Shell Script Archives - IT - Engineering - Cloud

January 9, 2019January 3, 2023

Count all http response status codes in a web application log files on linux

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Count all http response status codes in a web application log files on linux

Here is one way to count all the HTTP response status codes in a web application log file on Linux:

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Open the log file using the cat command:

cat log_file

Use the grep command to search for lines that contain an HTTP status code:

cat log_file | grep -Eo 'HTTP/[0-9\.]+ [0-9]+'

This will output all the lines in the log file that contain an HTTP status code.

Use the awk command to extract the status code from each line:

cat log_file | grep -Eo 'HTTP/[0-9\.]+ [0-9]+' | awk '{print $2}'

This will output a list of all the status codes in the log file.

Use the sort and uniq commands to count the number of occurrences of each status code:

cat log_file | grep -Eo 'HTTP/[0-9\.]+ [0-9]+' | awk '{print $2}' | sort | uniq -c

1- Sample Log file:

Given the log file below, we want to know all http response status code and sort them from the highest amount of response code to the lowest.

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2- Use this command below to Count all http response status codes in a web application log files on linux:

awk '{print $9}' sample_log.log | sort | uniq -c | sort -rn

3- Output

Count Each unique Response Status Code from Web App log file

Learn more about http response status code here

July 21, 2016January 3, 2023

Script with hash tables on windows and Linux

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How to declare and write a script with hash tables on windows and linux

A hash table, also known as a hash map, is a data structure that is used to store key-value pairs. It is an efficient way to store data that can be quickly retrieved using a unique key.

Here is an example of how to declare and write a script with a hash table in Python:

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# Declare an empty hash table
hash_table = {}

# Add some key-value pairs to the hash table
hash_table[‘key1’] = ‘value1’
hash_table[‘key2’] = ‘value2’
hash_table[‘key3’] = ‘value3’

# Access a value using its key
print(hash_table[‘key2’]) # Output: “value2”

# Modify a value using its key
hash_table[‘key2’] = ‘new value’
print(hash_table[‘key2’]) # Output: “new value”

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# Delete a key-value pair using the `del` statement
del hash_table[‘key1’]

# Check if a key is in the hash table using the `in` operator
print(‘key1’ in hash_table) # Output: False

 # Output: False

In this example, we declare an empty hash table using the {} syntax. We then add some key-value pairs to the hash table using the [] syntax. We access a value using its key, modify a value using its key, delete a key-value pair using the del statement, and check if a key is in the hash table using the in operator.

I hope this helps! Let me know if you have any questions.

- Hash tables with powershell on windows
  
  Declaration:
  $states=@{“Alberta” = “Calgary”; “British Columbia” = “Vancouver”; “Ontario” = “Toronto” ; “Quebec” = “Montreal”}
  
  Name
  _____ Value
  _______
  
  Alberta Calgary
  
  British Columbia Vancouver
  
  Ontario Toronto
  
  Quebec Montreal
  
  Add new key-value in hashtable:
  $states.Add(“Manitoba”,”Winnipeg”)
  
  Remove key-value in hashtable:
  $states.Remove(“Manitoba”,”Winnipeg”)
  Change value in hashtable:
  $states.Set_Item(“Ontario”,”Ottawa”)
  Retrieve value in hashtable:
  $states.Get_Item(“Alberta”)
  Find key in hashtable:
  $states.ContainsKey(“Alberta”)
  Find Value in hashtable:
  $states.ContainsValue(“Calgary”)
  Count items in hashtable:
  $states.Count
  Sort items by Name in hashtable:
  $states.GetEnumerator() | Sort-Object Name -descending
  Sort items by Value in hashtable:
  $states.GetEnumerator() | Sort-Object Value -descending
- Hash tables with perl on linux or windows
  
  Declaration:
  my %hash = (); #Initialize a hash
  my $hash_ref = {}; # Initialize a hash reference. ref will return HASH
  Clear (or empty) a hash
  for (keys %hash)
  {
  delete $hash{$_};
  }
  Clear (or empty) a hash reference
  for (keys %$href)
  {
  delete $href->{$_};
  }
  Add a key/value pair to a hash
  $hash{ ‘key’ } = ‘value’; # hash
  $hash{ $key } = $value; # hash, using variables
  Using Hash Reference
  $href->{ ‘key’ } = ‘value’; # hash ref
  $href->{ $key } = $value; # hash ref, using variables
  Add several key/value pairs to a hash
  %hash = ( ‘key1’, ‘value1’, ‘key2’, ‘value2’, ‘key3’, ‘value3’ );
  %hash = (
  key1 => ‘value1’,
  key2 => ‘value2’,
  key3 => ‘value3’,
  );
  
