system

references:

drop caches

$ sudo bash -c "echo 3 > /proc/sys/vm/drop_caches"

hardware spec

[!TIP|label:hardware spec] list info

  • glances

  • hwinfo

  • lshw

  • lscpu

  • lsmem

  • lspci

  • lsscsi

  • lsusb

  • inxi ( inxi --recommends, inxi -F|--full )

  • lsblk

  • lsof

  • ncdu - a disk utility for Unix systems

  • fdisk

  • blkid - command-line utility to locate/print block device attributes

  • mount

  • free

  • dmidecode

  • hdparm

  • lstopo-no-graphics

  • hwloc-ls

  • /proc

    • /proc/cpuinfo

    • /proc/meminfo

    • /proc/version

    • /proc/scsi/scsi

    • /proc/partitions

performance & analysis

  • * imarslo : adminTools

  • vmstat - shows system memory, processes, interrupts, paging, block I/O, and CPU info

  • iostat - for storage I/O statistics.

  • iotop - interactive I/O viewer. Get an overview of storage r/w activity

  • netstat – for network statistics

  • iftop - network traffic viewer

  • nload - a super simple, command-line network interface monitoring tool

  • mtr - network diagnostic tool

  • dig - DNS lookup utility tool

  • nethogs - network traffic analyzer

  • apropos - search man page names and descriptions

  • fsck - tool for checking the consistency of a file system

  • vnstat

  • dstat

  • mpstat

  • ss - socket statistics

  • sar

  • nethogs - network traffic analyzer

lshw Classes

  • address

  • bridge

  • bus

  • communication

  • disk

  • display

  • generic

  • input

  • memory

  • multimedia

  • network

  • power

  • printer

  • processor

  • storage

  • system

  • tape

  • volume

os

$ lsb_release -a
LSB Version    : :core-4.1-amd64:core-4.1-noarch
Distributor ID : CentOS
Description    : CentOS Linux release 7.9.2009 (Core)
Release        : 7.9.2009
Codename       : Core

$ uname  -a
Linux my-computer 3.10.0-1160.42.2.el7.x86_64 #1 SMP Tue Sep 7 14:49:57 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

$ cat /etc/centos-release
CentOS Linux release 7.9.2009 (Core)

hardware

$ sudo dmidecode -s

system information

$ sudo dmidecode | grep -A5 '^System Information'
  System Information
    Manufacturer: HPE
    Product Name: ProLiant DL380 Gen10
    Version: Not Specified
    Serial Number: S*************0
    UUID: 0******0-0**0-0**0-0**0-3**********e

# or display system [m]anufacture
$ inxi -M
    Machine:   Type: Server Mobo: HPE model: ProLiant DL380 Gen10 serial: <root required> UEFI: HPE v: U30
               date: 06/15/2018
# or
$ sudo inxi --dmidecode -Mxxx
    Machine:   Type: Rack Mount Chassis Mobo: HPE model: ProLiant DL380 Gen10 serial: PFARA%%LMAZ6XB BIOS: HPE
           v: U30 rev: 1.40 date: 06/15/2018 rom size: 16384 kB

manufacturer

$ sudo dmidecode -s system-manufacturer
    HPE

# or
$ sudo dmidecode -s baseboard-manufacturer
HPE

# or
$ cat /sys/devices/virtual/dmi/id/sys_vendor
HPE

product name and version

product name only

$ sudo dmidecode -s system-product-name
    ProLiant DL380 Gen10

# or
$ sudo dmidecode -s baseboard-product-name
ProLiant DL380 Gen10

# or
$ cat /sys/devices/virtual/dmi/id/product_name
ProLiant DL380 Gen10

# or
$ sudo dmidecode | grep -i prod
        Product Name: Vostro 5560
        Product Name: 04YDT0

uuid

$ sudo dmidecode | grep -i uuid | awk '{print $2}' | tr '[:upper:]' '[:lower:]'

cpu

references:

cpu cores

$ cat /proc/cpuinfo | egrep "core id|physical id" | tr -d "\n" | sed s/physical/\\nphysical/g | grep -v ^$ | sort | uniq | wc -l
36

# or
$ grep -c processor /proc/cpuinfo
32

# or
$ nproc --all
32

# or
$ getconf _NPROCESSORS_ONLN
32

# or
$ cat /sys/devices/system/cpu/present
0-31

# or CPUs = Threads per core X cores per socket X socket
$ lscpu | grep -E '^Thread|^Core|^Socket|^CPU\('
CPU(s):                32
Thread(s) per core:    2
Core(s) per socket:    8
Socket(s):             2
$ lscpu | grep --color=none -E '^(Thread|Core|Socket|CPU\(|NUMA|Model\ name)'
CPU(s):              128
Thread(s) per core:  2
Core(s) per socket:  64
Socket(s):           1
NUMA node(s):        1
Model name:          AMD EPYC 7742 64-Core Processor
NUMA node0 CPU(s):   0-127

# or
$ sudo dmidecode -t 4 | grep -E 'Socket Designation|Count'
  Socket Designation: CPU1
  Core Count: 8
  Thread Count: 16
  Socket Designation: CPU2
  Core Count: 8
  Thread Count: 16

# list clock speed
$ sudo lscpu | grep --color=none -E '^(Thread|Core|Socket|CPU\(|NUMA\ node\(|Model\ name|CPU.+MHz|BogoMIPS)'
CPU(s):              32
Thread(s) per core:  2
Core(s) per socket:  8
Socket(s):           2
NUMA node(s):        2
Model name:          Intel(R) Xeon(R) CPU E5-2667 v4 @ 3.20GHz
CPU MHz:             1719.616
CPU max MHz:         3600.0000
CPU min MHz:         1200.0000
BogoMIPS:            6399.86

  • others

    $ lscpu --all --extended
$ lscpu --all --parse=CPU,SOCKET,CORE | grep -v '^#'

check CPU support 64 bit or not

$ sudo dmidecode --type=processor | grep -i -A 1 Characteristics
    Characteristics:
            64-bit capable

cat /proc/cpuinfo

$ lscpu
Architecture:          i686
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                4
On-line CPU(s) list:   0-3
....

cpu info

$ sudo dmidecode -t processor

# or
$ sudo lshw -C cpu

# or
$ sudo dmidecode -t 4 | egrep -i "Designation|Intel|core|thread"

# or
$ inxi -C
CPU:
  Info: 2x 8-core model: Intel Xeon E5-2667 v4 bits: 64 type: MT MCP SMP cache: L2: 2x 2 MiB (4 MiB)
  Speed (MHz): avg: 1324 min/max: 1200/3600 cores: 1: 1202 2: 1202 3: 1251 4: 1200 5: 1201
    6: 1376 7: 1260 8: 1205 9: 1203 10: 1202 11: 1201 12: 1201 13: 1201 14: 1202 15: 1201 16: 1202
    17: 1200 18: 1200 19: 1600 20: 1199 21: 1201 22: 1287 23: 1892 24: 1201 25: 1200 26: 1201
    27: 3200 28: 1200 29: 1200 30: 1701 31: 1201 32: 1200

memory

references:

list total memory

[!TIP|label:references:]

$ hwinfo --memory | grep 'Memory Size'
  Memory Size: 128 GB

$ sudo lshw -short | grep 'System Memory'
/0/2c                           memory         128GiB System Memor

$ vmstat -s -S M | egrep -ie 'total memory'
       128817 M total memory

$ vmstat -s | grep "total memory"
    131909608 K total memory

$ vmstat -s | awk '{print $1 / 1024 / 1024}' | head -1
125.799

$ inxi -F | grep "Memory"
  Processes: 414 Uptime: 87d 17h 40m Memory: 125.8 GiB used: 27.21 GiB (21.6%) Init: systemd

$ sudo dmidecode -t memory | grep  Size: | grep -v "No Module Installed" | awk '{sum+=$2}END{print sum}'
131072

$ egrep 'MemTotal|MemFree|MemAvailable' /proc/meminfo
MemTotal:       131909608 kB
MemFree:        95760488 kB
MemAvailable:   104355708 kB

$ vmstat -s

list only installed RAM modules

$ sudo dmidecode -t memory | grep  Size: | grep -v "No Module Installed"
$ sudo dmidecode -t memory | grep -E '(^Memory Device|^\s+(Size:|Type:|Type Detail:|Serial Number:|Part Number:|Memory Technology:|Manufacturer))' --color=never | grep -v -E 'Not Specified|No Module Installed|Unknow|None|OUT OF SPEC'

memory information

$ sudo dmidecode -t memory
$ sudo dmidecode -t memory | grep -E '(^Memory Device|^\s+(Size:|Type:|Type Detail:|Serial Number:|Part Number:|Memory Technology:|Configured Memory Speed:|Manufacturer))' --color=never
Memory Device
  Size: 16384 MB
  Type: DDR4
  Type Detail: Synchronous Registered (Buffered)
  Manufacturer: 00AD063200AD
  Serial Number: 44965EB1
  Part Number: HMA82GR7DJR8N-XN
  Configured Memory Speed: 2933 MT/s
  Memory Technology: DRAM
# or
$ sudo dmidecode -t memory | grep -E '(^Memory Device|^\s+(Size:|Type:|Type Detail:|Serial Number:|Part Number:|Memory Technology:|Configured Memory Speed:|Manufacturer))' --color=never | grep -v -E 'Not Specified|No Module|Unknow|None|<OUT OF SPEC>'

# or
$ sudo lshw -C memory
$ sudo lshw -short -class memory

# Physical Memory Array
$ sudo dmidecode --type 16

# get Memory Device
$ sudo dmidecode --type 17

# Memory Array Mapped Address
$ sudo dmidecode --type 19

print memory only

$ ps -o comm,%mem,args -u marslo | more
COMMAND         %MEM COMMAND
gnome-keyring-d  0.0 /usr/bin/gnome-keyring-daemon --daemonize --login
init             0.0 init --user
ssh-agent        0.0 ssh-agent
dbus-daemon      0.0 dbus-daemon --fork --session --address=unix:abstract=/tmp/dbus-i5FUVjzADG
upstart-event-b  0.0 upstart-event-bridge
window-stack-br  0.0 /usr/lib/i386-linux-gnu/hud/window-stack-bridge
upstart-dbus-br  0.0 upstart-dbus-bridge --daemon --session --user --bus-name session
upstart-dbus-br  0.0 upstart-dbus-bridge --daemon --system --user --bus-name system
upstart-file-br  0.0 upstart-file-bridge --daemon --user
ibus-daemon      0.1 /usr/bin/ibus-daemon --daemonize --xim
....

check memory in time

$ free -h -s 5

# or
$ vmstat -w

# or
$ dmesg | grep "Memory"
[    0.995127] Memory: 131882904K/134101416K available (12300K kernel code, 2504K rwdata, 3684K rodata, 2340K init, 3240K bss, 2218512K reserved, 0K cma-reserved)
[    1.139890] x86/mm: Memory block size: 2048MB

bios

$ sudo dmidecode -t bios

disk

  • hwinfo

    $ hwinfo --disk --only /dev/sda
192: SCSI 20.0: 10600 Disk
  [Created at block.245]
  Unique ID: R7kM.qzo5k6MLsu5
  Parent ID: svHJ.VbV94345RfA
  SysFS ID: /class/block/sda
  SysFS BusID: 0:2:0:0
  SysFS Device Link: /devices/pci0000:00/0000:00:02.0/0000:03:00.0/host0/target0:2:0/0:2:0:0
  Hardware Class: disk
  Model: "AVAGO SMC3108"
  Vendor: "AVAGO"
  Device: "SMC3108"
  Revision: "4.68"
  Driver: "megaraid_sas", "sd"
  Driver Modules: "megaraid_sas"
  Device File: /dev/sda (/dev/sg1)
  Device Files: /dev/sda, /dev/disk/by-id/scsi-360030480243a18012424538006708dc9, /dev/disk/by-id/wwn-0x60030480243a18012424538006708dc9, /dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:0:0
  Device Number: block 8:0-8:15 (char 21:1)
  BIOS id: 0x80
  Drive status: no medium
  Config Status: cfg=new, avail=yes, need=no, active=unknown
  Attached to: #37 (RAID bus controller)

disk type

[!INFO] Check disk interface types

  • Advanced technology attachment (ATA)

  • Integrated Drive Electronics (IDE)

  • Serial ATA (SATA)

  • Small Computer system interface (SCSI)

  • Serial attached SCSI (SAS)

  • Fibre Channel

  • lsblk

    $ lsblk -do name,tran
NAME TRAN
sdb  sas
sdc  sas

  • lshw

    $ sudo lshw -c storage -c disk
  ...
  *-sas
       description: Serial Attached SCSI controller
       product: Smart Storage PQI 12G SAS/PCIe 3
       vendor: Adaptec
       physical id: 0
       bus info: pci@0000:5c:00.0
       logical name: scsi1
       version: 01
       width: 64 bits
       clock: 33MHz
       capabilities: sas pm msix pciexpress bus_master cap_list
       configuration: driver=smartpqi latency=0
       resources: irq:32 memory:e9100000-e9107fff ioport:8000(size=256)
     *-disk:0
          description: SCSI Disk                            # SCSC
          product: LOGICAL VOLUME
          vendor: HPE
          physical id: 1.0.0
          bus info: scsi@1:1.0.0
          logical name: /dev/sdb
          version: 1.99
          serial: P************C
          size: 1788GiB (1920GB)
          capabilities: 15000rpm gpt-1.00 partitioned partitioned:gpt
          configuration: ansiversion=5 guid=eda10475-9cdb-44cd-8dbd-28bf482b0e25 logicalsectorsize=512 sectorsize=4096

  • hdparm

    $ sudo hdparm -I /dev/sdb

/dev/sdb:
SG_IO: bad/missing sense data, sb[]:  7***

ATA device, with non-removable media
Standards:
  Likely used: 1
Configuration:
  Logical   max current
  cylinders 0 0
  heads   0 0
  sectors/track 0 0
  --
  Logical/Physical Sector size:           512 bytes
  device size with M = 1024*1024:           0 MBytes
  device size with M = 1000*1000:           0 MBytes
  cache/buffer size  = unknown
Capabilities:
  IORDY not likely
  Cannot perform double-word IO
  R/W multiple sector transfer: not supported
  DMA: not supported
  PIO: pio0

  • SSD or HHD

    [!INFO]

    • check rotational

      # HHD
$ cat /sys/block/sd*/queue/rotational
1
1

# SSD
$ lsscsi
[0:0:0:0]    disk    Generic- SD/MMC CRW       1.00  /dev/sda
[1:0:0:0]    enclosu HPE      Smart Adapter    1.99  -
[1:1:0:0]    disk    HPE      LOGICAL VOLUME   1.99  /dev/sdb
[1:1:0:1]    disk    HPE      LOGICAL VOLUME   1.99  /dev/sdc
[1:2:0:0]    storage HPE      P408i-a SR Gen10 1.99  -
[devops@dc5-ssdfw11 ~]$ cat /sys/block/sd*/queue/rotational
1
0
0

    • lsblk

      ## SSD
$ lsblk -d -o name,rota
NAME ROTA
sdb     0
sdc     0

# or
## SSD
$ lsblk -d -e 7 -o NAME,ROTA,DISC-MAX,MODEL
NAME ROTA DISC-MAX MODEL
sdb     0       0B LOGICAL VOLUME
sdc     0       0B LOGICAL VOLUME
## HHD
$ lsblk -d -e 7 -o NAME,ROTA,DISC-MAX,MODEL
NAME ROTA DISC-MAX MODEL
sdb     1       0B SMC3108
sda     1       0B SMC3108

    • smartctl ( $ yum install smartmontools )

      $ sudo smartctl -a /dev/sdb1
smartctl 7.0 2018-12-30 r4883 [x86_64-linux-4.19.12-1.el7.elrepo.x86_64] (local build)
Copyright (C) 2002-18, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Vendor:               AVAGO
Product:              SMC3108
Revision:             4.68
Compliance:           SPC-3
User Capacity:        7,679,267,307,520 bytes [7.67 TB]
Logical block size:   512 bytes
Physical block size:  4096 bytes
Logical Unit id:      0x60030480243a7b0124d58c0646f9617d
Serial number:        007d61f946068cd524017b3a24800403
Device type:          disk
Local Time is:        Thu Mar 30 10:51:52 2023 PDT
SMART support is:     Unavailable - device lacks SMART capability.

