Is there a way to add some info about time/date to TTY prompt?

Question

If you have a graphical display manager, you can notice date and time there, but I haven't seen such a thing when it comes to TTY. If I want to check the current time (or date) I have to log in. It's a little bit annoying, especially in the morning. :)

I know that I can add the two parameters \t and \d to /etc/issue file, for time and date respectively, but this solution doesn't refresh the time.

I thought maybe there's a way to add a script to the /etc/issue , but I couldn't find anything useful.

Is there a way to add time/date to the prompt?

Answer 1

Idea #1 - Customizing agetty

This is just a rough idea but I believe if your system is making use of systemd then your login prompt is controlled by this service file:

/lib/systemd/system/[email protected]

If you look through this file:

$ grep -i exec /lib/systemd/system/[email protected] 
ExecStart=-/sbin/agetty --noclear %I 38400 linux

If you take a look at agetty's man page it takes variety of switches. Perhaps you could either customize the prompt that agetty shows or you could swap out agetty for an alternative that does, or wrap agetty with a script that would display the time/date.

EDIT #1

Q: I checked agetty man, but there's no info as to displaying time/date in real time.

This wasn't meant as a out of the box solution, it was a rough idea for doing something. In searching for this there isn't really any way to do what you want, easily. You'll have to either create a customized version of agetty or change to something else like mgetty or something else entirely.

Idea #2 - /etc/issue file

The only other method I can conceive of doing something like you want with the time/date being displayed would be to make use of the file /etc/issue. The contents of this file allows for a few macros to be displayed such as these:

excerpt agetty man page

ISSUE ESCAPES
       The issue-file (/etc/issue or the file set with the -f option) may 
       contain certain escape codes to display the system name, date  and
       time etc. All escape codes consist of a backslash (\) immediately 
       followed by one of the letters explained below.

       d      Insert the current date.
       s      Insert the system name, the name of the operating system.
              Same as `uname -s'.
       m      Insert the architecture identifier of the machine. Same as 
              `uname -m'.
       n      Insert the nodename of the machine, also known as the 
              hostname. Same as `uname -n'.

       o      Insert the NIS domainname of the machine. Same as 
              `hostname -d'.
       r      Insert the release number of the OS. Same as `uname -r'.
       t      Insert the current time.

       Example: On my system, the following /etc/issue file:

              This is \n.\o (\s \m \r) \t

       displays as

              This is thingol.orcan.dk (Linux i386 1.1.9) 18:29:30

Here's an example of my ancient /etc/issue box from a Fedora Core 3 system, when I used to take he time to set things like this up.

                         

The source of that file looks like this:

                                

The penguin was generated using the linux_logo command, specifically the classic (-c) version.

Answer 2

You can change the prompt in shells by setting the variable PS1

bash allows several predefined identifiers \d adds the date, and \D{FORMAT} adds time with format. example \D{%H:%M:%S} will print the time (hours mins seconds).

It is worth checking what your current prompt is set to and set it just by hand until you are satisfied, then update your .bashrc file which is what sets it up on my system (Ubuntu).

To see what your current PS1

echo $PS1

To set it

PS1='\u@\h:\w \D{%H:%M:%S} \$ '