Linux
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
Network
check if interface exists
/sys/class/net/$IF
Misc
check if virtual or physical machine
dmidecode -s system-manufacturer virt-who lscpu virt-what
Find bios version
dmidecode -s bios-version
watch which files a process opens
watch ls -l /proc/`pidof clamd`/fd
pam_succeed_if(sudo:auth): requirement "uid >= 1000" not met
timestamp to human readable
date -d @1522142497
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
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}'
pvcreate: Cannot use /dev/sdb: device is partitioned
Even /proc/partitions will confirm there's no partitions, so to convince pvcreate:
wipefs --all /dev/sdb