=== START OF READ SMART DATA SECTION ===
Current Drive Temperature:     0 C
Drive Trip Temperature:        0 C

## SSD
$ sudo smartctl -a /dev/sdc
smartctl 6.6 2017-11-05 r4594 [x86_64-linux-4.18.0-193.28.1.el8_2.x86_64] (local build)
Copyright (C) 2002-17, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Vendor:               HPE
Product:              LOGICAL VOLUME
Revision:             1.99
User Capacity:        1,920,349,855,744 bytes [1.92 TB]
Logical block size:   512 bytes
Rotation Rate:        Solid State Device                          # SSD
Logical Unit id:      0x600508b1001c5be1882c0a4afb83c8ec
Serial number:        P************C
Device type:          disk
Local Time is:        Thu Mar 30 10:53:12 2023 PDT
SMART support is:     Available - device has SMART capability.
SMART support is:     Enabled
Temperature Warning:  Disabled or Not Supported

=== START OF READ SMART DATA SECTION ===
SMART Health Status: OK
Current Drive Temperature:     0 C
Drive Trip Temperature:        0 C

    • /proc/scsi/scsi

      ## SSD
$ cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
  Vendor: Generic- Model: SD/MMC CRW       Rev: 1.00
  Type:   Direct-Access                    ANSI  SCSI revision: 06
Host: scsi1 Channel: 00 Id: 00 Lun: 00
  Vendor: HPE      Model: Smart Adapter    Rev: 1.99
  Type:   Enclosure                        ANSI  SCSI revision: 05
Host: scsi1 Channel: 01 Id: 00 Lun: 00
  Vendor: HPE      Model: LOGICAL VOLUME   Rev: 1.99
  Type:   Direct-Access                    ANSI  SCSI revision: 05
Host: scsi1 Channel: 01 Id: 00 Lun: 01
  Vendor: HPE      Model: LOGICAL VOLUME   Rev: 1.99
  Type:   Direct-Access                    ANSI  SCSI revision: 05
Host: scsi1 Channel: 02 Id: 00 Lun: 00
  Vendor: HPE      Model: P408i-a SR Gen10 Rev: 1.99
  Type:   RAID                             ANSI  SCSI revision: 05

check status

  • $ lsblk

  • $ pvs

  • $ lvs

  • $ vgs

  • $ pvscan

  • $ lvscan

  • $ pvdisplay

  • $ vgdisplay

  • $ lvdisplay

  • $ fdisk -l

  • $ sfdisk -l -uM

  • $ lshw -class disk

  • $ hwinfo --block --short

  • $ cat /proc/partitions

  • $ sudo hdparm -I /dev/sda

RAID Info

[!NOTE|label:references:]

$ sudo apt install -y smartmontools

# RAID1
$ sudo smartctl --scan
/dev/sda -d scsi # /dev/sda, SCSI device
/dev/bus/0 -d megaraid,0 # /dev/bus/0 [megaraid_disk_00], SCSI device
/dev/bus/0 -d megaraid,1 # /dev/bus/0 [megaraid_disk_01], SCSI device

RAID details info

$ sudo smartctl --all -d megaraid,1 /dev/sda
smartctl 7.1 2019-12-30 r5022 [x86_64-linux-5.15.0-107-generic] (local build)
Copyright (C) 2002-19, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Device Model:     HF***********9N
Serial Number:    EJ*************4P
LU WWN Device Id: 5 ace42e 02565881c
Add. Product Id:  DELL(tm)
Firmware Version: DZ02
User Capacity:    960,197,124,096 bytes [960 GB]
Sector Sizes:     512 bytes logical, 4096 bytes physical
Rotation Rate:    Solid State Device
Form Factor:      2.5 inches
Device is:        Not in smartctl database [for details use: -P showall]
ATA Version is:   ACS-4 (minor revision not indicated)
SATA Version is:  SATA 3.3, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is:    Wed Jun  5 16:34:16 2024 PDT
SMART support is: Available - device has SMART capability.
SMART support is: Enabled

# or even more details
$ sudo smartctl --xall -d megaraid,1 /dev/sda

network

get network cards

$ sudo lshw -short -class network
H/W path            Device        Class          Description
============================================================
/0/100/1/0          enp1s0f0      network        I350 Gigabit Network Connection
/0/100/1/0.1        enp1s0f1      network        I350 Gigabit Network Connection
/0/100/1.1/0        enp2s0f0      network        Ethernet Controller X710 for 10GbE SFP+
/0/100/1.1/0.1      enp2s0f1      network        Ethernet Controller X710 for 10GbE SFP+
/0/2/0              enp131s0f0    network        Ethernet Controller 10-Gigabit X540-AT2
/0/2/0.1            enp131s0f1    network        Ethernet Controller 10-Gigabit X540-AT2
/3                  veth8c9c4570  network        Ethernet interface
/4                  flannel.1     network        Ethernet interface
/5                  veth8d141a78  network        Ethernet interface
/6                  veth3cc4bf19  network        Ethernet interface
/7                  cni0          network        Ethernet interface
/8                  docker0       network        Ethernet interface
/9                  veth179b5dab  network        Ethernet interface

network speed

$ ifstat -n -i en7
       en7
 KB/s in  KB/s out
    7.35      1.15
    4.91      1.02
    6.05      0.80
    8.36      1.78

get the public ip address

$ curl ifconfig.me

environment variables

show PATH

$ echo src::${PATH} | awk 'BEGIN{pwd=ENVIRON["PWD"];RS=":";FS="\n"}!$1{$1=pwd}$1!~/^\//{$1=pwd"/"$1}{print $1}'
/home/marslo/src
/home/marslo
/home/marslo/.vim/tools/bin
/usr/local/mysql/bin
/usr/local/bcompare/bin
/usr/lib/lightdm/lightdm
/usr/local/sbin
/usr/local/bin
/usr/sbin
/usr/bin
/sbin
/bin
/usr/games
/usr/local/games
OR
$ echo "${PATH//:/$'\n'}"

graphics card driver

[!NOTE|label:references:]

get system info

references:

top

ps

[!TIP|label:references:]

  • ultimate ps command

    $ G=$(stty -g); stty rows $((${LINES:-50}/2)); top -n1; stty $G; unset G

  • get cpu

    $ ps -eocomm,pcpu | egrep -v '(0.0)|(%CPU)'
systemd          0.2
rcu_sched        0.2
sshd             0.5
java             8.2
java             0.6
dockerd         16.1
docker-containe  0.6
...

  • get memory

    $ ps -eocomm,pmem | egrep -v '(0.0)|(%MEM)'
java             0.1
java             0.1
java             0.8
gvfs-udisks2-vo  0.1
kube-apiserver   0.1

  • sort process by PID

    $ ps -axww

  • check the group PID

    $ ps -xj

  • top 10 process

    $ ps aux | sort -nk +4 | tail

  • discover the process start time

    $ ps -eo pid,lstart,cmd

  • get date of latest prcess startup time

    $ ps -o lstart <pid>

  • real-time process monitoring

    $ watch -n 1 'ps -eo pid,ppid,cmd,%mem,%cpu --sort=-%mem | head'

  • using tee for process

    $ echo "tee can split a pipe in two"|tee >(rev) >(tr ' ' '_')

find the zombie process

$ ps aux | awk '{ print $8 " " $2 " " $11}' | grep -w Z

set system info

clear duplicated PATH

$ export PATH=`echo -n $PATH | awk -v RS=":" '{ if (!x[$0]++) {printf s $0; s=":"} }'`

sysctl

change max_user_watches

# permanent
$ sudo bash -c "echo fs.inotify.max_user_watches=524288 >> /etc/sysctl.conf"
$ sudo sysctl -p

# temporary
$ sudo sysctl fs.inotify.max_user_watches=524288

  • verify

    $ cat /proc/sys/fs/inotify/max_user_watches

change net.bridge

$ sudo modprobe br_netfilter
$ sudo sysctl net.bridge.bridge-nf-call-iptables=1
$ sudo sysctl net.bridge.bridge-nf-call-ip6tables=1

# or
$ sudo bash -c "cat >  /etc/sysctl.d/k8s.conf" << EOF
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF

  • check status

    $ sudo sysctl --system

LS_COLORS

[!NOTE|label:references:]

  • show database

    $ dircolors --print-database
$ which -a dircolors
/usr/local/opt/coreutils/libexec/gnubin/dircolors

$ echo $COLORTERM
truecolor
$ echo $TERM
xterm-256color

  • setup LS_COLORS

    # with background color
$ export LS_COLORS='*.patch=48;5;197;38;5;232;1:'

# with italic
$ export LS_COLORS='*.bak=38;5;241;3'

# with underline
$ export LS_COLORS='*.xlsxm=38;5;112;4:'

# with italic and underline
$ export LS_COLORS='*.patch=38;5;197;3;4:'

# with italic and underline and blink
$ export LS_COLORS='*.patch=38;5;197;3;4;5:"'
#                            ^       ^ ^ ^
#                            +       + + + blink
#                            +       + + underline
#                            +       + italic
#                            + frontend color

