Add specific disks in dstat output

Posted on 23/12/202123/12/2021 by Bian Xi Leave a Comment

Add specific disks in dstat output

dstat

dstat is a command to monitor current system performance.

Install

apt install dstat

Add specific disks

dstat -D total,sda,sdb

References

dstat(1) - Linux man page
Linux commands for measuring disk activity

Create LABEL for filesystems in Linux

Posted on 05/11/202106/11/2021 by Bian Xi Leave a Comment

Create LABEL for filesystems in Linux

LABEL is used in /etc/fstab and system boot, such as cmdline.txt and grub, to allow the mounting identify the filesystem..

In order to allow system recognize the LABEL, blkid needs to show the filesystem has the LABEL.

Assign LABEL during filesystem creation

vfat

mkfs.vfat -n "label" /dev/XXX

ext4

mkfs.ext4 -L "label" /dev/XXX

btrfs

mkfs.btrfs -L "label" /dev/XXX

Change LABEL

LABEL can be changed after filesystem created.

swap

swaplabel -L "new label" /dev/XXX using util-linux

ext2/3/4

e2label /dev/XXX "new label" using e2fsprogs

btrfs

btrfs filesystem label /dev/XXX "new label" using btrfs-progs

reiserfs

reiserfstune -l "new label" /dev/XXX using reiserfsprogs

jfs

jfs_tune -L "new label" /dev/XXX using jfsutils

xfs

xfs_admin -L "new label" /dev/XXX using xfsprogs

fat/vfat

fatlabel /dev/XXX "new label" using dosfstools
mlabel -i /dev/XXX ::"new label" using mtools

exfat

tune.exfat -L "new label" /dev/XXX using exfatprogs
exfatlabel /dev/XXX "new label" using exfatprogs or exfat-utils

ntfs

ntfslabel /dev/XXX "new label" using ntfs-3g

udf

udflabel /dev/XXX "new label" using udftools

crypto_LUKS (LUKS2 only)

cryptsetup config --label="new label" /dev/XXX using cryptsetup

References

Persistent block device naming
How do I change the "label" reported by lsblk? [duplicate]

Overlay Filesystem Basic

Posted on 04/11/202104/11/2021 by Bian Xi Leave a Comment

Overlay Filesystem Basic

Overlay filesystem merges lower and upper directories into merged directory.

Mount writable

mount -t overlay overlay -o lowerdir=/lower1:/lower2:/lower3,upperdir=/upper,workdir=/work /merged

The above example will have the order:

/upper
/lower1
/lower2
/lower3

The lower directory can be read-only or could be an overlay itself.
The upper directory is normally writable.
The work directory is used to prepare files as they are switched between the layers, it needs to be an empty directory on the same filesystem mount as the upper directory.
All changes in the merged directory are still reflected in upper.
New files created in lower and upper will be shown in merged.
All files before opened directory, the content is still mapped according to layer.
All files after opened in merged directory, the content will not be reflected in merged directory.

Mount read-only

To mount as read only, no upper and work directory are required.

mount -t overlay overlay -o lowerdir=/lower1:/lower2 /merged

Whiteout files

Whiteout is to simulate a file removed from upper layer directory. It is created as a character device with 0/0 device number.

Opaque directories

Opaque is to simulate a directory removed from upper layer directory. It is made by setting the xattr “trusted.overlay.opaque” to “y”.

References

Overlay filesystem
Overlay Filesystem
Explaining OverlayFS – What it Does and How it Works

Snap Basic

Posted on 01/11/202101/11/2021 by Bian Xi Leave a Comment

Snap Basic

To check the snap utility version, you need to use snap --version command as shown below.

Basic Commands

snap install <snap_name>
snap remove <snap_name>
snap remove <snap_name> --purge       # No snapshot generated
snap list
snap list --all
snap info <snap_name>
snap find <snap_name>
snap revert <snap_name>
snap enable <snap_name>
snap disable <snap_name>
snap download <snap_name>

Snap updates

snap refresh <snap_name>
snap refresh --list

Snap Channels (releases)

They are stable, edge, beta and candidate.

# snap install --edge <snap_name>
# snap install --beta <snap_name>
# snap install --candidate <snap_name>

Snap Changes

snap changes

Snap Connections

snap connections <snap_name>

Snap Model/Version

snap model
snap --version

Snap Service

snap services lxd
snap restart lxd
snap stop lxd
snap start lxd
snap logs lxd

Snap Alias

snap alias <snap_name> <alias_name>
snap aliases
snap unalias <alias_name>

Snap Snapshot

snap save
snap check-snapshot <snapshot_num>
snap restore <snapshot_num>
snap forget <snapshot_num>        # Delete a snapshot
snap saved
snap saved --id=<snapshot_num>        # View a snapshot

Snap login

snap login
snap logout

Snap Config

snap set system refresh.retain=2
snap get system refresh.retain
snap unset system refresh.retain

References

Options restrict in one filesystem

Posted on 23/10/2021 by Bian Xi Leave a Comment

Options restrict in one filesystem

There are quite number of tasks may want to be executed in one filesystem, this is important during troubleshooting, especially for root directory (/).

find

Restrict find command only looking entries within one filesystem, use option -xdev

find /usr -xdev ...

du

Restrict du command only calculate for one filesystem, use option -x

du -cshx /

tar

Restrict tar command only archive files in one filesystem, use option --one-file-system

tar --one-file-system -czvf /tmp/root.tgz /

Process Listening on a Particular Port in Linux

Posted on 15/10/202115/10/2021 by Bian Xi Leave a Comment

Process Listening on a Particular Port in Linux

These commands might not workable in some Unix like systems.

