A list of some important Linux commands part 2

A list of some important Linux commands part 2. In part 1 we learn about some basic commands such as cp, adduser, addgroup, arch, cal, date, cat, cd, etc. these all are the basic but important commands for Linux users that everyone should know. Now here is the second part in this we learn about some advanced commands such as dd, find, fmt, free, df, diff, diff3, dir, du, echo, eject, etc. but these commands are slightly on advance end beginners can’t understand all of them. So let’s start

some basic commands in  linux part 2

dd

The dd command in Linux is used for clone one hard disk to another hard disk. The dd command stands for “Disk Duplicator” and used for converting and copying data. This is a very useful and dangerous tool for the Linux operating system. Because it can use in many ways other than cloning of the hard disk. So we learn dd command in a detailed way in upcoming articles. Here the main use of dd command is given below that is the cloning of hard disk.

[email protected]:~# dd if=/dev/sda of=/dev/sdb

df

The df command is used to display the system disk space usage in output.

[email protected]:~# df /dev/sda
Filesystem 1K-blocks Used Available Use% Mounted on
udev 4078324 0 4078324 0% /dev

diff

The diff command is used to compare two file line by line in Linux operating system.

[email protected]:~# diff a.txt b.txt
1,12c1,5
hiii
hello
how are you
what the hell?
i am fine
what about you
What the hell are going on here
I think
Its enough
For today
Rahul
---
good morning
everyone
once again
i am here
with a new article
[email protected]:~#

diff3

The diff3 command is used to compare three files line by line as the name suggests.

[email protected]:~# diff3 a.txt b.txt c.txt
====
1:1,12c
hiii
hello
how are you
what the hell?
i am fine
what about you
What the hell are going on here
I think
Its enough
For today
Rahul
2:1,5c
good morning
everyone
once again
i am here
with a new article
3:1,3c
hii
everyone goodmorning

dir

The dir command is used to list the directory contents. For example

[email protected]:~# dir
Desktop Music Templates Downloads
Documents Pictures satish Videos

dirname

The dirname command strips the last part of a given filename. This command removes the trailing/component from the NAME and prints the remaining portion. If it prints ‘.’ that means the current directory.

[email protected]:~# dirname Desktop/
.
[email protected]:~# dirname Desktop/a.txt
Desktop

dmidecode

The dmidecode command is used to prints the system’s DMI table contents in a human-readable format. This command is also used for getting Hardware information. For example:

[email protected]:~# dmidecode
# dmidecode 3.1
Getting SMBIOS data from sysfs.
SMBIOS 2.5 present.
10 structures occupying 449 bytes.
Table at 0x000E1000.

Handle 0x0000, DMI type 0, 20 bytes
BIOS Information
Vendor: innotek GmbH
Version: VirtualBox
Release Date: 12/01/2006
Address: 0xE0000
Runtime Size: 128 kB
ROM Size: 128 kB
Characteristics:
ISA is supported
PCI is supported
Boot from CD is supported
Selectable boot is supported
8042 keyboard services are supported (int 9h)
CGA/mono video services are supported (int 10h)
ACPI is supported

Handle 0x0001, DMI type 1, 27 bytes
System Information
Manufacturer: innotek GmbH
Product Name: VirtualBox
Version: 1.2
Serial Number: 0
UUID: 0E321BAC-7BA8-42F9-8DC0-599A50AF29F9
Wake-up Type: Power Switch
SKU Number: Not Specified
Family: Virtual Machine
Handle 0x0008, DMI type 2, 15 bytes
Base Board Information
Manufacturer: Oracle Corporation
Product Name: VirtualBox
Version: 1.2
Serial Number: 0
Asset Tag: Not Specified
Features:
Board is a hosting board
Location In Chassis: Not Specified
Chassis Handle: 0x0003
Type: Motherboard
Contained Object Handles: 0

Handle 0x0003, DMI type 3, 13 bytes
Chassis Information
Manufacturer: Oracle Corporation
Type: Other
Lock: Not Present
Version: Not Specified
Serial Number: Not Specified
Asset Tag: Not Specified
Boot-up State: Safe
Power Supply State: Safe
Thermal State: Safe
Security Status: None

Handle 0x0007, DMI type 126, 42 bytes
Inactive

Handle 0x0005, DMI type 126, 15 bytes
Inactive

Handle 0x0006, DMI type 126, 28 bytes
Inactive

Handle 0x0002, DMI type 11, 7 bytes
OEM Strings
String 1: vboxVer_5.2.4
String 2: vboxRev_119785

Handle 0x0008, DMI type 128, 8 bytes
OEM-specific Type
Header and Data:
80 08 08 00 BE 61 29 00

