bash please

Write a script namedbackup.shthat accepts one input argument that is the name of a filef.

backup.shmakes a copy of the filefand saves it using the name offfollowed by.bak

After copying the file, the script removes write permission for all users on the backup file.

For example:

./backup.sh myfile.txt

copies the filemyfile.txtsaving the copy asmyfile.txt.bakand removes write permission onmyfile.txt.bak

No error checking is required in this question. You can assume that one argument is always given and the filefexists.