Programming :: Create/delete Temp/backup Files Through A Shell Script?

I have a shell script that need to create some files:

1) backup files of user passed in file ( that will be written by this shell ).

2) temp files that the shell will create and later delete/remove.

This shell script will be used from my local dir ( I am not a super or a sysadmin ). Users of this shell will call this script to run on their local files in their respective directories. When my script runs, it errors with the following:

cp: cannot create regular file `./listfile.txt.backup': Permission denied
/home/myUser/tools/myShellScript: line 12: listfile.txt: Permission denied

for the temp I was able to avoid this error by creating the temp file in the /tmp directory. All I want is for this shell script to run, create/modify/backup files in user's local dirs.

The user dir has the following permission:

drwxr-xr-x testDir

the file that needs to be backed-up has:

-rw-r--r-- listfile.txt.