Handle 0xFEFF, DMI type 127, 4 bytes
End Of Table

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du

The du command is used to displays the disk usages of files which is present in a directory as well as its sub-directories. For example:

[email protected]:~# du
8 ./.config/evolution/sources
12 ./.config/evolution
4 ./.config/goa-1.0
4 ./.config/systemd/user/sockets.target.wants
4 ./.config/systemd/user/default.target.wants
12 ./.config/systemd/user
16 ./.config/systemd
4 ./.config/enchant
8 ./.config/dconf
8 ./.config/gedit
4 ./.config/ibus/bus
8 ./.config/ibus
4 ./.config/gnome-session/saved-session
8 ./.config/gnome-session
84 ./.config/pulse
8 ./.config/nautilus
172 ./.config
4 ./Downloads
44 ./.vnc
4 ./Music
4 ./Pictures
624 ./.cache/gnome-software/3.26/extensions
96 ./.cache/gnome-software/3.26/ratings
724 ./.cache/gnome-software/3.26
728 ./.cache/gnome-software
936 ./.cache/gstreamer-1.0
4 ./.cache/evolution/sources/trash
8 ./.cache/evolution/sources
4 ./.cache/evolution/addressbook/trash
8 ./.cache/evolution/addressbook
4 ./.cache/evolution/calendar/trash
8 ./.cache/evolution/calendar
4 ./.cache/evolution/mail/trash
8 ./.cache/evolution/mail
4 ./.cache/evolution/memos/trash
8 ./.cache/evolution/memos
4 ./.cache/evolution/tasks/trash
8 ./.cache/evolution/tasks
52 ./.cache/evolution
4 ./.cache/obexd
4 ./.cache/folks/avatars
8 ./.cache/folks
9176 ./.cache/tracker
4 ./.cache/gnome-calculator
60 ./.cache/thumbnails/large
64 ./.cache/thumbnails
4 ./.cache/libgweather
10996 ./.cache
4 ./.gconf
4 ./Templates
4 ./Videos
4 ./.gnupg/private-keys-v1.d
8 ./.gnupg
24 ./Desktop/rahl
32 ./Desktop
4 ./Public
4 ./Documents
4 ./.local/share/evolution/addressbook/trash
4 ./.local/share/evolution/addressbook/system/photos
92 ./.local/share/evolution/addressbook/system
100 ./.local/share/evolution/addressbook
4 ./.local/share/evolution/calendar/trash
8 ./.local/share/evolution/calendar/system
16 ./.local/share/evolution/calendar
4 ./.local/share/evolution/mail/trash
8 ./.local/share/evolution/mail
4 ./.local/share/evolution/memos/trash
8 ./.local/share/evolution/memos
4 ./.local/share/evolution/tasks/trash
8 ./.local/share/evolution/tasks
144 ./.local/share/evolution
8 ./.local/share/gnome-shell
4 ./.local/share/sounds
12 ./.local/share/keyrings
4 ./.local/share/applications
76 ./.local/share/gvfs-metadata
4 ./.local/share/folks
436 ./.local/share/tracker/data
440 ./.local/share/tracker
4 ./.local/share/nautilus/scripts
8 ./.local/share/nautilus
4 ./.local/share/gnome-settings-daemon
988 ./.local/share/app-info/xmls
992 ./.local/share/app-info
4 ./.local/share/icc
1712 ./.local/share
1716 ./.local
13060 .

echo

The echo command is used to display the content as output which is given to it as an input text. For example:

[email protected]:~# echo hello dear
hello dear

eject

The eject command is used to eject the removable disk such as floppy disk, and CD ROM.

[email protected]:~# eject

env

The env command is used to print a list of the current environment variables, or to run another program in a custom environment without modifying the current one.