    !LS_COLORS example

  • show current settings

    ( # Run in a subshell so it won't crash current color settings
  dircolors -b >/dev/null
  IFS=:
  for ls_color in ${LS_COLORS[@]}; do # For all colors
      color=${ls_color##*=}
      ext=${ls_color%%=*}
      echo -en "\E[${color}m${ext}\E[0m " # echo color and extension
  done
  echo
)

    • or Script to show colors

      declare -A descriptions=(
    [bd]="block device"
    [ca]="file with capability"
    [cd]="character device"
    [di]="directory"
    [do]="door"
    [ex]="executable file"
    [fi]="regular file"
    [ln]="symbolic link"
    [mh]="multi-hardlink"
    [mi]="missing file"
    [no]="normal non-filename text"
    [or]="orphan symlink"
    [ow]="other-writable directory"
    [pi]="named pipe, AKA FIFO"
    [rs]="reset to no color"
    [sg]="set-group-ID"
    [so]="socket"
    [st]="sticky directory"
    [su]="set-user-ID"
    [tw]="sticky and other-writable directory"
)

IFS=:
for ls_color in $LS_COLORS; do
    color="${ls_color#*=}"
    type="${ls_color%=*}"

    # Add description for named types.
    desc="${descriptions[$type]}"

    # Separate each color with a newline.
    if [[ $color_prev ]] && [[ $color != "$color_prev" ]]; then
        echo
    fi

    printf "\e[%sm%s%s\e[m " "$color" "$type" "${desc:+ ($desc)}"

