XXX#sum utilities, suggested switch

[James E. LaBarre]

I think the "--ignore-missing" option for the checksum validation tools 
(md5sum, sha356sum, etc) needs a short switch.  The great majority of 
the time I am checking checksums, I usually only have one, maybe two of 
the files in the checksum list.  It would seem to me to be a 
higher-priority option.  If there were a way to set this as the 
*default* setting (environment variable?  .config setting?) it would be 
ideal, although I don't know if coreutils works that way.