Stuart,
From your output below it looks like md5sum was executed as you have
the 
an error reported by md5sum.
It looks like md5sum is complaining about not being able to see the file
pcl.iso. Also there is a permissions problem with somthing the script is
trying to call. Not sure what is going on with that bit to be honest as
you have run the script as root, unless it needs to have write permissions
which of course you won't have on a cdrom.
If use the type command it should confirm if you have the md5sum binary in
your path - try `type md5sum` if found you should see something like
'md5sum is hashed /usr/sbin/md5sum' if not it will say not found.
Hope this helps
Mark
 Mark,
 DVD came with a mag.
 The command is their published instruction.
 This is what I get.
 Baffled
 Stuart
 Password:
 [root@localhost stuart]# sh /mnt/cdrom/Distros/PCLinuxOS/mkiso
 Creating pcl.iso
 /mnt/cdrom/Distros/PCLinuxOS/mkiso: line 42:
 ../../Essentials/Jigdo/jigdo-file: Permission denied
 ISO image written to /home/stuart//pcl.iso
 Verifying MD5 checksums...
 md5sum: pcl.iso: No such file or directory
 pcl.iso: FAILED open or read
 md5sum: WARNING: 1 of 1 listed file could not be read
 Verification failed, or you do not have the md5sum program installed.
 In the latter case, you probably have nothing to worry about.
 [root@localhost stuart]# cd /home/stuart//pcl.iso
 bash: cd: /home/stuart//pcl.iso: No such file or directory
 [root@localhost stuart]#