How can I determine when a serial terminal has (dis)connected?
I have a DEC VT101 serial terminal hooked up to a Raspberry Pi 3 running Debian using a USB RS-232 null modem cable. When I turn the terminal off, I would like for the shell session to end, and when I turn the terminal back on, I'd like that to start a new login session. How can I do this? Right now, when the terminal is turned off then back on, the screen remains blank until I do something e.g. press Return which will make Bash draw a new prompt.
At the very least, if I could figure out how to query whether there was a system receiving the data from the USB null modem cable, I could script the automatic logging in/out myself. One approach I have in mind would be to send answerback queries to the terminal when there has been no recent user input then assume the terminal is off if I don't get a response after a certain amount of time.
shell terminal getty
New contributor
add a comment |
I have a DEC VT101 serial terminal hooked up to a Raspberry Pi 3 running Debian using a USB RS-232 null modem cable. When I turn the terminal off, I would like for the shell session to end, and when I turn the terminal back on, I'd like that to start a new login session. How can I do this? Right now, when the terminal is turned off then back on, the screen remains blank until I do something e.g. press Return which will make Bash draw a new prompt.
At the very least, if I could figure out how to query whether there was a system receiving the data from the USB null modem cable, I could script the automatic logging in/out myself. One approach I have in mind would be to send answerback queries to the terminal when there has been no recent user input then assume the terminal is off if I don't get a response after a certain amount of time.
shell terminal getty
New contributor
add a comment |
I have a DEC VT101 serial terminal hooked up to a Raspberry Pi 3 running Debian using a USB RS-232 null modem cable. When I turn the terminal off, I would like for the shell session to end, and when I turn the terminal back on, I'd like that to start a new login session. How can I do this? Right now, when the terminal is turned off then back on, the screen remains blank until I do something e.g. press Return which will make Bash draw a new prompt.
At the very least, if I could figure out how to query whether there was a system receiving the data from the USB null modem cable, I could script the automatic logging in/out myself. One approach I have in mind would be to send answerback queries to the terminal when there has been no recent user input then assume the terminal is off if I don't get a response after a certain amount of time.
shell terminal getty
New contributor
I have a DEC VT101 serial terminal hooked up to a Raspberry Pi 3 running Debian using a USB RS-232 null modem cable. When I turn the terminal off, I would like for the shell session to end, and when I turn the terminal back on, I'd like that to start a new login session. How can I do this? Right now, when the terminal is turned off then back on, the screen remains blank until I do something e.g. press Return which will make Bash draw a new prompt.
At the very least, if I could figure out how to query whether there was a system receiving the data from the USB null modem cable, I could script the automatic logging in/out myself. One approach I have in mind would be to send answerback queries to the terminal when there has been no recent user input then assume the terminal is off if I don't get a response after a certain amount of time.
shell terminal getty
shell terminal getty
New contributor
New contributor
New contributor
asked 1 min ago
Eric PruittEric Pruitt
1012
1012
New contributor
New contributor
add a comment |
add a comment |
0
active
oldest
votes
Your Answer
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "106"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Eric Pruitt is a new contributor. Be nice, and check out our Code of Conduct.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f498541%2fhow-can-i-determine-when-a-serial-terminal-has-disconnected%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
0
active
oldest
votes
0
active
oldest
votes
active
oldest
votes
active
oldest
votes
Eric Pruitt is a new contributor. Be nice, and check out our Code of Conduct.
Eric Pruitt is a new contributor. Be nice, and check out our Code of Conduct.
Eric Pruitt is a new contributor. Be nice, and check out our Code of Conduct.
Eric Pruitt is a new contributor. Be nice, and check out our Code of Conduct.
Thanks for contributing an answer to Unix & Linux Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f498541%2fhow-can-i-determine-when-a-serial-terminal-has-disconnected%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown