Linux: Difference between revisions
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== Administration == | == Administration == | ||
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== | = FAQ = | ||
==Storage== | |||
===Umount: /mnt/sda1 is busy=== | |||
Try | |||
umount -lf /mnt/sda1 | |||
=== Grow (GPT) last partition to max available === | |||
Where '3' is partition number | |||
parted /dev/sdf resize 3 100% | |||
No longer allowed? | |||
gdisk | |||
===I deleted a file but disk is still full=== | |||
It was in use by process, you'll need to kill that | |||
lsof -nP | grep '(deleted)' | |||
etc | |||
===Which disk is 0.0.3.0=== | |||
lsblk -dno name,hctl | |||
===Power-on or device reset occurred=== | |||
I had a case where megamaid decided to spin down "unused disks" that were in JBOD. Disable that option ot switch the controller to '''IT mode'''. | |||
==Network== | |||
=== check if interface exists === | === check if interface exists === | ||
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/sys/class/net/$IF | /sys/class/net/$IF | ||
==Hardware info== | |||
===Check number of CPUs=== | |||
lscpu | lscpu | grep Socket | ||
===Find bios version=== | ===Find bios version=== | ||
dmidecode -s bios-version | dmidecode -s bios-version | ||
=== pam_succeed_if(sudo:auth): requirement "uid >= 1000" not met === | === pam_succeed_if(sudo:auth): requirement "uid >= 1000" not met === | ||
=== List hardware === | === List hardware === | ||
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This one gave new disk size! | This one gave new disk size! | ||
Verified: CentOS 6, Ubuntu 22 | |||
echo 1 > /sys/block/sde/device/rescan | echo 1 > /sys/block/sde/device/rescan | ||
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#reboot | #reboot | ||
echo b > /proc/sysrq-trigger | echo b > /proc/sysrq-trigger | ||
==Misc== | |||
===check if you're in virtual or physical machine=== | |||
dmidecode -s system-manufacturer | |||
virt-who | |||
lscpu | |||
virt-what | |||
=== watch which files a process opens === | |||
watch ls -l /proc/`pidof clamd`/fd | |||
=== timestamp to human readable === | |||
date -d @1522142497 | |||
=== Mignight commander/dialog strange characters === | === Mignight commander/dialog strange characters === | ||
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find /var/www -type d | awk -F"/" 'NF > max {max = NF} END {print max}' | find /var/www -type d | awk -F"/" 'NF > max {max = NF} END {print max}' | ||
[[Category:System Administration]] [[Category:Linux]] | [[Category:System Administration]] [[Category:Linux]] | ||
==Booting== | |||
===Cannot open access to console, the root account is locked=== | |||
You probably messed up your grub config, maybe GRUB_CMDLINE_LINUX. Boot rescue CD image :) | |||
Latest revision as of 08:10, 25 July 2024
Linux is a free Unix-type operating system originally created by Linus Torvalds with the assistance of developers around the world. Developed under the GNU General Public License , the source code for Linux is freely available to everyone.
Links
- linux kernel
- Distributions
- https://kb.novaordis.com/index.php/Events_OS_Metrics
- Linux on ircnet: #linux2
Rescue CDs
Administration
FAQ
Storage
Umount: /mnt/sda1 is busy
Try
umount -lf /mnt/sda1
Grow (GPT) last partition to max available
Where '3' is partition number
parted /dev/sdf resize 3 100%
No longer allowed?
gdisk
I deleted a file but disk is still full
It was in use by process, you'll need to kill that
lsof -nP | grep '(deleted)'
etc
Which disk is 0.0.3.0
lsblk -dno name,hctl
Power-on or device reset occurred
I had a case where megamaid decided to spin down "unused disks" that were in JBOD. Disable that option ot switch the controller to IT mode.
Network
check if interface exists
/sys/class/net/$IF
Hardware info
Check number of CPUs
lscpu | grep Socket
Find bios version
dmidecode -s bios-version
pam_succeed_if(sudo:auth): requirement "uid >= 1000" not met
List hardware
- lshw
- dmidecode
- lsusb
- hwinfo
- lspci
- lscpu
dmidecode -t baseboard
BLKRRPART: Device or resource busy
spend all day or reboot
calling ioclt to re-read partition table: Device or resource busy
rescan partition table
Keep an eye on
cat /proc/partitions
Partition(s) have been written, but we have been unable to inform the kernel of the change
partprobe kpartx /dev/sdg partx -uv /dev/sdg (this one worked on centos 7.3!)
This one gave new disk size! Verified: CentOS 6, Ubuntu 22
echo 1 > /sys/block/sde/device/rescan
Only one that seemed to work on (centos7.x)
echo "- - -" > /sys/class/scsi_host/host2/scan
or scan all:
echo "- - -" | tee /sys/class/scsi_host/host*/scan
The winner so far:
blockdev --rereadpt /dev/sdg
but may throw blockdev: ioctl error on BLKRRPART: Device or resource busy
maybe
hdparm -z /dev/sdg
Force reboot
I found sometimes 'reboot' and 'shutdown' don't work in virtual machines, in that case try:
#sync echo s > /proc/sysrq-trigger #optionally umount echo u > /proc/sysrq-trigger #reboot echo b > /proc/sysrq-trigger
Misc
check if you're in virtual or physical machine
dmidecode -s system-manufacturer virt-who lscpu virt-what
watch which files a process opens
watch ls -l /proc/`pidof clamd`/fd
timestamp to human readable
date -d @1522142497
Mignight commander/dialog strange characters
Quick fix:
export LANG=en_US.ISO-8859-1
This probleem seems to be related to screen/su -
kpartx failing silently
No output/result when trying to create:
kpartx -lv /dev/mapper/foo
this might means the device hasn't been partitioned
No output when trying to delete:
kpartx -d /dev/mapper/foop1
means you should use
kpartx -d /dev/mapper/foo
Create swapfile
fallocate -l 4G /var/swapfile mkswap /var/swapfile
Temporary:
swapon -v /var/swapfile
In fstab: /var/swapfile swap swap sw,prio=-1
swapon failed: Invalid argument
problably trying to use fallocate on rhel/centos, use dd instead
partx: error adding partition
try kpartx instead
Find maximum depth of directory
find /var/www -type d | awk -F"/" 'NF > max {max = NF} END {print max}'
Booting
Cannot open access to console, the root account is locked
You probably messed up your grub config, maybe GRUB_CMDLINE_LINUX. Boot rescue CD image :)