    # For next loop
    color_prev="$color"
done
echo

  • settings

    $ cat ~/.bashrc
LS_COLORS='bd=38;5;68:ca=38;5;17:cd=38;5;113;1:di=38;5;108:do=38;5;127:ex=38;5;31;1:pi=38;5;126:fi=0:ln=target:mh=38;5;222;1:no=0:or=48;5;196;38;5;232;1:ow=38;5;220;1:sg=48;5;3;38;5;0:su=38;5;220;1;3;100;1:so=38;5;197:st=38;5;86;48;5;234:tw=48;5;235;38;5;139;3:'
LS_COLORS+='*.7z=38;5;64:*.WARC=38;5;64:*.a=38;5;64:*.arj=38;5;64:*.br=38;5;64:*.bz2=38;5;64:*.cpio=38;5;64:*.gz=38;5;64:*.lrz=38;5;64:*.lz=38;5;64:*.lzma=38;5;64:*.lzo=38;5;64:*.rar=38;5;64:*.s7z=38;5;64:*.sz=38;5;64:*.tar=38;5;64:*.tbz=38;5;64:*.tgz=38;5;64:*.warc=38;5;64:*.xz=38;5;64:*.z=38;5;64:*.zip=38;5;64:*.zipx=38;5;64:*.zoo=38;5;64:*.zpaq=38;5;64:*.zst=38;5;64:*.zstd=38;5;64:*.zz=38;5;64:*@.service=38;5;45:'
LS_COLORS+='*.pub=1;3:*.1p=38;5;7:*.32x=38;5;213:*.3g2=38;5;115:*.3ga=38;5;137;1:*.3gp=38;5;115:*.3p=38;5;7:*.82p=38;5;121:*.83p=38;5;121:*.8eu=38;5;121:*.8xe=38;5;121:*.8xp=38;5;121:*.A64=38;5;213:*.BUP=38;5;241:*.CFUserTextEncoding=38;5;239:*.F=38;5;81:*.F03=38;5;81:*.F08=38;5;81:*.F90=38;5;81:*.F95=38;5;81:*.IFO=38;5;114:*.M=38;5;110:*.PDF=38;5;141:*.PFA=38;5;66:*.PL=38;5;160:*.RData=38;5;178:*.Rproj=38;5;11:*.S=38;5;110:*.S3M=38;5;137;1:*.SKIP=38;5;244:*.TIFF=38;5;97:*.VOB=38;5;115;1:*.a00=38;5;213:*.a52=38;5;213:*.a64=38;5;213:*.a78=38;5;213:*.aac=38;5;137;1:*.accdb=38;5;60:*.accde=38;5;60:*.accdr=38;5;60:*.accdt=38;5;60:*.adf=38;5;213:*.adoc=38;5;184:*.afm=38;5;66:*.agda=38;5;81:*.agdai=38;5;110:*.ai=38;5;99:*.aiff=38;5;136;1:*.alac=38;5;136;1:*.allow=38;5;112:*.am=38;5;242;3:*.amr=38;5;137;1:*.application=38;5;116:*.aria2=38;5;241:*.asciidoc=38;5;184:*.asf=38;5;115:*.asm=38;5;81:*.ass=38;5;117:*.astro=38;5;135;1:*.atr=38;5;213:*.au=38;5;137;1:*.automount=38;5;45:*.bib=38;5;178:*.bsp=38;5;215:*.cab=38;5;215:*.caf=38;5;137;1:*.cap=38;5;29:*.car=38;5;57:*.cbr=38;5;141:*.cbz=38;5;141:*.cda=38;5;136;1:*.cdi=38;5;213:*.cdr=38;5;97:*.chm=38;5;141:*.cjs=38;5;074;1:*.cl=38;5;81:*.clj=38;5;41:*.cljc=38;5;41:*.cljs=38;5;41:*.cljw=38;5;41:*.cnc=38;5;7:*.coffee=38;5;079;1:*.comp=38;5;136:*.cp=38;5;75:*.cr=38;5;81:*.crx=38;5;215:*.cs=38;5;81:*.csv=38;5;78:*.ctp=38;5;81:*.cue=38;5;116:*.dart=38;5;51:*.dat=38;5;137;1:*.db=38;5;60:*.def=38;5;7:*.deny=38;5;196:*.description=38;5;116:*.device=38;5;45:*.dhall=38;5;178:*.dicom=38;5;97:*.diff=38;5;197;3;4:*.directory=38;5;116:*.divx=38;5;114:*.djvu=38;5;141:*.dmp=38;5;29:*.doc=38;5;111:*.docm=38;5;111;4:*.docx=38;5;111:*.drw=38;5;99:*.dtd=38;5;178:*.dts=38;5;137;1:*.dwg=38;5;216:*.dylib=38;5;241:*.ear=38;5;215:*.ejs=38;5;135;1:*.el=38;5;81:*.elc=38;5;241:*.eln=38;5;241:*.eml=38;5;90;1:*.entitlements=1:*.epf=1:*.eps=38;5;99:*.epsf=38;5;99:*.epub=38;5;141:*.err=38;5;160;1:*.error=38;5;160;1:*.etx=38;5;184:*.ex=38;5;7:*.example=38;5;7:*.f=38;5;81:*.f03=38;5;81:*.f08=38;5;81:*.f4v=38;5;115:*.f90=38;5;81:*.f95=38;5;81:*.fcm=38;5;137;1:*.feature=38;5;7:*.flac=38;5;136;1:*.flif=38;5;97:*.flv=38;5;115:*.fm2=38;5;213:*.fmp12=38;5;60:*.fnt=38;5;66:*.fon=38;5;66:*.for=38;5;81:*.fp7=38;5;60:*.frag=38;5;136:*.ftn=38;5;81:*.fvd=38;5;202:*.fxml=38;5;178:*.gb=38;5;213:*.gba=38;5;213:*.gbc=38;5;213:*.gbr=38;5;7:*.gel=38;5;213:*.gemspec=38;5;41:*.ger=38;5;7:*.gg=38;5;213:*.ggl=38;5;213:*.gp3=38;5;115:*.gp4=38;5;115:*.gs=38;5;81:*.hi=38;5;110:*.hidden-color-scheme=38;5;241;3:*.hidden-tmTheme=38;5;241;3:*.hin=38;5;242;3:*.hjson=38;5;178:*.hpp=38;5;110:*.hs=38;5;81:*.htm=38;5;125;1:*.http=38;5;90;1:*.hxx=38;5;110:*.ii=38;5;110:*.iml=38;5;166:*.in=38;5;242;3:*.info=38;5;184:*.ini=1:*.ipa=38;5;215:*.ipk=38;5;213:*.ipynb=38;5;41:*.j64=38;5;213:*.jad=38;5;215:*.jhtm=38;5;125;1:*.jsm=38;5;079;1:*.jsonc=38;5;178:*.jsonl=38;5;178:*.jsonnet=38;5;178:*.jsp=38;5;079;1:*.jsx=38;5;074;1:*.jxl=38;5;97:*.kak=38;5;172:*.key=38;5;166:*.lagda=38;5;81:*.lagda.rst=38;5;81:*.lagda.tex=38;5;81:*.last-run=1:*.lhs=38;5;81:*.libsonnet=38;5;142:*.lisp=38;5;81:*.lnk=38;5;97;5:*.localized=38;5;239:*.localstorage=38;5;60:*.m=38;5;110:*.m2v=38;5;114:*.m3u=38;5;116:*.m3u8=38;5;116:*.m4=38;5;242;3:*.m4a=38;5;137;1:*.m4v=38;5;114:*.map=38;5;7:*.md5=38;5;116:*.mdb=38;5;60:*.mde=38;5;60:*.mdx=38;5;184:*.merged-ca-bundle=1:*.mf=38;5;7:*.mfasl=38;5;7:*.mht=38;5;125;1:*.mi=38;5;7:*.mid=38;5;136;1:*.midi=38;5;136;1:*.mjs=38;5;074;1:*.mkd=38;5;184:*.mkv=38;5;114:*.ml=38;5;81:*.mm=38;5;7:*.mobi=38;5;141:*.mod=38;5;137;1:*.moon=38;5;81:*.mount=38;5;45:*.mpg=38;5;114:*.msg=38;5;178:*.mtx=38;5;7:*.mustache=38;5;135;1:*.mysql=38;5;222:*.nc=38;5;60:*.ndjson=38;5;178:*.nds=38;5;213:*.nes=38;5;213:*.nfo=38;5;184:*.nib=38;5;57:*.nim=38;5;81:*.nimble=38;5;81:*.nix=38;5;155:*.nrg=38;5;202:*.nth=38;5;97:*.numbers=38;5;112:*.o=38;5;241:*.odb=38;5;111:*.odp=38;5;166:*.ods=38;5;112:*.odt=38;5;111:*.oga=38;5;137;1:*.ogg=38;5;137;1:*.ogm=38;5;114:*.ogv=38;5;115:*.opus=38;5;137;1:*.otf=38;5;66:*.pacnew=38;5;33:*.pages=38;5;111:*.pak=38;5;215:*.part=38;5;239:*.patch=38;5;197;3;4:*.path=38;5;45:*.pbxproj=1:*.pc=38;5;7:*.pcap=38;5;29:*.pcb=38;5;7:*.pcf=1:*.pcm=38;5;136;1:*.pdf=38;5;141:*.pfa=38;5;66:*.pfb=38;5;66:*.pfm=38;5;66:*.pgn=38;5;178:*.pgsql=38;5;222:*.pi=38;5;7:*.pid=38;5;248:*.pk3=38;5;215:*.pl=38;5;208:*.plist=1:*.plt=38;5;7:*.ply=38;5;216:*.pm=38;5;203:*.png=38;5;97:*.pod=38;5;184:*.pot=38;5;7:*.pps=38;5;166:*.ppt=38;5;166:*.ppts=38;5;166:*.pptsm=38;5;166;4:*.pptx=38;5;166:*.pptxm=38;5;166;4:*.prisma=38;5;222:*.properties=38;5;116:*.prql=38;5;222:*.ps=38;5;99:*.psd=38;5;97:*.psf=1:*.pug=38;5;135;1:*.pxd=38;5;97:*.pxm=38;5;97:*.qcow=38;5;202:*.rdata=38;5;178:*.rdf=38;5;7:*.rkt=38;5;81:*.rlib=38;5;241:*.rmvb=38;5;114:*.rnc=38;5;178:*.rng=38;5;178:*.rom=38;5;213:*.rss=38;5;178:*.rst=38;5;184:*.rstheme=1:*.rtf=38;5;111:*.s3m=38;5;137;1:*.sample=38;5;114:*.sc=38;5;41:*.scan=38;5;242;3:*.sch=38;5;7:*.scm=38;5;7:*.scpt=38;5;219:*.scss=38;5;105;1:*.sed=38;5;172:*.service=38;5;45:*.sfv=38;5;116:*.sgml=38;5;178:*.sid=38;5;137;1:*.sis=38;5;7:*.sms=38;5;213:*.socket=38;5;45:*.sparseimage=38;5;202:*.spl=38;5;7:*.spv=38;5;217:*.srt=38;5;117:*.ssa=38;5;117:*.st=38;5;213:*.state=38;5;248:*.stderr=38;5;160;1:*.stl=38;5;216:*.storyboard=38;5;196:*.strings=1:*.sty=38;5;7:*.sub=38;5;117:*.sublime-*=1:*.sug=38;5;7:*.sup=38;5;117:*.svelte=38;5;135;1:*.svg=38;5;99:*.swo=38;5;244:*.sx=38;5;81:*.target=38;5;45:*.tdy=38;5;7:*.tfnt=38;5;7:*.tfstate=38;5;168:*.tfvars=38;5;168:*.tg=38;5;7:*.theme=38;5;116:*.tif=38;5;97:*.tiff=38;5;97:*.timer=38;5;45:*.tmTheme=1:*.toast=38;5;202:*.tsv=38;5;78:*.tsx=38;5;074;1:*.ttf=38;5;66:*.twig=38;5;81:*.typelib=38;5;60:*.urlview=38;5;116:*.user-ca-bundle=1:*.v=38;5;81:*.vala=38;5;81:*.vapi=38;5;81:*.vcard=38;5;7:*.vcd=38;5;202:*.vcf=38;5;7:*.vdf=38;5;215:*.vdi=38;5;202:*.vert=38;5;136:*.vfd=38;5;202:*.vhd=38;5;202:*.vhdx=38;5;202:*.vmdk=38;5;202:*.vob=38;5;115;1:*.vpk=38;5;215:*.vtt=38;5;117:*.vue=38;5;135;1:*.wav=38;5;136;1:*.webloc=38;5;116:*.webm=38;5;115:*.webp=38;5;97:*.wgsl=38;5;97:*.woff=38;5;66:*.woff2=38;5;66:*.wrl=38;5;216:*.wv=38;5;136;1:*.wvc=38;5;136;1:*.xcf=38;5;7:*.xcsettings=1:*.xcuserstate=1:*.xcworkspacedata=1:*.xib=38;5;208:*.xla=38;5;76:*.xln=38;5;7:*.xls=38;5;112:*.xlsx=38;5;112:*.xlsxm=38;5;112;4:*.xltm=38;5;73;4:*.xltx=38;5;73:*.xpi=38;5;215:*.xpm=38;5;97:*.xsd=38;5;178:*.xsh=38;5;41:*.z[0-9]{0,2}=38;5;239:*.zig=38;5;81:*.zwc=38;5;241:*.zx[0-9]{0,2}=38;5;239:'
# encrypted files
LS_COLORS+='*.enc=38;5;69;3:*.gpg=38;5;69;3:*.p12=38;5;69;3:*.p7s=38;5;69;3:*.pem=38;5;69;3:*.pgp=38;5;69;3:*.sig=38;5;69;3:*.signature=38;5;69;3:*.asc=38;5;69;3:*.bfe=38;5;69;3:*.current=38;5;69;3:'
# packages
LS_COLORS+='*.apk=38;5;215:*.deb=38;5;215:*.dll=38;5;241:*.dmg=38;5;215:*.rpm=38;5;215:*.war=38;5;215:*.bin=38;5;202:*.iso=38;5;202:*.jar=38;5;215:*.out=38;5;242;3:'
# dump/log
LS_COLORS+='*.bak=38;5;241;3:*.dump=38;5;241;3:*.mdump=38;5;241;3:*.stackdump=38;5;241;3:*.zcompdump=38;5;241;3:*.snapshot=38;5;45:*.swap=38;5;241;3:*.swp=38;5;241;3:*.tmp=38;5;241;3:*.viminfo=1;3:*vim_mru_files=1;3:*.DS_Store=38;5;239;3:*.old=38;5;239;3:*.org=38;5;241;3:*.norg=38;5;241;3:*.orig=38;5;241;3:*.sav=38;5;241;3:*.log=38;5;241;3:*.un~=38;5;241;3:'
# audio/video
LS_COLORS+='*.wma=38;5;137;1:*.wmv=38;5;114:*.JPG=38;5;97:*.MOV=38;5;114:*.ape=38;5;136;1:*.avi=38;5;114:*.bmp=38;5;97:*.gif=38;5;97:*.icns=38;5;97:*.ico=38;5;97:*.ics=38;5;7:*.img=38;5;202:*.jpeg=38;5;97:*.jpg=38;5;97:*.mov=38;5;114:*.mp3=38;5;137;1:*.mp4=38;5;114:*.mp4a=38;5;137;1:*.mpeg=38;5;114:*.torrent=38;5;116:*.ts=38;5;074;1:'
# docs
LS_COLORS+='*AUTHORS=38;5;172;1:*CHANGELOG=38;5;172;1:*CHANGES=38;5;172;1:*CODEOWNERS=38;5;172;1:*CONTRIBUTING=38;5;172;1:*CONTRIBUTORS=38;5;172;1:*COPYING=38;5;172;1:*COPYRIGHT=38;5;172;1:*CodeResources=38;5;239:*Containerfile=38;5;143:*INSTALL=38;5;220;1:*LICENSE=38;5;220;1:*LS_COLORS=38;5;197;1;3;4:*MANIFEST=38;5;243:*[Mm]akefile=38;5;143:*NOTICE=38;5;220;1:*PATENTS=38;5;220;1:*PkgInfo=38;5;239:*README.rst=38;5;172;1:*VERSION=38;5;172;1:*authorized_keys=1;3:*core=38;5;241:*config=1;3:*lock=38;5;248:*lockfile=38;5;248:*pm_to_blib=38;5;264:'
# git
LS_COLORS+='*.git=38;5;133;3:*.gitattributes=38;5;133;3:*.gitignore_global=38;5;60;3:*.gitignore=38;5;60;3:*.github=38;5;133:*.gitmodules=38;5;198;3:'
# system rc
LS_COLORS+='*history=38;5;242;3:*rc=38;5;66;3:*.profile=1;3:*.bash_login=1;3:*.bash_logout=1;3:*.bash_profile=1;3:*.zlogin=1;3:*.zlogout=1;3:*.zprofile=1;3:*.zshenv=1;3:*id_dsa=38;5;192;3:*id_ecdsa=38;5;192;3:*id_ed25519=38;5;192;3:*id_rsa=38;5;192;3:*known_hosts=1;3:*known_hosts.old*=1;3:*cfg=1;3:*conf=1;3:*ignore=38;5;60;3:*ignore_global=38;5;60;3:*.containerignore=38;5;60;3:*.dockerignore=38;5;60;3:'
# program/script
LS_COLORS+='*.bat=38;5;134:*.BAT=38;5;134:*.sh=38;5;143:*.bash=38;5;143:*.fish=38;5;134:*.zsh=38;5;134:*.py=38;5;99:*.pyc=38;5;105:*.go=38;5;81:*.h=38;5;110:*.h++=38;5;110:*.c=38;5;75:*.cc=38;5;75:*.c++=38;5;75:*.cpp=38;5;75:*.cxx=38;5;75:*.tcc=38;5;110:*.r=38;5;143:*.R=38;5;143:*.r[0-9]{0,2}=38;5;239:*.rake=38;5;155:*.rb=38;5;184:*.ahk=38;5;184:*.awk=38;5;184:*.less=38;5;105;1:*.css=38;5;105;1:*.html=38;5;125;1:*.java=38;5;079;1:*.json=38;5;178:*.json5=38;5;178:*.markdown=38;5;134:*.md=38;5;134:*.msql=38;5;222:*.php=38;5;81:*.sass=38;5;105;1:*.sassc=38;5;244:*.swift=38;5;219:*.tcl=38;5;64;1:*.txt=38;5;253:*.vim=38;5;134:*.xml=38;5;178:*.yaml=38;5;178:*.yml=38;5;178:*.vb=38;5;81:*.vba=38;5;81:*.vbs=38;5;81:*.js=38;5;074;1:*.lua=38;5;178:*.rs=38;5;178:*.ru=38;5;7:*.s=38;5;110:*.scala=38;5;114:*.sql=38;5;222:*.sqlite=38;5;60:*.t=38;5;114:*.tex=38;5;184:*.textile=38;5;184:*.tf=38;5;168:*.tfm=38;5;7:*.toml=38;5;178:*[Dd]ockerfile=38;5;143:'
export LS_COLORS

