0

I have a program, that runs on only one Raspberry Pi, but could be run from multiple other computers (through SSH).

When I run my program on the Pi, it runs as expected.

To be able to run from crontab or SSH, I created (ok, scissored together) some bash scripts, however, it is not running as intended.

The first was like this: 

exec sudo /usr/bin/java \
-Djava.library.path=/usr/lib/jni \
-cp /usr/share/java/RXTXcomm.jar \
-jar '/home/pi/forgokapu/dist/forgokapu.jar' < /dev/tty1

However, it did not allow to read from the Pi's tty1. (I think that & means to run in the background).

However, even without the &, it gives the output to the computer it's run from (pts/0), but doesn't take input from anywhere. I tried to add 

exec sudo /usr/bin/java \
-Djava.library.path=/usr/lib/jni \
-cp /usr/share/java/RXTXcomm.jar \
-jar '/home/pi/forgokapu/dist/forgokapu.jar' < /dev/tty1 >/dev/tty1

to force both input and output to the tty1, but now the output does not appear anywhere, and ps -A shows it is running on pts/0, not tty1.

The < /dev/tty1 is inside the script, but the program still runs on pts/0 (or crontab), and not taking input from it's tty1. Bash does.

520 tty1 00:00:00 login 
690 tty1 00:00:01 bash 
917 pts/0 00:00:00 bash 
1221 pts/0 00:00:00 sudo 
1227 pts/0 00:00:00 java 
1241 pts/0 00:00:00 ps

</dev/tty1 does not redirect java to tty1.

Question:

How can I force the program to take input from the tty1?

I don't need bash, so it should run in the foreground. Redirection of output is not important, but I would have from the origin of the program start for debugging purposes.

I also tried 0</dev/tty1, but the input is still from pts/0

I also tried 

setsid sh -c 'exec sudo /usr/bin/java \
-Djava.library.path=/usr/lib/jni \
-cp /usr/share/java/RXTXcomm.jar \
-jar "/home/pi/forgokapu/dist/forgokapu.jar" <> /dev/tty1 >&0 2>&1'

from Start a process on a different tty, but it's still not working. :'(

script is also no good, I need the opposite of what it does.

Bart
  • 2,151
  • 1
  • 10
  • 26
kry
  • 113
  • 6
  • was one of the attempts: `program < /dev/tty1` ? That's the simplest, unless the program is deciding for itself what to open? – Jeff Schaller Feb 11 '19 at 13:17
  • Bash should decide. The < /dev/tty1 is inside the script, but the program still runs on pts/0 (or crontab), and not taking input from it's tty1. Bash does. `520 tty1 00:00:00 login` `690 tty1 00:00:01 bash` `917 pts/0 00:00:00 bash` `1221 pts/0 00:00:00 sudo` `1227 pts/0 00:00:00 java` `1241 pts/0 00:00:00 ps` – kry Feb 11 '19 at 13:20
  • You'll need to edit the post to provide clarification -- particularly ones that include formatting (comment formatting is limited). – Jeff Schaller Feb 11 '19 at 13:37
  • Just to check: you're not actually using those parenthesis around the command, are you? Because they are shell syntax for a subshell, and at that point of the command, it'd be invalid syntax. I do also wonder what the meaning of `exec ... &` is, since `exec` replaces the shell, so it can't very well be put in the background – ilkkachu Feb 11 '19 at 13:39
  • No, it just copies a lot of things in the background, so I snipped the actual command. I don't know what & does, I just copied it from an another question. It does not affect the behavior of the Pi, does the same with and without. – kry Feb 11 '19 at 13:40
  • To keep people from getting distracted, it might be more useful to everyone to show the actual command you're using? – Jeff Schaller Feb 11 '19 at 13:44
  • I don't see how that would help, but added it anyway. – kry Feb 11 '19 at 13:47
  • you're sure that the java program itself doesn't open the tty device on its own? – Jeff Schaller Feb 11 '19 at 15:37
  • It reads from the console with `scanner::nextLine()`. – kry Feb 11 '19 at 15:38
  • That `ps` output shows a `login` process on `tty1`, and I suppose you'd usually have something like that there (`login` or `getty`) to be able to log in. How would it work to have both the usual login prompt there, and your program, both reading from the terminal at the same time? What should happen if someone is logged in on that virtual terminal when the command runs? Also, are you sure you want to use `cron` to start a process that reads from the terminal? What if there's no-one there to give any input to it? – ilkkachu Feb 11 '19 at 18:03
  • How should I prevent login, while being able to read from the terminal at the same time? – kry Feb 11 '19 at 20:47
  • https://www.raspberrypi.org/forums/viewtopic.php?t=31567 Is this the one I'm looking for? – kry Feb 11 '19 at 20:51

0 Answers0