I have a program running on armbian single board computer. The program starts with -b option during the startup of the system. I created this simple shell script
#!/bin/bash
#Myprog server start
sudo -b /home/myprog/myprog
This program is C written and it sometimes outputs some information with printf functions. But since it is started with -b option there's is noting in the console.
Now when I log in to the armbian via ssh with Putty I want to occasionally read the output of this program. Is it even possible?
Not exactly what you’re asking, but generally speaking it’s better practice to redirect output to a log file than to try to interactively look at the console output for a background app.
Something like:
sudo -b /home/prog/myprog >> /home/prog/log.txt 2>&1
Should do it.
Then view output with
tail -f /home/prog/log.txt
If it’s really important to you to run interactively without logs, I would suggest running it from within “screen” without backgrounding it.
screen
sudo /home/prog/myprog
Then ctrl-d to detach and let it run in background. screen -r to reattach.
Related
I am working on a moon rover for Carnegie Mellon University which will be launching next year. Specifically, I am working on a flight computer called the ISIS OBC (On Board Computer) and I am trying to find out how to first run QEMU in a terminal in the background, and then run GDB to connect to the QEMU instance I just backgrounded. I have tried running QEMU in the background with & as well as using the flag -daemonize but this causes QEMU's GDB server to not work at all.
The overarching goal is to be able to debug our flight software in GDB in one terminal window so that I can run it from inside a Docker container mounted on the repository's root. It takes a bit of setup to get be able to debug our code, with a couple of gotchas like incompatibility with newer versions of GCC, so being able to run the CODE and debug it from inside a Docker container (which has all our other development dependencies installed too) is a must.
My current solution was to just run QEMU in another gnome-terminal I initialized in the startup script completely outside of the docker container, but this will not work in Docker for obvious reasons. Here is that code in case the additional context is helpful:
#!/bin/bash
#The goal of the below code is to get the stdout from QEMU piped into GDB.
#Unfourtunately it appears that QEMU must be started as the FG in its own window so that it will
#start its GDB server, so an additional window is required.
my_tty=$(tty)
gnome-terminal -- bash -c './../obc-emulation-resources/obc-qemu/iobc-loader -f sdram build/app.isis-obc-rtos.bin -s sdram -o pmc-mclk -- -serial stdio -monitor none -s -S > /tmp/qemu-gdb; $SHELL' --name="QEMU-iOBC" --title="QEMU-iOBC" -p
tail -f /tmp/qemu-gdb > $my_tty&
./third_party/gcc-arm-none-eabi-10.3-2021.07/bin/arm-none-eabi-gdb -ex='target remote localhost:1234' -ex='symbol-file build/isis-obc-rtos.elf'
# Kill any leftover qemu debugging sessions
kill $(ps aux | grep '[i]obc-loader' | awk '{print $2}')
# Delete intermediate file
rm -f /tmp/qemu-gdb
# Get's rid of any extra text that may occur
echo ""
clear
I would much prefer to run something like this to achieve my goal:
./../obc-emulation-resources/obc-qemu/iobc-loader -f sdram build/app.isis-obc-rtos.bin -s sdram -o pmc-mclk -- -serial stdio -monitor none -s -S > /tmp/qemu-gdb
rather than what I am running now:
gnome-terminal -- bash -c './../obc-emulation-resources/obc-qemu/iobc-loader -f sdram build/app.isis-obc-rtos.bin -s sdram -o pmc-mclk -- -serial stdio -monitor none -s -S > /tmp/qemu-gdb; $SHELL' --name="QEMU-iOBC" --title="QEMU-iOBC" -p
"iobc-loader" is a wrapper used to run the QEMU command by the way."app.isis-obc-rtos.bin" is of course the binary I am trying to run and "isis-obc-rtos.elf" contains the symbols used to debug it. Apologies if the answer is obvious, I am a student!
You can try using a terminal multiplexer like screen or tmux, which allow you to run each command in foreground in a separate virtual terminal.
You can also create panes, for example with tmux press Ctrl+b " to split the screen horizontally or Ctrl+b % to split it vertically, then Ctrl+b o to cycle between them.
Using tmux is definitely the easiest approach, especially with its built in CLI support.
You could write a script similar to this one:
tmux start-server
tmux new-session -d -s debug-session -n isis -d "<cmd1>";"<cmd2>"
Where cmd1 is your QEMU execution script, and cmd2 is another script that runs the docker you want to use for debugging.
I'm writing script to run iperf on linux device accessible via adb.
From a terminal, when I run the command: adb shell iperf -c ......
I get the log of the command 50 s after the command starting.
inconvenient: during 50 s you are not sure that iperf has started
I tried the logcat command (logcat --pid ...), It gives the same result.
From a terminal, when I enter adb session first and then I run the command: iperf -c .....
