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New page

Serial Console HowTo

== Overview ==
Sometimes it is handy to be able to redirect a TTY Console to a serial port.
One such example might be that your server is headless (No VGA, Keyboard, or Monitor)
The info on this page will help you enable console access via a serial port.

== Instructions ==

To redirect a Linux Console to a serial port edit /etc/inittab

6:12345:respawn /usr/sbin/agetty -hL ttyS0 38400 vt100

When done issue this command to make the changes take effect:

init q

''NOTE: There will most likely already be a 6:12345, if that is the case comment out the old 6:12345 with a # like this #6:12345.
I prefer to redirect TTY6 so that if I do login locally TTY1 (the default console) is available.''

== Explanation ==

TTY-ID:RUN-LEVELS:respawn COMMAND -SWITCHES PORT TERMINAL-EMULATION

(For greater detail on inittab or agetty see the references section)

== General Notes ==
1) In this HowTo I used 'agetty' but there are other getty packages, if you use one of the other getty packages keep in mind that the syntax will most likely be different.

== References ==

Linux Serial Console HowTo: [http://www.vanemery.com/Linux/Serial/serial-console.html]

Linux Journal - Serial as a Console: [http://www.linuxjournal.com/article/2040]

inittab Man Pages: [http://www.netadmintools.com/html/5inittab.man.html]

agetty Man Pages: [http://www.netadmintools.com/html/8agetty.man.html]

[[Category:Linux]]

@@ Line 33: / Line 33: @@
 ==Modern Distros using Systemd==
-If you're on an distro that uses systemd, here is another method (in this case Ubuntu 22.04):
+If you're on a distro that uses systemd, here is another method (in this case Ubuntu 22.04):
   cat <<EOF > /lib/systemd/system/ttyS0.service

@@ Line 58: / Line 58: @@
 [http://www.linuxjournal.com/article/2040 Linux Journal - Serial as a Console]<br>
 [http://www.netadmintools.com/html/5inittab.man.html inittab Man Pages]<br>
-[http://www.netadmintools.com/html/8agetty.man.html agetty Man Pages]<br>
+[http://www.netadmintools.com/html/8agetty.man.html agetty Man Pages]
 <br>
 [https://ubuntuforums.org/showthread.php?t=2343595 Serial Console connection on Ubuntu 16.04 or higher]

@@ Line 60: / Line 60: @@
 [http://www.netadmintools.com/html/8agetty.man.html agetty Man Pages]<br>
 <br>
-[https://ubuntuforums.org/showthread.php?t=2343595]
+[https://ubuntuforums.org/showthread.php?t=2343595 Serial Console connection on Ubuntu 16.04 or higher]

@@ Line 29: / Line 29: @@
 ) In this HowTo I used 'agetty' but there are other getty packages such as 'getty', 'mgetty', and 'mingetty' use whichever is the default on your distribution. If you use one of the other getty packages keep in mind that the syntax will most likely be different.<br>
 ) ttyS0 = COM1, ttyS1 = COM2 etc...
@@ Line 36: / Line 59: @@
 [http://www.netadmintools.com/html/5inittab.man.html inittab Man Pages]<br>
 [http://www.netadmintools.com/html/8agetty.man.html agetty Man Pages]<br>

@@ Line 27: / Line 27: @@
 == General Notes ==
-) There will most likely already be a 6:12345, if that is the case comment out the old 6:12345 with a # like this #6:12345.<br>
+) In this HowTo I used 'agetty' but there are other getty packages such as 'getty', 'mgetty', and 'mingetty' use whichever is the default on your distribution. If you use one of the other getty packages keep in mind that the syntax will most likely be different.<br>
-) In this HowTo I used 'agetty' but there are other getty packages such as 'getty', 'mgetty', and 'mingetty' use whichever is the default on your distribution. If you use one of the other getty packages keep in mind that the syntax will most likely be different.<br>
+) ttyS0 = COM1, ttyS1 = COM2 etc...
-) ttyS0 = COM1, ttyS1 = COM2 etc...

@@ Line 10: / Line 10: @@
 == Instructions ==
-To redirect a Linux Console to a serial port edit /etc/inittab
+To redirect a Linux Console to a serial port edit /etc/inittab and add this line at the end of the '# Run gettys in standard runlevels' section.
-:12345:respawn /usr/sbin/agetty -hL ttyS0 38400 vt100
+  S0:2345:respawn /usr/sbin/agetty -h ttyS0 38400 vt100
 When done issue this command to make the changes take effect:
@@ Line 28: / Line 28: @@
 == General Notes ==
 ) There will most likely already be a 6:12345, if that is the case comment out the old 6:12345 with a # like this #6:12345.<br>
-) I prefer to redirect TTY6 so that if I do login locally TTY1 (the default console) is available.<br>
+) In this HowTo I used 'agetty' but there are other getty packages such as 'getty', 'mgetty', and 'mingetty' use whichever is the default on your distribution. If you use one of the other getty packages keep in mind that the syntax will most likely be different.<br>
-) In this HowTo I used 'agetty' but there are other getty packages such as 'getty', 'mgetty', and 'mingetty' use whichever is the default on your distribution. If you use one of the other getty packages keep in mind that the syntax will most likely be different.<br>
+) ttyS0 = COM1, ttyS1 = COM2 etc...
-−

@@ Line 5: / Line 5: @@
 One such example might be that your server is headless (No VGA, Keyboard, or Monitor)
 The info on this page will help you enable console access via a serial port.
@@ Line 17: / Line 18: @@
   init q
 == Explanation ==
 TTY-ID:RUN-LEVELS:respawn COMMAND -SWITCHES PORT TERMINAL-EMULATION
 == General Notes ==
-) In this HowTo I used 'agetty' but there are other getty packages, if you use one of the other getty packages keep in mind that the syntax will most likely be different.
+) There will most likely already be a 6:12345, if that is the case comment out the old 6:12345 with a # like this #6:12345.
 == References ==
+[http://www.vanemery.com/Linux/Serial/serial-console.html Linux Serial Console HowTo]
+[http://www.linuxjournal.com/article/2040 Linux Journal - Serial as a Console]
-Linux Serial Console HowTo: [http://www.vanemery.com/Linux/Serial/serial-console.html]
+[http://www.netadmintools.com/html/5inittab.man.html inittab Man Pages]
+[http://www.netadmintools.com/html/8agetty.man.html agetty Man Pages]
-Linux Journal - Serial as a Console: [http://www.linuxjournal.com/article/2040]
-−
-inittab Man Pages: [http://www.netadmintools.com/html/5inittab.man.html]
-−
-agetty Man Pages: [http://www.netadmintools.com/html/8agetty.man.html]