Category: English Post (英文帖子)

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Several situations of Linux automatically reboot without reboot logs in the /var/log/messages

Situation One

This Linux server is a virtual server. If we reboot it though its virtual software, there is no relevant logs in the /var/log/messages.

Situation Two

This Linux server is a member of a pacemaker cluster. If the pacemaker cluster software fences this server for protecting the whole cluster, there is no relate logs in the /var/log/messages.

Situation Three

This Linux server has critical problems in its system or hardware. Core panic of Linux and hardware problem both can reboot the system automatically without any reboot logs in the /var/log/messages.

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[CONTENT] System local ports batch occupation

Content One: Occupy system local ports manually

# startport=33000;endport=34000;for i in $(seq $startport $endport);do nc -lk $i &;done

(Add: Take start port is 33000 and end port is 34000 as an example here)

Content Two: Release all ports which are opened manually (kill all nc command processes)

# for i in $(ps -aux | grep nc | grep '\-lk' | awk '{print $2}');do kill $i; done
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[CONTENT] Linux maximum number of processes setting

Case One: Set the maximum number of processes for all users

# vim /etc/security/limits.conf

Add the following

......
* soft nofile 10240
* hard nofile 10240

(Add: Take maximum number of processes is 10240 for everyone as an example here)

Case Two: Set the maximum number of processes for one group

# vim /etc/security/limits.conf

Add the following

......
@mingyuzhu soft nofile 10240
@mingyuzhu hard nofile 10240

(Add: Take maximum number of processes is 10240 for group mingyuzhu as an example here)

Case Two: Set the maximum number of processes for one user

# vim /etc/security/limits.conf

Add the following

......
mingyuzhu soft nofile 10240
mingyuzhu hard nofile 10240

(Add: Take maximum number of processes is 10240 for user mingyuzhu as an example here)