not by expect, this fails. You could get around this by writing different expect scripts and calling them from your bash script or by translating the whole thing to expect.

The best way though, and one that avoids the horrible practice of having your passwords in plain text in a simple text file, is to set up passwordless ssh instead. That way, the scp won't need a password and you have no need for expect:

1. First, create a public ssh key on your machine:

   ssh-keygen -t rsa
   

   You will be asked for a passphrase which you will be asked to enter the first time you run any ssh command after each login. This means that for multiple ssh or scp commands, you will only have to enter it once. Leave the passphrase empty for completely passwordless access.

2. Once you have generated your public key, copy it over to each computer in your network :

   while read ip; do 
    ssh-copy-id -i ~/.ssh/id_rsa.pub user1@$ip 
   done < IPlistfile.txt
   

   The IPlistfile.txt should be a file containing a server's name or IP on each line. For example:

   host1
   host2
   host3
   

   Since this is the first time you do this, you will have to manually enter the password for each IP but once you've done that, you will be able to copy files to any of these machines with a simple:

   scp file user@host1:/path/to/file
   

3. Remove the expect from your script. Now that you have passwordless access, you can use your script as:

   #!/bin/bash
   echo "I will fail if you give junk values!!"
   echo " "
   echo "Enter file name: "
   read filePath
   echo " "
   echo "Where you want to copy?"
   echo "Enter"
   echo "1. if Host1"
   echo "2. if Host2"
   echo "3. if Host3"
   read choice
   echo " "
   if [ $choice -eq "1" ]
   then
     scp filePath uname@host1:/usr/tmp   
   elif [ $choice -eq "2" ]
   then
     scp filePath uname@host2:/usr/tmp   
   elif [ $choice -eq "3" ]
   then
     scp filePath uname@host3:/usr/tmp   
   else
     echo "Wrong input"
   fi
   

Your code can be a lot more concise:

#!/bin/bash

read -p "Enter file name: " filePath
if ! [[ -r $filePath ]]; then
    echo "cannot read $filePath"
    exit 1
fi

PS3="Where you want to copy? "
select host in host1 host2 host3; do
    if [[ -n $host ]]; then
        expect <<END
            spawn scp "$filePath" uname@$host:/usr/tmp   
            expect "password"   
            send "MyPassword\r"
            expect eof
END
        break
    fi
done

If you set up ssh keys as suggested, it's even better:

    if [[ -n $host ]]; then
        scp "$filePath" uname@$host:/usr/tmp   
        break
    fi

spawn is an expect command. It will not work if your interpreter is /bin/bash.