  • way to verify

    # i.e.:
LS_COLORS='bd=38;5;68:ca=38;5;17:cd=38;5;113;1:di=38;5;108:do=38;5;127:ex=38;5;31;1:pi=38;5;126:fi=0:ln=target:mh=38;5;222;1:no=0:or=48;5;196;38;5;232;1:ow=38;5;220;1:sg=48;5;3;38;5;0:su=38;5;220;1;3;100;1:so=38;5;197:st=38;5;86;48;5;234:tw=48;5;235;38;5;139;3:'

# check via
$ echo -e """
  \033[38;5;68m               bd=  \033[0m
  \033[38;5;17m               ca=  \033[0m
  \033[38;5;113;1m            cd=  \033[0m
  \033[38;5;108m              di=  \033[0m
  \033[38;5;127m              do=  \033[0m
  \033[38;5;31;1m             ex=  \033[0m
  \033[38;5;126m              pi=  \033[0m
  \033[38;5;222;1m            mh=  \033[0m
  \033[48;5;196;38;5;232;1m   or=  \033[0m
  \033[38;5;220;1m            ow=  \033[0m
  \033[48;5;3;38;5;0m         sg=  \033[0m
  \033[38;5;220;1;3;100;1m    su=  \033[0m
  \033[38;5;197m              so=  \033[0m
  \033[38;5;86;48;5;234m      st=  \033[0m
  \033[48;5;235;38;5;139;3m   tw=  \033[0m
  """

set dns for ubuntu

$ cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 8.8.8.8
nameserver 8.8.4.4
nameserver 127.0.1.1

$ cat /etc/resolvconf/resolv.conf.d/head
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 8.8.8.8
nameserver 8.8.4.4
$ sudo resolvconf -u

# or
$ cat /etc/dhcp/dhclient.conf | grep "prepend domain-name-servers"
prepend domain-name-servers 8.8.8.8, 8.8.4.4;

# or
$ cat /etc/network/interfaces | grep dns
    dns-nameservers 8.8.8.8 8.8.4.4

disable firewall

$ sudo systemctl stop firewalld
$ sudo systemctl disable firewalld
$ sudo systemctl mask firewalld

  • check result

    $ sudo systemctl is-enabled firewalld
$ sudo systemctl is-active firewalld
$ sudo firewall-cmd --state

off swap

$ sudo swapoff -a
$ sudo bash -c "/usr/bin/sed -e 's:^\\(.*swap.*\\)$:# \\1:' -i /etc/fstab"

disable selinux

$ setenforce 0
$ sudo bash -c "/usr/bin/sed 's/^SELINUX=enforcing$/SELINUX=permissive/' -i /etc/selinux/config"

confined and unconfined users

references:

  • installation

    $ yum -y install setools-console

  • setup for exiting account

    $ semanage login -a -s staff_u <account>

# or
$ semanage login -a -s staff_u -r s0-s0:c0.c100 <account>

  • Modifying an existing mapping

    $ semanage login -m -s sysadm_u <account>

  • delete a mapping

    $ semanage login -d <account>

  • list mappings

    $ semanage user -l

tips

about whatis

$ whatis whois
whois (1)            - client for the whois directory service
$ whatis which
which (1)            - locate a command
$ whatis whereis
whereis (1)          - locate the binary, source, and manual page files for a command

Synchronous system and hardware clock

$ ntpdate pool.ntp.org && hwclock --systohc && hwclock --adjust

backup hard disk timely

$ rsync -a --link-dest=/media/backup/$HOSTNAME/$PREVDATE '--exclude=/[ps][ry][os]' --exclude=/media/backup/$HOSTNAME / /media/backup/$HOSTNAME/$DATE/

service

enable/disable service

$ sudo systemctl enable --now kubelet
Created symlink /etc/systemd/system/multi-user.target.wants/kubelet.service → /etc/systemd/system/kubelet.service
$ sudo systemctl disable --now docker

check service enable or not

$ sudo systemctl is-enabled firewalld
$ sudo systemctl is-active firewalld

  • or

    $ sudo firewall-cmd --state
not running

start/stop service

$ sudo system start <service>
$ sudo system stop <service>

check log

$ journalctl -u docker -f

system encoding

references:

important files:

  • /etc/default/locale

  • /etc/locale.gen

  • /etc/environment

  • /usr/share/locales

  • /var/lib/locales/supported.d/local

  • /usr/local/share/i18n/SUPPORTED

  • /usr/share/i18n/SUPPORTED

setup via environment

$ sudo bash -c 'cat >> /etc/bash.bashrc' << EOF
export LANG=en_US.UTF-8
export LANGUAGE=$LANG
export LC_COLLATE=$LANG
export LC_CTYPE=$LANG
export LC_MESSAGES=$LANG
export LC_MONETARY=$LANG
export LC_NUMERIC=$LANG
export LC_TIME=$LANG
export LC_ALL=$LANG
EOF

$ source /etc/bash.bashrc

  • check locale for account

    $ sudo su -l -c locale <account>

# i.e.:
$ sudo su -l -c locale marslo
LANG=en_US.UTF-8
LC_CTYPE="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_COLLATE="en_US.UTF-8"
LC_MONETARY="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_PAPER="en_US.UTF-8"
LC_NAME="en_US.UTF-8"
LC_ADDRESS="en_US.UTF-8"
LC_TELEPHONE="en_US.UTF-8"
LC_MEASUREMENT="en_US.UTF-8"
LC_IDENTIFICATION="en_US.UTF-8"
LC_ALL=en_US.UTF-8

setup via locale command

$ apt-get install -y locales

$ sudo locale-gen en_US.UTF-8
$ sudo update-locale LANG=en_US.UTF-8
$ source /etc/default/locale

# or
$ sudo dpkg-reconfigure locales

# or
$ sudo localectl set-locale LANG=en_US.UTF-8,LC_ALL=en_US.UTF-8

  • setup environment files

    $ sudo bash -c 'cat >> /etc/environment' << EOF
LANG="en_US.UTF-8"
LANGUAGE="en_US:en:en_US:en"
EOF

locales

CentOS8

installation

references:

locale.conf files support the following environment variables.

  • LANG

  • LANGUAGE

  • LC_ADDRESS

  • LC_COLLATE

  • LC_CTYPE

  • LC_IDENTIFICATION

  • LC_MEASUREMENT

  • LC_MESSAGES

  • LC_MONETARY

  • LC_NAME

  • LC_NUMERIC

  • LC_PAPER

  • LC_TELEPHONE

  • LC_TIME

$ sudo dnf install -y langpacks-en glibc-all-langpacks glibc-langpack-en glibc-langpack-zh
$ sudo localectl set-locale LANG=en_US.UTF-8

# or
$ sudo localectl set-locale LANG=en_US.UTF-8 LANGUAGE=en_US:en:C:es_E

# option
$ sudo localedef -c -f UTF-8 -i en_US en_US.UTF-8

  • check

    $ locale
LANG=en_US.UTF-8
LC_CTYPE="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_COLLATE="en_US.UTF-8"
LC_MONETARY="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_PAPER="en_US.UTF-8"
LC_NAME="en_US.UTF-8"
LC_ADDRESS="en_US.UTF-8"
LC_TELEPHONE="en_US.UTF-8"
LC_MEASUREMENT="en_US.UTF-8"
LC_IDENTIFICATION="en_US.UTF-8"
LC_ALL=en_US.UTF-8

$ localectl status
   System Locale: LANG=en_US.UTF-8
                  LANGUAGE=en_US:en:C:es_ES
       VC Keymap: us
      X11 Layout: us

$ localectl [--no-pager] list-locales

  • more options

    $ yum list available | grep glibc-langpack

get infomation

$ locale -k LC_TIME
$ locale -k LC_TELEPHONE
$ locale -k LC_PAPER

# list all
$ locale -a

# or
$ localedef --list-archive

langpacks

references:

list

$ sudo yum list langpacks-*
$ sudo yum list installed langpacks*
$ sudo yum list available langpacks*
$ sudo yum repoquery --whatsupplements langpacks-<locale_code>

install

$ sudo yum install langpacks-<locale_code>
# i.e.:
$ sudo yum install -y langpacks-en langpacks-en_GB langpacks-zh_CN

# or saving disk space by using glibc-langpack-<locale_code>
$ sudo yum install -y glibc-common glibc-all-langpacks
# or
$ sudo yum install -y *langpacks
# or
$ sudo yum install -y glibc-minimal-langpack
# or
$ sudo yum install -y glibc-langpack-en

  • chinese

    $ sudo yum groupinstall "Chinese Support"

applications

disable lock screen in CentOS 8

  • manually

    • Applications -> Settings -> Poswer Manager -> Display

    • Applications -> Settings -> Screensaver -> Lock Screen

  • cmd

    $ xset s off
$ xset s noblank
# disable the power management using dpms to power monitor down
$ xset -dpms

  • via script

    #!/bin/sh
export DISPLAY=:0.0
xset s off
xset s noblank
xset -dpms

automatically lock the screen when idle

[!NOTE|label:references:]

$ gconftool-2 --type int  --set /desktop/gnome/session/idle_delay 1
$ gconftool-2 --type bool --set /desktop/gnome/lockdown/disable_lock_screen false

sogou Pinyin input method

$ sudo add-apt-repository ppa:fcitx-team/nightly
$ sudo apt-get update
$ sudo apt-get install fcitx-sogoupinyin
$ # sudo apt-get remove ibus

specified terminal size

$ gnome-terminal --geometry=123x42+0+0

burn bootable usb stick

[!NOTE|label:references:]

remove system

[!NOTE|label:references:]

  • remove initrd.img and vmlinuz-*

    $ ls -altrh /boot/vmlinuz-6.2.0-39-generic /boot/initrd.img-6.2.0-39-generic
-rw------- 1 root root 14M Nov 16 01:50 /boot/vmlinuz-6.2.0-39-generic
-rw-r--r-- 1 root root 71M Jan  5 19:58 /boot/initrd.img-6.2.0-39-generic

$ sudo rm -rf /boot/vmlinuz-6.2.0-39-generic /boot/initrd.img-6.2.0-39-generic

  • update grub

    $ sudo update-grub
Sourcing file `/etc/default/grub'
Sourcing file `/etc/default/grub.d/init-select.cfg'
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-6.5.0-14-generic
Found initrd image: /boot/initrd.img-6.5.0-14-generic
Found linux image: /boot/vmlinuz-6.2.0-39-generic
Found initrd image: /boot/initrd.img-6.2.0-39-generic
Memtest86+ needs a 16-bit boot, that is not available on EFI, exiting
Warning: os-prober will not be executed to detect other bootable partitions.
Systems on them will not be added to the GRUB boot configuration.
Check GRUB_DISABLE_OS_PROBER documentation entry.
Adding boot menu entry for UEFI Firmware Settings ...
done

Q&A

yum issue after python upgrade to 3.x

[!NOTE|label:references:]

  • issue

    SyntaxError: invalid syntax
  File "/usr/libexec/urlgrabber-ext-down", line 28
    except OSError, e:
                  ^

  • solution

    $ sed -r '1s/^(.*python)$/\12/g' -i /usr/libexec/urlgrabber-ext-down

    • or change shebang from #! /usr/bin/python to #! /usr/bin/python2

      $ vim /usr/libexec/urlgrabber-ext-down
... change '#! /usr/bin/python' to  '#! /usr/bin/python2'

none of the providers can be installed in dnf upgrade

  • issue

    $ sudo dnf update
...
Last metadata expiration check: 0:01:44 ago on Tue 08 Aug 2023 08:43:40 PM PDT.
Error:
 Problem 1: package authselect-compat-1.1-2.el8.x86_64 requires authselect(x86-64) = 1.1-2.el8, but none of the providers can be installed
  - cannot install both authselect-1.2.2-3.el8.x86_64 and authselect-1.1-2.el8.x86_64
  - cannot install both authselect-1.1-2.el8.x86_64 and authselect-1.2.2-3.el8.x86_64
  - cannot install the best update candidate for package authselect-compat-1.1-2.el8.x86_64
  - cannot install the best update candidate for package authselect-1.1-2.el8.x86_64
 Problem 2: package dbus-x11-1:1.12.8-9.el8.x86_64 requires dbus-daemon = 1:1.12.8-9.el8, but none of the providers can be installed
  - cannot install both dbus-daemon-1:1.12.8-14.el8.x86_64 and dbus-daemon-1:1.12.8-9.el8.x86_64
  - cannot install both dbus-daemon-1:1.12.8-9.el8.x86_64 and dbus-daemon-1:1.12.8-14.el8.x86_64
  - cannot install the best update candidate for package dbus-x11-1:1.12.8-9.el8.x86_64
  - cannot install the best update candidate for package dbus-daemon-1:1.12.8-9.el8.x86_64
 Problem 3: package libstdc++-devel-8.3.1-4.5.el8.x86_64 requires libstdc++(x86-64) = 8.3.1-4.5.el8, but none of the providers can be installed
 ...