Using netstat

netstat -ltnp
netstat -peanut

lsof

lsof -i :80

fuser

fuser 80/tcp

ss


ss -nlp
``

## References

[3 Ways to Find Out Which Process Listening on a Particular Port](https://www.tecmint.com/find-out-which-process-listening-on-a-particular-port/)

Remove empty directories recursively

Posted on 08/10/202108/10/2021 by Bian Xi Leave a Comment

Remove empty directories recursively

Use `find` command

Use following command can remove empty directories which may have empty directories in them. The -depth will sort the output according to the depth of directories.

find . -type d -depth -exec rmdir {} \;

Note: Just ignore error due to directory not empty

Use `rmdir` command

First, need to know how deep of your directory, then can run following command

rmdir */*/*/*
rmdir */*/*
rmdir */*
rmdir *

Note: This can cause too many arguments error or command line too long error for large directory.

Find hardware info in Linux

Posted on 05/10/2021 by Bian Xi Leave a Comment

Find hardware info in Linux

motherboard info:

Basic info

sudo dmidecode -t 2
lshw

Detail info

sudo dmidecode | less

PCI info

lspci

USB info

lsusb

proc

cat /sys/devices/virtual/dmi/id/board_{vendor,name,version}

dmesg

dmesg | grep DMI:

GUI

hardinfo
cpu-g
lshw-gtk
PerlMon

TODO: Cannot set LC_CTYPE/LC_ALL to default locale: No such file or directory

Posted on 27/09/202127/09/2021 by Bian Xi Leave a Comment

Cannot set LC_CTYPE/LC_ALL to default locale: No such file or directory

Error description

Below error repeatly appears when run apt upgrade.

perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
    LANGUAGE = (unset),
    LC_ALL = (unset),
    LC_CTYPE = "UTF-8",
    LANG = "en_US.UTF-8"
    are supported and installed on your system.
perl: warning: Falling back to a fallback locale ("en_US.UTF-8").
Scanning processes...
Scanning candidates...
Scanning linux images...
/usr/bin/locale: Cannot set LC_CTYPE to default locale: No such file or directory
/usr/bin/locale: Cannot set LC_ALL to default locale: No such file or directory

Check /etc/default/locale file,

#  File generated by update-locale
LANG=en_US.UTF-8

it doesn't contain following lines

LC_CTYPE="en_US.UTF-8"
LC_ALL="en_US.UTF-8"

Tried but failed

Tried to run following commands, the errors are still there.

locale-gen "en_US.UTF-8"
dpkg-reconfigure locales

Also added following lines in /etc/environment and /etc/default/locale, still failed

LC_ALL=en_US.UTF-8
LANG=en_US.UTF-8

Docker Compose – wordpress

Posted on 23/09/202125/09/2021 by Bian Xi Leave a Comment

Docker Compose - wordpress

Simple steps to start using docker compose to create wordpress dockers.

Installation

Install `docker-compose` package

Run following command on ubuntu and armbian servers.

apt install docker-compose

Create dockers

Create folder as project name `wp`

The project name will be used as a part of docker container name.

mkdir -p /app/wp

Create docker compose file

Using vi to create file docker-compose.yml in directory /app/wp

version: "3.3"

services:
  db:
    image: mariadb:latest
    volumes:
      - db_data:/var/lib/mysql
    ports:
      - "3306:3306"
    restart: always
    environment:
      MYSQL_ROOT_PASSWORD: somewordpress
      MYSQL_DATABASE: wordpress
      MYSQL_USER: wordpress
      MYSQL_PASSWORD: wordpress

  wordpress:
    depends_on:
      - db
    image: wordpress:latest
    volumes:
      - wordpress_data:/var/www/html
    ports:
      - "80:80"
    restart: always
    environment:
      WORDPRESS_DB_HOST: db:3306
      WORDPRESS_DB_USER: wordpress
      WORDPRESS_DB_PASSWORD: wordpress
      WORDPRESS_DB_NAME: wordpress
volumes:
  db_data: {}
  wordpress_data: {}

Run docker compose command

docker-compose up -d

Destroy dockers

Run docker compose command

docker-compose down

Destroy dockers and their volumes

docker-compose down --volumes

M	T	W	T	F	S	S
		1	2	3	4	5
6	7	8	9	10	11	12
13	14	15	16	17	18	19
20	21	22	23	24	25	26
27	28	29	30	31

Category: linux

Add specific disks in dstat output

dstat

Install

Add specific disks

References

Create LABEL for filesystems in Linux

Assign LABEL during filesystem creation

vfat

ext4

btrfs

Change LABEL

swap

ext2/3/4

btrfs

reiserfs

jfs

xfs

fat/vfat

exfat

ntfs

udf

crypto_LUKS (LUKS2 only)

References

Overlay Filesystem Basic

Mount writable

Mount read-only

Whiteout files

Opaque directories

References

Snap Basic

Basic Commands

Snap updates

Snap Channels (releases)

Snap Changes

Snap Connections

Snap Model/Version

Snap Service

Snap Alias

Snap Snapshot

Snap login

Snap Config

References

Options restrict in one filesystem

find

du

tar

Process Listening on a Particular Port in Linux

Using netstat

lsof

fuser

ss

Remove empty directories recursively

Use find command

Use rmdir command

Find hardware info in Linux

motherboard info:

Basic info

Detail info

PCI info

USB info

proc

dmesg

GUI

Cannot set LC_CTYPE/LC_ALL to default locale: No such file or directory

Error description

Tried but failed

Docker Compose - wordpress

Installation

Install docker-compose package

Create dockers

Create folder as project name wp

Create docker compose file

Run docker compose command

Destroy dockers

Run docker compose command

Destroy dockers and their volumes

Use `find` command

Use `rmdir` command

Install `docker-compose` package

Create folder as project name `wp`