[email protected]:~# env
LS_COLORS=rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:mi=00:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:st=37;44:ex=01;32:*.tar=01;
31:*.tgz=01;31:*.arc=01;31:*.arj=01;31:*.taz=01;31:*.lha=01;31:*.lz4=01;31:*.lzh=01;31:*.lzma=01;31:*.tlz=01;31:*.txz=01;31:*.tzo=01;31:*.t7z=01;31:*.zip=01;31:*.z=01;31:*.Z=01;31:
*.dz=01;31:*.gz=01;31:*.lrz=01;31:*.lz=01;31:*.lzo=01;31:*.xz=01;31:*.zst=01;31:*.tzst=01;31:*.bz2=01;31:*.bz=01;31:*.tbz=01;31:*.tbz2=01;31:*.tz=01;31:*.deb=01;31:*.rpm=01;31:*.jar=01;
31:*.war=01;31:*.ear=01;31:*.sar=01;31:*.rar=01;31:*.alz=01;31:*.ace=01;31:*.zoo=01;31:*.cpio=01;31:*.7z=01;31:*.rz=01;31:*.cab=01;31:*.wim=01;31:*.swm=01;31:*.dwm=01;31:*.esd=01;31:*.jpg=01;
35:*.jpeg=01;35:*.mjpg=01;35:*.mjpeg=01;35:*.gif=01;35:*.bmp=01;35:*.pbm=01;35:*.pgm=01;35:*.ppm=01;35:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.tiff=01;35:*.png=01;35:*.svg=01;35:
*.svgz=01;35:*.mng=01;35:*.pcx=01;35:*.mov=01;35:*.mpg=01;35:*.mpeg=01;35:*.m2v=01;35:*.mkv=01;35:*.webm=01;35:*.ogm=01;35:*.mp4=01;35:*.m4v=01;35:*.mp4v=01;35:*.vob=01;35:*.qt=01;35:*.
nuv=01;35:*.wmv=01;35:*.asf=01;35:*.rm=01;35:*.rmvb=01;35:*.flc=01;35:*.avi=01;35:*.fli=01;35:*.flv=01;35:*.gl=01;35:*.dl=01;35:*.xcf=01;35:*.xwd=01;35:*.yuv=01;35:*.cgm=01;35:*.emf=01;35:
*.ogv=01;35:*.ogx=01;35:*.aac=00;36:*.au=00;36:*.flac=00;36:*.m4a=00;36:*.mid=00;36:*.midi=00;36:*.mka=00;36:*.mp3=00;36:*.mpc=00;36:*.ogg=00;36:*.ra=00;36:*.wav=00;36:*.oga=00;36:*.opus=00;36:
*.spx=00;36:*.xspf=00;36:
SSH_CONNECTION=192.168.225.131 21528 192.168.225.211 22
LANG=en_US.UTF-8
S_COLORS=auto
XDG_SESSION_ID=4
USER=root
PWD=/root
HOME=/root
SSH_CLIENT=192.168.225.131 21528 22
SSH_TTY=/dev/pts/0
MAIL=/var/mail/root
TERM=xterm
SHELL=/bin/bash
SHLVL=1
LOGNAME=root
DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/0/bus
XDG_RUNTIME_DIR=/run/user/0
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
_=/usr/bin/env
OLDPWD=/root/Desktop

exit

The exit command is used to close the terminal box.

[email protected]:~# exit

expand

This command is used for copies files to the standard output because expansion will produce the content of the file in output with only tabs changed to spaces.

[email protected]:~# expand a.txt
hiii
hello
how are you
what the hell?
i am fine
what about you
What the hell are going on here
I think
Its enough
For today
Rahul

expr

The expr command is used to evaluate the arithmetic expression. such as if you want to know that the output of 5+4 is what then it can help you.

[email protected]:~# expr 5 + 4
9

factor

The factor command is used to express the prime factors of the input number. for example:

[email protected]:~# factor 544
544: 2 2 2 2 2 17

fgrep

This command is used for searching a string instead of searching for a pattern that matches an expression in a file.

[email protected]:~# fgrep "hello" a.txt
hello

find

The find command is used to search any files in a directory as well as in its subdirectories also. For example:

[email protected]:~# find . -name a.txt
./a.txt
./Desktop/a.txt

fmt

This command is a formatter for simplifying and optimizing text files.

[email protected]:~# fmt a.txt
hiii hello how are you what the hell? i am fine what about you What
the hell are going on here I think Its enough For today Rahul

fold

The fold command is used to wrap each input line to fit in specified width. For example:

[email protected]:~# fold -w 12
hi my name is satish meena.
hi my name i
s satish mee
na.

free

The free command is used to display the amount of free memory and used memory in the system. For example:

[email protected]:~# free
total used free shared buff/cache available
Mem: 8182472 771524 6685192 152492 725756 6617384
Swap: 0 0 0

groups

The groups command is used to displays the name of the groups a user is part of.

[email protected]:~# groups
root

gzip

The gzip command is used to compress the input file and replace the input file itself with having a .gz extension.

[email protected]:~# gzip b.txt

gunzip

The gunzip command is used to restore the compressed file into their original form.

[email protected]:~# gunzip b.txt.gz

head

The head command is used to displays the only first ten lines of the file to standard output. For example:

Sample output of a file is given below.

[email protected]:~# cat a.txt
hiii
hello
how are you
what the hell?
i am fine
what about you
What the hell are going on here
I think
Its enough
For today
Rahul
peanut

The output of the file after using the head command. Here you can observe that only the first 10 lines are shown as the output of the file.

[email protected]:~# head a.txt
hiii
hello
how are you
what the hell?
i am fine
what about you
What the hell are going on here
I think
Its enough
For today

THAT’S IT

These are some basic but important commands for Linux users that everyone should know about them. If you want to add some other commands then use the comment box for your thoughts.

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