From at least V2 to V6, the ls(1) command would not
show directory entries whose names began with a '.'
unless the -a flag was supplied.
This was changed in V7: only the directory entries
for "." and ".." would be skipped by default.
All further versions of Research Unix retain the
convention of V7 and Plan 9 ultimately made it
unnecessary. However, BSD and its descendants did
not follow suit. Instead, they continued behaving
like V6 with an additional -A flag to emulate V7.
Was the initial behavior intentional or just a
matter of expediency?
Who made the change and what was their motivation?
Was it a reaction to the intentional hiding of what
came to be known as "dot files"?
Thanks,
Anthony