Mount ISO and alternate disk formats in macOS

Make a folder mount point:

mkdir mount-folder

Use hdiutil to attach the ISO without mounting it:

hdiutil attach -nomount linux.iso
/dev/disk2              FDisk_partition_scheme          
/dev/disk2s2            0xEF

Then use mount to specify a specific format you want to use to mount the disk. This example is using the CD-ROM format:

mount -t cd9660 /dev/disk2 mount-folder