I have triggered a Unix script which is basically put details from DB and create a xml for many id's(approximately 1000 items). After generating all XML it will post it to a queue. Right now I have doubt. My Script is running in a script. I am just monitoring it using PUTTY. will my script continuing executing if I shut down my system?
As Barmar's comment suggests, you should first start a screen session by typing screen in the shell.
Next, you should start your script.
Finally, you should disconnect your screen session and log out, with Control-a, d.
Whenever you login again, if you want to see the progress, you can do screen -a to reattach the screen.
If you executed your script in the foreground (or forked it to the background with &), it will terminate once your session closes.
To avoid this, you have a few alternatives:
Use nohup with & to force the program to ignore the SIGHUP signal.
Use a scheduler like cron, at, or your init system to schedule the process to run at/for a certain amount of time.
Use a virtual terminal multiplexer like GNU screen or tmux to run the program in the "background" on a resumable terminal.
Using a scheduler is probably the most versatile of the three, but a multiplexer can be useful if you'd like to see the script's output in real time.
Related
I am working with a log analytics tool called Splunk, which executes a Powershell script and stores the output.
The script execution takes pretty long time and the output is around 100MB+ when the script completes the execution.
When I check the log of the script, I found out that the execution was paused and continued after around an hour!
After looking at the question about QuickEdit mode of the Powershell console metioned here, There are 2 possible reasons why this can happen:
If the QuickEdit mode of the Powershell console is On, and if there are any selected words or area in terminal. But, this is not the case, as the Powershell is invoked as a background process
If the stdout throughput is too much than the host console can handle. Possible reason as the output of the script is very large as mentioned.
Note: there is no sleep or stdin expected in the powershell script as it is meant for collecting performance metrics.
What is the exact reason of the hang of the process in this case, (from 2 mentioned about or any other) and how can I prevent it?
I have my own embedded Linux system on PocketBeagle board. I have developed a simple gpio application in C that issues an on/off command to one of the pins of the connectors of the board. The application is called gpio_aa6 and located at /root.
The first challenge was to find a way to launch my application automatically after booting the board. I found two ways to do that; the first was to add an entry to etc/rcS directory. This entry is a simple script file that launches my application. The second way was to edit /etc/inittab file and add an entry to that file (::respawn:/root/gpio_aa6). In both these ways my application was launched successfully: but I am still not sure if this is the right way to launch my application automatically.
Then I came to the second challenge, how can I stop my running application, as the respawn re-launches the application if it's terminated?
I am communicating with the board in two ways; via a serial communication (using screen terminal) and via web sever (root#192.168.42.2). I have tried to use Ctrl+C, Ctrl+Z, Ctrl+\, but couldn't stop the program from being continue running. Then I used command "killall" with killsignals -9 or -15, it seems that the program is interrupted but it's launched again directly after that.
My application is to run infinitely, but I need to stop it sometimes to update it and re-launch it again.
Is there any suggestion how to overcome this problem?
Thanks.
Both solutions you have used are correct. I personally prefer the option of adding an init script to /etc/init.d though.
I believe the behavior that you observe that you apparently can't kill the program is because you are starting your program from inittab, with the respawn keyword, which precisely tells the init program to restart your application when it exits. If you actually check the PID of your application, you will see that it changes everytime you kill it.
Therefore, I would recommend you to use an init script instead, with which you can implement start and stop actions. See ./package/lldpd/S60lldpd for a basic example in Buildroot.
I have a C program which spawns a pthread to act as an interactive terminal: reading lines from stdin & acting upon them. The program acts as a kind of shell, fork-ing off processes; each process so created has its stdin re-directed using a call to freopen() before using exec to load the new executable.
Before the interactive thread is started, all works fine. Once it has started (or, more specifically, whenever it is waiting for input), calls to freopen() hang. Is there some way to avoid this problem?
The solution that is working for me can be found in R.'s answer to Is close/fclose on stdin guaranteed to be correct?
Basically, the idea is to open the file you want to redirect to, duplicate that to stdin, and then close the file description just opened.
We have some Batch scripts (.bat) in Windows to execute the “backups” and “archive log” for the databases. These scripts are called from Tivoli periodically.
For each executed script, the process creates a sub session in order to load the DB2cmd environment, in order to execute the db2 commands and exit.
daily.bat
call db2cmd hourly.cmd
The content of the script is this:
db2_job_saveddaily.cmd
db2 -fE:\DB2\scripts\tmp\db2_job_savedbhourly.db2 -zE:\DB2\scripts\tmp\db2_job_savedbhourly.log
exit
The content of the db2 file is (however, it is not important because it is executed correctly)
db2_job_saveddaily.db2
archive log for database ICMNLSDB
We are facing a problem with these scripts, and I think it is related with the exit. At one execution, the script freezes, and it starts to consume the whole CPU (see attached image). After this behavior, we cannot execute any other DB2 command from the CLP.
We kill all the CMD.exe and db2bp.exe processes, but the error persists.
There is nothing in the db2diag.log file, and the only solution is to restart the machine.
Probably, the CMD.exe process losses the communication with the db2bp.exe, and the exit cannot be executed. I would like to understand the origin of this problem and learn how to execute db2 processes in Windows.
Our friend #AngocA seems to check into SO often but hasn't been checking this dangling question even though he did something to close it. Let's at least put his answer in here so folk know it's CLOSED by user. :) Courtesy of tonight's Point Pimp. :-D
"The problem was in another db2cmd session where there was an
infinitive loop. This created a scenario when new db2cmd session
blocked because the first session used the whole CPU. – AngocA"
I would like to run a shell script from my cocoa app when clicking on a button. I can easily use the system() call to do that, but that's not all i need. I need the app to close as soon as it calls the script, or even before it calls the script. Basically the script should take a few seconds to run so i need the app to close by that time. The reason i need this is because i'm writing a simple application that puts the mac to sleep, but before that it does lots of cleaning up via a shell script and i basically don't want this app to be open when i brind the system back from sleep.
Would using a fork or something like that do the job or do i need some special magic to do this?
Thank you
If you're in Cocoa, you'll want to use NSTask. If your script needs admin privileges, there's always STPrivilegedTask.
You can use popen() instead of system(). The init process should inherit ownership of the script you run once your application exits. You could also fork/exec, but popen will be simpler as its semantics are much closer to that of system().