Difference between revisions of "CentOS8 CheatSheet fuer System Administratoren"
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cp -av /var/tmp/sosreport* /root/ | cp -av /var/tmp/sosreport* /root/ | ||
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* Show hardware details | * Show hardware details | ||
lshw | lshw | ||
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lsblk | lsblk | ||
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==Memory== | ==Memory== |
Revision as of 15:46, 11 December 2020
Contents
1 SOS Report (Log Bundle)
This collects a log bundle which can be used for later debugging and analyzing.
Start this BEFORE you try to repair or change something, as well do not forget to snapshot/backup System/Application before debugging.
dnf -y install sos sosreport cp -av /var/tmp/sosreport* /root/
2 System
- Show hardware details
lshw
- show bios hardware details
dmidecode
2.1 Disk
- Show block uage of mounted disks
df -hP
- Show inode uage of mounted disks
df -hiP
- show how blockdevices are configured in system
lsblk
2.2 Memory
- Show memory statistics
free -th
- Top provides memory information as well
top
3 Services
- list all services
systemctl list-units --type service
- List failed services on boot
systemctl --failed
- show all running services
systemctl --all --state=running
- show detailed service status
systemctl start <svc-name>
- service handing
systemctl [start|stop|restart|enable|disable|mask] <svc-name>
- check if service is enabled to autostart after reboot
systemctl is-enabled <svc-name>
4 Events
4.1 Show last boots
journalctl --list-boots last reboot
4.2 Journal
- Show log since last boot
journalctl -b
- Kernel messages (like dmesg)
journalctl -k
- Show latest log and wait for changes
journalctl -f
- Reverse output (newest first)
journalctl -r
- Show only errors and worse
journalctl -b -p err
- Filter on time (example)
journalctl --since=2014-06-00 --until="2014-06-07 12:00:00"
- Since yesterday
journalctl --since=yesterday
- Show only log of SERVICE
journalctl -u SERVICE
- Match executable, e.g. dhclient
journalctl /usr/sbin/dhclient
- Match device node, e.g. /dev/sda
journalctl /dev/sda
4.3 Log Files
- tail all currently open text files
lsof -F | sed '/^n\//!d;s/^n//;s/ .*//' | sort -u | xargs file | grep ' text$' | cut -d: -f1 | xargs tail -fn0
- tail all files under /var/log
tail -f -n0 /var/log/* /var/log/*/*
5 CentOS 8 Stream migration
CentOS8 will be discontinued by the Red Hat team. All the effort will go into CentOS Stream operating System which is a rolling release of CentOS.
You can directly migrate a CentOS8 into a CentOS8 Stream in place:
dnf install centos-release-stream dnf distro-sync cat /etc/centos-release reboot