I get the log of the command in real time.
inconvenient: I'm not able to automate the procedure, because I have to start the adb session first
For the first use case: Is there a way to force "log flush" in order to get the log in real time?
For the second use case: Is there a way to send commands to already opened adb shell session?
Is there any other ways to launch iperf on device and get the log in real time?
The solution i found is the library pexpect that allow to interact with adb session.
I'm using a psuedo terminal, /bin/sh -i, by calling normal commands for posix_openpty() then fork(), in language C.
When I run from command line GUI terminal like this
$ ./MyTerminal
or
$ sudo ./MyTerminal
or as root like this
# ./MyTerminal
all works very good and as expected, no problems.
However, when I make a systemd service file like this, it works fine
[Service]
User=root
But when I try to get systemd to run it as normal user like this
[Service]
User=debian
THe first output for /bin/sh -i is
/bin/sh: 0: can't access tty; job control turned off $
And the terminal does not really work.
When I run /bin/bash, fork() w/posix_openpty() is returns me this, but the terminal generally works ok
bash: cannot set terminal process group (-1): Inappropriate ioctl for device
bash: no job control in this shell
Is such a weird prolem because when running outside of systemd everything works perfect. I see this problem in 1 other question but no clear solution. So what I have to change to make systemd run my file perfectly? Thanks for your help.
I am using windows XP operating system and cygwin is installed in my C drive.
I need to login to cygwin directly to my directory path which contains a makefile and also a bash script called build.sh in the same directory. So i modified the original cygwin.bat file and added the line as shown below.
#echo off
C:
chdir C:\cygwin\bin
bash --login "/cygdrive/E/scheme_31july/build/build.sh"
When i double click on this bat file i could see my script executing but not on cygwin shell but on windows cmd shell as a result I get errors for "make" command like "No rule to make target" as make comes bundled with cygwin.
And when I explicitly login to cygwin using default cygwin.bat file and execute my script by giving following commands in cygwin shell the script executes without errors.
Basically I want to write a bat file so that I can keep it anywhere in my PC and instead of manually openeing the cygwin prompt and typing commands like:
$ cd /cygdrive/E/scheme_31july/build/
$ sh build.sh
it should happen automatically. I sit possible to do so.
Regards,
Harshit
No rule to make target sounds more like make being executed in the wrong directory. make itself seems to be available and running as intended.
Try this:
bash --login -c "cd /cygdrive/E/scheme_31july/build/ && sh build.sh"
This should start a --login session (which should give you access to all the settings and tools you'd expect in a cygwin prompt environment), then execute the given shell command, which is the cd and sh you asked for. You could also write those two lines to a separate script file, and pass the name of that to bash instead of the full path to build.sh.
You could also try to cd into C:\scheme_31july\build in the bat file and then execute bash from there. Not sure whether bash will try to change path upon entering the login session. You can try whether things work without the --login, both for this approach and the one above.
#echo off
C:
cd C:\scheme_31july\build
C:\cygwin\bin\bash.exe ./build.sh
I'm not sure whether you want the session to turn interactive after that or not. In the above case, bash will terminate after the script completed, and might even close the window. You might have to add a read into build.sh to avoid that. If you want bash to turn interactive after executing some command, you can try using the --rcfile option of bash to execute some commands and then turn interactive.
I have been trying to automate this process in shell script in a unix box. I am new to shell scripts.
I have not been able to figure out how to detect when the startup for it has finished . Also, how to
create a new terminal and check the domain.log for the new terminal. I would appreciate if anyone
can help me on this .
cd $/home/oracle/12/bin
./lsnrctl start
Login to sqlplus with username sys as sysdba and password: oracle3211
and run the database startup command startup
Once it is started type exit
--now start the dbconsole
cd $/home/oracle/12/bin
./emctl start dbconsole
--open a new terminal and execute this
$/home/oracle/startWeblogic.sh
--wait for domain.log keyword in the log file to confirm the server has started
--if the server is started proceed to the following in a new terminal
$/home/oracle/startManagedWeblogic.sh
--after this access the following urls
https://178:198:29:28:1167/em (username=system1, password=oracle123)
https://178:198:29:28:1176/em (username=system2, password=oracle132)
Sounds like you also need to learn about the GNU screen command. You may already have it installed. Try screen -R -D
If it gives you a shell prompt at the top of the screen then it works. Now if you disconnect your ssh session or close your terminal window (click on the X), the next time you log in and run the exact same screen command, you are reconnected to the same running terminal session.
This allows you to run scripts, etc. which do not stop when you disconnect. And when you reconnect you can see their current output.
Also, you can have many terminal sessions. Ctrl-A c creates another one. Ctrl-A [space] and Ctrl-A [backspace] rotate between sessions in the list. Ctrl-A ? gives you all the other Ctrl-A commands that you can use. For instance, one session could be tail logfile while another one is running a program waiting for input.