Linux: Difference between revisions
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Linux is a free Unix-type operating system originally created by [http://en.wikipedia.org/wiki/Linus_Torvalds Linus Torvalds] with the assistance of developers around the world. Developed under the [http://www.linux.org/info/gnu.html GNU General Public License] , the source code for Linux is freely available to everyone. | Linux is a free Unix-type operating system originally created by [http://en.wikipedia.org/wiki/Linus_Torvalds Linus Torvalds] with the assistance of developers around the world. Developed under the [http://www.linux.org/info/gnu.html GNU General Public License] , the source code for Linux is freely available to everyone. | ||
== Links == | == Links == | ||
*[[Linux_kernel|linux kernel]] | |||
*[[Distributions|Distributions]] | |||
*https://kb.novaordis.com/index.php/Events_OS_Metrics | |||
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== Rescue CDs == | == Rescue CDs == | ||
*[ | *[https://www.scientificlinux.org/downloads/ Scientific Linux] | ||
*[[SystemRescueCd|SystemRescueCd]] | |||
*[http://www.knoppix.net/ Knoppix] | |||
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== Checking resources == | |||
*inxi | *inxi | ||
*http://www.slashroot.in/linux-system-io-monitoring | *[http://www.slashroot.in/linux-system-io-monitoring http://www.slashroot.in/linux-system-io-monitoring] | ||
===show what is doing most disk accesses=== | |||
=== show what is doing most disk accesses === | |||
iotop | iotop | ||
glances | glances | ||
===IO statistics=== | === IO statistics === | ||
iostat | iostat | ||
vmstat | vmstat | ||
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atop | atop | ||
===CPU usage etc=== | === CPU usage etc === | ||
top | top | ||
atop | atop | ||
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pidstat | pidstat | ||
==Administration== | == Administration == | ||
*[[Linux Power Management]] | *[https://chrisdown.name/2018/01/02/in-defence-of-swap.html About swap] | ||
*[http://www.suse.de/~agruen/acl/linux-acls/online/ POSIX ACLS] | |||
*[[LVM|LVM]] | |||
*[[Linux_Software_Raid|Linux Software Raid]] | |||
*[http://www-128.ibm.com/developerworks/library/l-bootload.html Boot loader showdown: Getting to know LILO and GRUB] | |||
*[[Linux_Power_Management|Linux Power Management]] | |||
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=== watch which files a process opens === | |||
watch ls -l /proc/`pidof clamd`/fd | |||
=== pam_succeed_if(sudo:auth): requirement "uid >= 1000" not met === | === pam_succeed_if(sudo:auth): requirement "uid >= 1000" not met === | ||
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echo "- - -" > /sys/class/scsi_host/host2/scan | echo "- - -" > /sys/class/scsi_host/host2/scan | ||
The winner so far: | |||
blockdev --rereadpt /dev/sdg | blockdev --rereadpt /dev/sdg | ||
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kpartx -d /dev/mapper/foo | kpartx -d /dev/mapper/foo | ||
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=== Create swapfile === | |||
fallocate -l 4G /var/swapfile | fallocate -l 4G /var/swapfile | ||
mkswap /var/swapfile | mkswap /var/swapfile | ||
Temporary: | |||
swapon -v /var/swapfile | swapon -v /var/swapfile | ||
In fstab: | |||
/var/swapfile swap swap sw,prio=-1 | |||
swapon failed: Invalid argument | swapon failed: Invalid argument | ||
problably trying to use fallocate on rhel/centos, use dd instead | |||
=== partx: error adding partition === | |||
try kpartx instead | |||
[[Category:System Administration]] [[Category:Linux]] | [[Category:System Administration]] [[Category:Linux]] | ||
Revision as of 09:55, 9 June 2021
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
Rescue CDs
Checking resources
*inxi *http://www.slashroot.in/linux-system-io-monitoring
show what is doing most disk accesses
iotop glances
IO statistics
iostat vmstat dstat ioping atop
CPU usage etc
top atop htop vtop fio pidstat
Administration
FAQ
check if virtual of physicalmachine
dmidecode -s system-manufacturer virt-who
watch which files a process opens
watch ls -l /proc/`pidof clamd`/fd
pam_succeed_if(sudo:auth): requirement "uid >= 1000" not met
Grow (GPT) last partition to max available
Where '3' is partition number
parted /dev/sdf resize 3 100%
No longer allowed?
gdisk
timestamp to human readable
date -d @1522142497
List hardware
- lshw
- dmidecode
- lsusb
- hwinfo
- lspci
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 echo 1 > /sys/block/sde/device/rescan
Only one that seemed to work on (centos7.x)
echo "- - -" > /sys/class/scsi_host/host2/scan
The winner so far:
blockdev --rereadpt /dev/sdg
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
