One or two dots (. or ..), OK, but what do three or more dots mean?

Question

Why does this work?

if [ -d "." ] ; then echo "ok"; else echo "nok"; fi
if [ -d ".." ] ; then echo "ok"; else echo "nok"; fi
if [ -d "..." ] ; then echo "ok"; else echo "nok"; fi
if [ -d "...." ] ; then echo "ok"; else echo "nok"; fi
if [ -d "nosuchdir" ] ; then echo "ok"; else echo "nok"; fi

Output:

ok
ok
ok
ok
nok

What is supposed to mean ... or .... in a shell env?

Answer 1

这意味着有人创建了名为...和 的目录....。考虑：

$ [ -d '...' ] && echo 'ok' || echo 'nok'
nok
$ mkdir ...
$ [ -d '...' ] && echo 'ok' || echo 'nok'
ok