I want to add files to an iso. The iso is large, and I'm on Linux.
To add files to an ISO on Linux, you can use the genisoimage or mkisofs command-line tools. Here's how to do it:

1. Install the genisoimage package if it's not already installed on your system. You can do this by running the following command in a terminal:
``` 
sudo apt-get install genisoimage
``` 
2. Create a directory for the files you want to add to the ISO. For example, you could create a directory called iso_files in your home directory:
``` 
mkdir ~/iso_files
``` 
3. Copy the files you want to add to the ISO into the iso_files directory.

4. Use the genisoimage command to create a new ISO image that includes the files in the iso_files directory:
``` 
genisoimage -o /path/to/new_iso.iso -r -J ~/iso_files
``` 
In this command, replace /path/to/new_iso.iso with the path and filename you want to use for the new ISO image. The -r and -J options specify that the ISO should use the Rock Ridge and Joliet extensions, which allow long filenames and other features not supported by the basic ISO 9660 format.

5. Wait for the genisoimage command to finish. This may take a while, especially if you're adding a lot of files to the ISO.

6. Once the command finishes, you should have a new ISO file that includes the files you added. You can verify this by mounting the ISO and checking that the files are present:
``` 
sudo mount /path/to/new_iso.iso /mnt/iso
ls /mnt/iso
sudo umount /mnt/iso
``` 
In this command, replace /path/to/new_iso.iso with the path and filename you used for the new ISO image. The mount command mounts the ISO at /mnt/iso, and the ls command shows the files in the mounted ISO. The umount command unmounts the ISO when you're done.
Create a shell script for this, please. But:
```
/path/to/new_iso.iso = /tmp/sillywilly.iso
```