login-prompt — simple chain-load getty for prompting before login
login-prompt
{next-prog
}
login-prompt is a chain-loading utility that prompts to standard output, waits for standard input to have data ready, flushes standard input with the tcflush(3) function, and then (if successful) chain loads to next-prog
with the execvp(3) function.
next-prog
may contain its own command line options, which login-prompt will ignore.
This program is primarily used in TTY login services, but is only necessary therein if next-prog
has timeout functionality that cannot be switched off, as is the case for FreeBSD /usr/bin/login
.
login-prompt effectively delays running that program, and commencing the timeout, until the user has responded to a prompt.
This prevents login processes that timeout from continually respawning on unused terminals.
This can be used as a means to defer running a login program until a user has actually presssed Enter on a terminal.
login-prompt expects the terminal and the line discipline to be in relatively sane states. To reset to these states, run vc-reset-tty(1) or reset(1) before login-prompt.