21.9 Reading a Password

To read a password to pass to another program, you can use the function read-passwd.

Function: read-passwd prompt &optional confirm default ¶

This function reads a password, prompting with prompt. It does not echo the password as the user types it; instead, it echoes ‘*’ for each character in the password. If you want to apply another character to hide the password, let-bind the variable read-hide-char with that character.

The optional argument confirm, if non-nil, says to read the password twice and insist it must be the same both times. If it isn’t the same, the user has to type it over and over until the last two times match.

The optional argument default specifies the default password to return if the user enters empty input. If default is nil, then read-passwd returns the null string in that case.

This function uses read-passwd-mode, a minor mode. It binds two keys in the minbuffer: C-u (delete-minibuffer-contents) deletes the password, and TAB (read-passwd--toggle-visibility) toggles the visibility of the password. There is also an additional icon in the mode-line’s global-mode-string. Clicking on this icon with mouse-1 toggles the visibility of the password as well.