A

Alternatives

• alternatives --list: list all alternatives

Change python version

sudo update-alternatives --install /usr/bin/python python /usr/bin/python3.9 1
sudo update-alternatives --install /usr/bin/python python /usr/local/bin/python3.12 2
sudo update-alternatives --config python
# Then select number of version to be used

• Another option is using ln: sudo ln -sf /usr/local/bin/python3.12 /usr/bin/python

Asar

• An ASAR file is an archive used to package source code for an application using Electron, an open source library used to build cross-platform programs. It is saved in a format similar to .TAR archives where files contained in the archive, such as .HTML, .JS, and .CSS files, are concatenated together without using compression.

To extract

• Install NPM: sudo apt install npm

• Install asar using npm: npm install -g asar

  • -g: install to global mode

  • default is local which is current project directory

• Extract all files: asar extract <archive.asar>

• Extract one file from archive: asar extract-file

Resource

• https://fileinfo.com/extension/asar

AWK

Arithmetic Expressions

Operator	Type	Meaning	Examples
+	Arithmetic	Addition	7 + 3 = 10
–	Arithmetic	Subtraction	7 – 3 = 4
*	Arithmetic	Multiplication	7 * 3 = 21
/	Arithmetic	Division	7 / 3 = 2.33333
%	Arithmetic	Modulo	7 % 3 = 1
	String	Concatenation	7 3 = 73

Autoincrement and autodecrement operators

• x++

• –y

Assignment Operators

Operator	Meaning
+=	Add result to variable
-=	Subtract result from variable
*=	Multiply variable by result
/=	Divide variable by result
%=	Apply modulo to variable

Conditional expressions

Operator	Meaning
==	Is equal
!=	Is not equal to
>	Is greater than
>=	Is greater than or equal to
<	Is less than
<=	Is less than or equal to

• These operators can be used to compare numbers or strings

• With strings, lower case letters are greater than upper case letters

• A value of 0 is false, anything else is true

• Undefined variables has the value of 0

Regular Expressions

Operator	Meaning Examples
~	Matches number ~ /(one
!~	Doesn’t match word !~ /hello/

Sample Scripts

Extract lines and sublines

samplerule.csv
number, name
99, Some keyword
100, ABC <some words>
100.1, ABC
100.2, <some words>
101, DEF <some words>


AWK Script
awk -F";" -v parentrule="" 'BEGIN{print "===START==="}; $2 ~ /ABC/ || $1 ~ parentrule {split($1,array,".");parentrule=array[1]; print $0;}; END{ print "\n===END===\n";}' samplerule.csv

Explanation
-F";": Field separator
-v parentrule="": assign variable
$2: column 2
$1: column 1
split($1,array,"."): split column one based on ., assign to array

Combine lines

# Sample Data
Device:!    type is 1000base-T
Device:!    serial number is LDKAFJDLDDD
Device:!    type is 1000base-T
Device:!    serial number is FIAUDFYIUSD
Device:!    type is 1000base-T
Device:!    serial number is DAFDDGADGDD
Device:!    type is 1000base-T
Device:!    serial number is DAFGDAGASDD
Device:!    type is 1000base-T
Device:!    serial number is DADFADFDSAF

• Keep the first line intact

• On the second line

  • Replace everything from :! and trailing spaces with comma

  • Removes the text "type is " or "serial number is " from that line

• Combines both line into a single output line

• Result will be

# Sample Data
Device,1000base-T,LDKAFJDLDDD
Device,1000base-T,FIAUDFYIUSD
Device,1000base-T,DAFDDGADGDD
Device,1000base-T,DAFGDAGASDD
Device,1000base-T,DADFADFDSAF

#!/bin/bash

input_file="input.txt"
output_file="output.txt"

awk '
NR % 2 == 1 {
    line1 = $0
    next
}
NR % 2 == 0 {
    # Replace everything before and including ":!" and any trailing spaces with a comma
    sub(/^.*:! *+/, ",")

    # Remove specific phrases
    gsub(/type is |serial number is /, "")

    print line1 $0
}
' "$input_file" > "$output_file"

• Similar to above script but also replace :! and trailing spaces with comma on the first line and remove "type is " as well

#!/bin/bash

input_file="input.txt"
output_file="output.txt"

awk '
NR % 2 == 1 {
    # Replace everything before and including ":!" and any trailing spaces with a comma
    sub(/:! *+/, ",")

    # Remove specific phrases
    gsub(/type is /, "")

    line1 = $0
    next
}
NR % 2 == 0 {
    # Replace everything before and including ":!" and any trailing spaces with a comma
    sub(/^.*:! *+/, ",")

    # Remove specific phrases
    gsub(/type is |serial number is /, "")

    print line1 $0
}
' "$input_file" > "$output_file"

Reference:

https://likegeeks.com/awk-command/ https://www.grymoire.com/Unix/Awk.html