Difference between revisions of "Linux"

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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]]
 


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


*[[SystemRescueCd]]
*[https://www.scientificlinux.org/downloads/ Scientific Linux]  
*[http://www.knoppix.net/ Knoppix]


*[[SystemRescueCd|SystemRescueCd]]
*[http://www.knoppix.net/ Knoppix]
 
== Checking resources ==


==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
Line 27: Line 36:
  atop
  atop


===CPU usage etc===
=== CPU usage etc ===
 
  top
  top
  atop
  atop
Line 35: Line 45:
  pidstat
  pidstat


==Administration==
== 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]
*[https://chrisdown.name/2018/01/02/in-defence-of-swap.html About swap]  
*[[LVM]]
*[http://www.suse.de/~agruen/acl/linux-acls/online/ POSIX ACLS]  
*[[Linux Software Raid]]
*[[LVM|LVM]]  
*[http://www-128.ibm.com/developerworks/library/l-bootload.html Boot loader showdown: Getting to know LILO and GRUB]
*[[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|Linux Power Management]]  


 


== FAQ ==
== FAQ ==
Line 145: Line 157:
  kpartx -d /dev/mapper/foo
  kpartx -d /dev/mapper/foo


 
=== Create swapfile ===


===Create swapfile===
  fallocate -l 4G /var/swapfile
  fallocate -l 4G /var/swapfile
  mkswap /var/swapfile
  mkswap /var/swapfile
Line 152: Line 166:


swapon failed: Invalid argument
swapon failed: Invalid argument
  problably trying to so use it on rhel/centos, use dd instead of fallocate
  problably trying to so use it on rhel/centos, use dd instead of fallocate


 
=== partx: error adding partition ===
try kpartx instead
 


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

Revision as of 13:59, 19 February 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

 

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
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
swapon -v /var/swapfile

swapon failed: Invalid argument

problably trying to so use it on rhel/centos, use dd instead of fallocate


partx: error adding partition

try kpartx instead