linux - How do I find help for point command `.` in *nix?

I need to find help for point command . such as in . ./my_script.sh (I mean the first point.)

I have already tried to find a man page using man . and man \.. How can I display a man page in which it explains the use of command .?

Answer

First of all you should invoke type ., you will probably get something like:

. is a shell builtin

Builtins are parts of your shell, they don't have their own manual pages. Some of them may seem to have them though, e.g. echo is a builtin in Bash but most likely there is a separate executable like /bin/echo in your system and in this case man echo refers to the latter. These two echos are probably not strictly equivalent.

Your shell may provide information about any builtin via help builtin; try help help, help type and finally:

help .

Builtins may also be listed in your shell's manual page. E.g. (in my Debian) Bash builtins are covered directly in man bash, yet for Zsh builtins man zsh tells me to run man zshbuiltins. In general shells may or may not explain their builtins.