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]]
*[[Distributions]]


*[[Linux_kernel|linux kernel]]
*[[Distributions|Distributions]]
*https://kb.novaordis.com/index.php/Events_OS_Metrics
 


== Rescue CDs ==
== Rescue CDs ==
*[https://www.scientificlinux.org/download/ Scientific Linux]


*[[SystemRescueCd]]
*[https://www.scientificlinux.org/downloads/ Scientific Linux]
*[http://www.knoppix.net/ Knoppix]
 
*[[SystemRescueCd|SystemRescueCd]]  
*[http://www.knoppix.net/ Knoppix]  
 
 
 
== Checking resources ==
 
*inxi
*[http://www.slashroot.in/linux-system-io-monitoring 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 ==
 
*[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]]
 
 
 
 
 
 
== FAQ ==
 
=== check if interface exists ===
 
/sys/class/net/$IF
 
=== check if virtual of physicalmachine ===
 
dmidecode -s system-manufacturer
virt-who
 
 
 
===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 ===
 
=== 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 (this one worked on centos 7.3!)
 
This one gave new disk size!
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:


==Administration==
blockdev --rereadpt /dev/sdg
*[http://www.suse.de/~agruen/acl/linux-acls/online/ POSIX ACLS]
*[[LVM]]
*[[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]]
maybe


hdparm -z /dev/sdg


==FAQ==
=== Force reboot ===
===List hardware===
*lshw
*dmidecode


===Force reboot===
I found sometimes 'reboot' and 'shutdown' don't work in virtual machines, in that case try:
I found sometimes 'reboot' and 'shutdown' don't work in virtual machines, in that case try:
  #sync
  #sync
  echo s > /proc/sysrq-trigger
  echo s > /proc/sysrq-trigger
Line 35: Line 156:
  echo b > /proc/sysrq-trigger
  echo b > /proc/sysrq-trigger


[[Category: System Administration]]
=== 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
  [[Category:System Administration]] [[Category:Linux]]

Revision as of 10:51, 8 December 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 interface exists

/sys/class/net/$IF

check if virtual of physicalmachine

dmidecode -s system-manufacturer
virt-who

 

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

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 (this one worked on centos 7.3!)

This one gave new disk size!

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