  • upgrade bypass issue

    [!NOTE] issue stills exists, but upgrade will be executed successfully

    $ sudo yum upgrade --allowerasing --nobest

Last metadata expiration check: 0:02:43 ago on Tue 08 Aug 2023 08:43:40 PM PDT.
Dependencies resolved.

 Problem 1: cannot install the best update candidate for package cups-client-1:2.2.6-28.el8.x86_64
 ...
 Problem 2: cannot install the best update candidate for package gcc-8.3.1-4.5.el8.x86_64
 ...
 Problem 3: package rpm-libs-4.14.3-19.el8.x86_64 requires liblua-5.3.so()(64bit), but none of the providers can be installed
 ...
 Problem 4: cannot install the best update candidate for package python3-gobject-3.28.3-1.el8.x86_64
 ...
=======================================================================================================================
 Package                                    Arch       Version                              Repository            Size
=======================================================================================================================
Upgrading:
 NetworkManager                             x86_64     1:1.32.10-4.el8                      centos-baseos        2.6 M
 NetworkManager-libnm                       x86_64     1:1.32.10-4.el8                      centos-baseos        1.8 M
 NetworkManager-team                        x86_64     1:1.32.10-4.el8                      centos-baseos        148 k
 NetworkManager-tui                         x86_64     1:1.32.10-4.el8                      centos-baseos        336 k
 ...

  • fix with erase conflict packges permanently

    $ sudo dnf repolist
repo id                                       repo name
baseos                                        CentOS Linux 8 - BaseOS
epel                                          Extra Packages for Enterprise Linux 8 - x86_64
extras                                        CentOS Linux 8 - Extras
jfrog-cli                                     jfrog-cli
mono-centos8-stable                           mono-centos8-stable

$ sudo dnf update --refresh --allowerasing
$ sudo dnf distro-sync -y

ls: Argument list too long

references:

[!NOTE] config files

  • /etc/sysctl.conf

  • /etc/system

  • /etc/security/limits.conf

    #Each line describes a limit for a user in the form:
#
#<domain>        <type>  <item>  <value>
#
#Where:
#<domain> can be:
#        - a user name
#        - a group name, with @group syntax
#        - the wildcard *, for default entry
#        - the wildcard %, can be also used with %group syntax,
#                 for maxlogin limit

  • /etc/limits.conf

  • /etc/security/limits.d/*.conf

    • /etc/security/limits.d/99-nproc-devops.conf

  • all modifications requires logout and login again

    $ sudo pkill -u <username>

check the limit

$ getconf ARG_MAX
2097152

# or
$ echo $(( $(ulimit -s)*1024 / 4 ))
2097152

# check all
$ ulimit -a
core file size          (blocks, -c) unlimited
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 320869
max locked memory       (kbytes, -l) 16384
max memory size         (kbytes, -m) unlimited
open files                      (-n) 1024
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 8192
cpu time               (seconds, -t) unlimited
max user processes              (-u) 320869
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited

# or
$ grep Huge /proc/meminfo
AnonHugePages:     43008 kB
ShmemHugePages:        0 kB
HugePages_Total:       0
HugePages_Free:        0
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB
Hugetlb:               0 kB

  • check page size

    $ cat /proc/sys/vm/nr_hugepages
0
# modify
$ echo 17290 > /proc/sys/vm/nr_hugepages

# or
$ grep Hugepagesize /proc/meminfo
Hugepagesize:       2048 kB

  • grub

    ## centos7
$ grep GRUB_CMDLINE_LINUX /etc/default/grub
GRUB_CMDLINE_LINUX="crashkernel=auto rd.lvm.lv=centos/root rd.lvm.lv=centos/swap rhgb quiet"
# append `default_hugepagesz=1G` to GRUB_CMDLINE_LINUX
GRUB_CMDLINE_LINUX="crashkernel=auto rd.lvm.lv=centos/root rd.lvm.lv=centos/swap rhgb quiet default_hugepagesz=1G"

## centos8
$ grep kernelopts /boot/grub2/grubenv
kernelopts=root=/dev/mapper/rhel-root ro crashkernel=auto resume=/dev/mapper/rhel-swap rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap rhgb quiet
# append default_hugepagesz=1G to kernelopts
kernelopts=root=/dev/mapper/rhel-root ro crashkernel=auto resume=/dev/mapper/rhel-swap rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap rhgb quiet default_hugepagesz=1G

    • rebuid bios & efi

      # for bios booting
$ sudo grub2-mkconfig -o /boot/grub/grub.cfg
# for efi booting
$ sudo grub2-mkconfig -o /boot/efi/EFI/redhat/grub.cfg

setup ulimit

$ ulimit -s
8192

$ ulimit -s 65536
$ ulimit -s
65536

  • via limits.d

    $ cat /etc/security/limits.d/99-nproc-devops.conf
devops soft    nproc    32768
devops soft    nofile 65535

modify open file

# via sysctl
$ sudo sysctl -w fs.file-max=500000
fs.file-max = 500000
$ cat /proc/sys/fs/file-max
500000

# or via sysctl.conf
$ echo 'fs.file-max = 500000' >> /etc/sysctl.conf

# or via ulimit
$ ulimit -Sn 5000
#         |
#         v
#  soft open file
$ ulimit -Hn 50000
#         |
#         v
#  hard open file

# or
$ cat /etc/security/limits.conf
* hard nofile 50000
* soft nofile 5000

setup for particular group

# setup for group `marslo` and `docker`
$ cat /etc/security/limits.conf
...
@marslo   - nofile    65535
@docker   - nofile    65535

others

motd

motd

$ sudo chmod -x /etc/update-motd.d/00-header \
                /etc/update-motd.d/10-help-text \
                /etc/update-motd.d/50-motd-news

$ cat << 'EOF' > /etc/landscape/client.conf
[sysinfo]
exclude_sysinfo_plugins = Temperature, LandscapeLink
EOF

  • motd upgrade disable

    $ sudo mv /etc/update-motd.d/90-updates-available /etc/update-motd.d/org.90-updates-available.org

cockpit

$ sudo systemctl enable --now cockpit.socket
Created symlink /etc/systemd/system/sockets.target.wants/cockpit.socket → /usr/lib/systemd/system/cockpit.socket.

# visit via http://<ip.address>:9090

  • disable

    $ sudo systemctl stop cockpit.socket
$ sudo systemctl disable cockpit.socket

  • motd

    • disable via cockpit-ws

      $ sudo yum remove -y cockpit-ws

    • disable in hard way

      $ sudo ln -sfn /dev/null /etc/motd.d/cockpit

# details
# https://serverok.in/centos-8-disable-activate-the-web-console#comment-35367
$ cat /etc/issue.d/cockpit.issue                // issue shows before login
$ cat /etc/motd.d/cockpit                       // moted shows after login

$ la /etc/motd.d/cockpit
lrwxrwxrwx. 1 root root 17 Mar 15  2021 /etc/motd.d/cockpit -> /run/cockpit/motd
$ la /etc/issue.d/cockpit.issue
lrwxrwxrwx. 1 root root 17 Mar 15  2021 /etc/issue.d/cockpit.issue -> /run/cockpit/motd
$ la /run/cockpit/motd
lrwxrwxrwx. 1 root root 11 Jan  6 03:11 /run/cockpit/motd -> active.motd
$ la /run/cockpit/active.motd
-rw-r-----. 1 root wheel 80 Jan  6 03:11 /run/cockpit/active.motd

  • package info

 $ sudo yum search cockpit
 cockpit.x86_64 : Web Console for Linux servers

 $ sudo yum list installed | grep cockpit
 cockpit.x86_64                                     251.1-1.el8                                   @baseos
 cockpit-bridge.x86_64                              251.1-1.el8                                   @baseos
 cockpit-packagekit.noarch                          251.1-1.el8                                   @appstream
 cockpit-podman.noarch                              33-1.module_el8.5.0+890+6b136101              @appstream
 cockpit-storaged.noarch                            251.1-1.el8                                   @appstream
 cockpit-system.noarch                              251.1-1.el8                                   @baseos
 cockpit-ws.x86_64                                  251.1-1.el8                                   @baseos

 $ rpm -ql cockpit-ws.x86_64
 /etc/cockpit
 /etc/cockpit/ws-certs.d
 /etc/issue.d/cockpit.issue
 /etc/motd.d/cockpit                 // for moted
 /etc/pam.d/cockpit
 ...
PrevioustroubleshootingNextapt/yum/snap

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