Question

I want to know more about how CVS login and logout work. Do they create/delete any file? if yes, which are those files? I could not find anything under CVS folders. Are these commands only valid for pserver mode?

Answer 1

This is explained in the CVS documentation, which should also be available via info cvs on your system:

The records are stored, by default, in the file ‘$HOME/.cvspass’. That
file’s format is human-readable, and to a degree human-editable, but
note that the passwords are not stored in cleartext—they are trivially
encoded to protect them from “innocent” compromise (i.e., inadvertent
viewing by a system administrator or other non-malicious person).

You can change the default location of this file by setting the
CVS_PASSFILE environment variable. If you use this variable, make
sure you set it before cvs login is run. If you were to set it after
running cvs login, then later CVS commands would be unable to look
up the password for transmission to the server.

[…]

The password for a given remote repository can be removed from the
CVS_PASSFILE by using the cvs logout command.