I am using Debian stretch (systemd).
I was running the rsyslog daemon in foreground using
/usr/sbin/rsyslogd -n
and I did a Ctrl+Z to stop it.
The state of the process changed to Tl (stopped, threaded).
I issued multiple kill -15 <pid> commands to the process, and the state of the process was the same: Tl. Once I did an fg, it died. I have 3 questions.
Linux doesn’t actually distinguish between processes and threads, and implements both as a data structure task_struct.
I have access to an 8-core node of a Linux cluster. When logged in to the node, I can see a list of processors using this command:
What is the rationale behind making I/O uninterruptible? What would be the negative consequences if a process handling I/O were allowed to handle a signal?
I don’t understand iotop output: it shows ~1.5 MB/s of disk write (top right), but all programs have 0.00 B/s. Why?
Why does /proc/pid/maps contain a few records for the same library ? Here is an example:
I’m writing a script which will use the filename of running processes. However, I’m unable to determine the full executable name of some processes.
We have a script which runs on our web servers, triggered by customer action, which initiates a unix process to generate some cache files. Because this process acts upon files supplied by our customer, it sometimes misbehaves, running so long that the PHP process which spawns it times out or using so much CPU time that a sysadmin will kill it.
From the question here, the OP wants to repeatedly poll the pid of a process using pidof in a shell script. Of course this is inefficient as a new process must be started for the pidof program multiple times per second (I don’t know that this is the cause of the CPU spikes in the question, but it seems likely).
I have a process that gets started by a damon running as root, now I want to “downgrade” this process’s privileges to those of your average user. Is this possible? If yes how?