Linux Process in Background - "Stopped" in Jobs

Linux process in background - Stopped in jobs?

In Linux and other Unix systems, a job that is running in the background, but still has its stdin (or std::cin) associated with its controlling terminal (a.k.a. the window it was run in) will be sent a SIGTTIN signal, which by default causes the program to be completely stopped, pending the user bringing it to the foreground (fg %job or similar) to allow input to actually be given to the program. To avoid the program being paused in this way, you can either:

1. Make sure the programs stdin channel is no longer associated with the terminal, by either redirecting it to a file with appropriate contents for the program to input, or to /dev/null if it really doesn't need input - e.g. myprogram < /dev/null &.
2. Exit the terminal after starting the program, which will cause the association with the program's stdin to go away. But this will cause a SIGHUP to be delivered to the program (meaning the input/output channel experienced a "hangup") - this normally causes a program to be terminated, but this can be avoided by using nohup - e.g. nohup myprogram &.

If you are at all interested in capturing the output of the program, this is probably the best option, as it prevents both of the above signals (as well as a couple others), and saves the output for you to look at to determine if there are any issues with the programs execution:

nohup myprogram < /dev/null > ${HOME}/myprogram.log 2>&1 &

background process is always Stopped

Try running with nohup. You can analyse the nohup.out log if it still stops.

nohup script.sh

How can I resume a stopped job in Linux?

The command fg is what you want to use. You can also give it a job number if there are more than one stopped jobs.

How to prevent a background process from being stopped after closing SSH client in Linux

Check out the "nohup" program.

`jobs` command doesn't show any background processes

Based on the problem statement of the question, IMHO I do not see any reason for using background or foreground. All you care is to find a process which is running in background so that you can kill it.

Run ps -ef | grep parameter3 to find processes which has parameter3 in the process name. You can adapt the grep to uniquely identify a process, given you don't have two processes with exactly same process name.

Once you have it, just do kill -9 PID and that process will be killed. So no need for bringing that process to the foreground for killing it.

Hope this helps.

Background job getting stopped

the first line of your script:

/#!/bin/bash 

should actually be:

#!/bin/bash 

I assume this was just a typo when posting your question (but you might want to check that out, just in case). Now, if i replace "command1" with an ls -las, it works for me:

#!/bin/bash

while [ 1 ]; do
ls -las | cut -f 3
sleep 5;
done

notice that i've only changed your "command1" by an ls.

so what is "command1" exactly? your job may be stopped if that "command1" needs stdin input (just one of the cases)

Preventing background process from writing to console

If you have started the process already and want to stop it from printing to stdout, while still keeping it running, you may use:

stty tostop

When you give stty the tostop argument it stops the background processes that try to write to stdout

To enable the process to write again you may use fg.

Original source can be found here

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