function displays a prompt to, and reads in a password from,
If this file is not accessible,
displays the prompt on the standard error output and reads from the standard
The password may be up to
(currently 128, as defined in the
characters in length.
characters and the terminating newline character are discarded.
turns off character echoing while reading the password.
The calling process should zero the password as soon as possible to
avoid leaving the cleartext password visible in the process's address
Upon successful completion,
returns a pointer to a NUL-terminated string of at most
If an error is encountered, the terminal state is restored and
a null pointer is returned.
function was interrupted by a signal.
The process is a member of a background process attempting to read
from its controlling terminal, the process is ignoring or blocking
the SIGTTIN signal or the process group is orphaned.
The process has already reached its limit for open file descriptors.