"at" command help

marlor · 08-08-2004, 12:45 AM

hi everyone,

for the ones who don't knwo "at" it's something like cron which executes a job at a certain time.

well cron is more for automating jobs, at is more for one timer job, e.g you want to echo on your tty1 "hey it's time for beer" at 18:00

i can do that:

Code:

at 18:00
at> echo "hey it's time for beer" 1> /dev/tty1

what i cannot do is to launch a program in the specified tty, i got help before but it works partialy:

Code:

at 18:00
at> export TERM=linux
at> pico 1> /dev/tty1

this code pops up pico on tty1 at 18:00 but it just displays it and it is not useable, try it yourself you will know what i mean.

QUESTION:
any suggestions how to launch a program in a useable way?

thanks in advance

Hko · 08-08-2004, 05:50 AM

This is impossible, or at least quite hard to realize.
Reason is that "at" works by having a daemon running in the background (the at-daemon, call "atd"). One of the most important features of a daemon is that it detaches itself from any terminal, and ensure it will never be able to get a terminal ever again. So all stuff started by "atd" will not have a terminal either. And this is exactly what "at" is meant to do: running program unattended, in the background,without needing a terminal.

The only way I can think of doing this with "at" is this:
Make and "at" job that starts a tty process on a free virtual terminal, like the "login" program does, (which is started at boot time by "init"). Then have that tty switch UID and start "pine".

This way it will run on a new virtual terminal, not one already running. This is probably not what you want. And you need to write some non-trivial program in C (or similar) to do the stuff described above. And have at run it as root.

Cedrik · 08-08-2004, 06:06 AM

any suggestions how to launch a program in a useable way?

As Hko said, you can lauch every program that does not depend of a terminal, like most of X programs

marlor · 08-08-2004, 06:10 AM

i'll be starting C,C++,java this semester in uni so i'll have to wait for that one

Cedrik · 08-08-2004, 06:12 AM

Now that I 'm thinking, why don't you use something like this :

sleep 120 && pico

marlor · 08-08-2004, 06:33 AM

yes thanks that seems to be a good alternative which i didn't think of but is it possible to send the "sleep" to background and when it's time display pico in forground as normal?

something like:

sleep 100&; pico
or
sleep 100& && pico
or
sleep 100 && pico& (well this one also sends pico to the bg)

well the above don't work, either not what i was hoping for, or i get syntax error
is there a way to tacle this?