  Copy a hash
  my %hash_copy = %hash; # copy a hash
  my $href_copy = $href; # copy a hash ref
  Delete a single key/value pair
  delete $hash{$key};
  delete $hash_ref->{$key};

Hash tables with python on linux or windows

Hash tables are called dictionary in python.
Declaration:
dict = {‘Name’: ‘Zara’, ‘Age’: 7, ‘Class’: ‘First’}
Accessing Values
print “dict[‘Name’]: “, dict[‘Name’]
print “dict[‘Age’]: “, dict[‘Age’]
Output:
dict[‘Name’]: Zara
dict[‘Age’]: 7
Updating Dictionary
dict = {‘Name’: ‘Zara’, ‘Age’: 7, ‘Class’: ‘First’}

dict[‘Age’] = 8; # update existing entry
dict[‘School’] = “DPS School”; # Add new entry
Delete Dictionary Elements
#!/usr/bin/python

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dict = {‘Name’: ‘Zara’, ‘Age’: 7, ‘Class’: ‘First’}

del dict[‘Name’]; # remove entry with key ‘Name’
dict.clear(); # remove all entries in dict
del dict ; # delete entire dictionary

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Source:

https://technet.microsoft.com/en-us/library/ee692803.aspx

http://www.cs.mcgill.ca/~abatko/computers/programming/perl/howto/hash/

http://www.tutorialspoint.com/python/python_dictionary.htm

Posted on July 19, 2016January 3, 2023
How to pipe grep on command line on windows and Linux

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How to pipe grep on command line on Windows and Linux?

Let’s find how to pipe grep or find a specific string after running a command using shell, batch and powershell (windows and Linux)

On Linux via shell

ls -al | grep filename

On Windows via powershell

GetChildItem | Select-Object “filename”
or
GetChildItem | where-Object {$_ -match “filename”}

On Windows via batch

Dir | findstr “filename”

On both Windows and Linux, you can use the grep command in combination with the | (pipe) operator to filter the output of another command. The | operator takes the output of the command on the left and passes it as input to the command on the right.

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Here is an example of how to use the grep command with the | operator on both Windows and Linux:

On Linux:

# List all the files in the current directory and filter the output to show only the files that contain the word "example" ls | grep example

On Windows:

# List all the files in the current directory and filter the output to show only the files that contain the word "example" dir | findstr example

In this example, the ls (Linux) or dir (Windows) command lists all the files in the current directory, and the grep (Linux) or findstr (Windows) command filters the output to show only the lines that contain the word “example”.

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You can use the grep command with the | operator in combination with other command-line utilities to perform various tasks. For example, you can use the grep command to filter the output of the ps command to show only the processes that contain a particular string in their command line arguments.

# Show all the processes that contain the string "python" in their command line arguments ps -aux | grep python

I hope this helps! Let me know if you have any questions.

Posted on September 8, 2015January 3, 2023
reverse a string on Linux and Windows

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How to reverse a string on Linux and Windows

On Linux:

Using the rev command: The rev command is a utility that reverses the lines of a file or the characters in a string. To reverse a string, you can use the echo command to pass the string to rev:

echo "string" | rev

Using the sed command: The sed command is a powerful utility that can perform various text transformations. To reverse a string, you can use the sed command with the -r option and the 's/.*(.)/\1/g' expression:

echo "string" | sed -r 's/.*(.)/\1/g'

Using the awk command: The awk command is a programming language that is used for text processing. To reverse a string, you can use the awk command with the {print} action:

echo "string" | awk '{print $1}'

On Windows:

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Using the powershell command: The powershell command is a shell that provides a command-line interface for Windows. To reverse a string, you can use the powershell command with the -C option and the '[System.Text.Encoding]::Unicode.GetString([System.Text.Encoding]::Unicode.GetBytes("string"))' expression:

powershell -C "[System.Text.Encoding]::Unicode.GetString([System.Text.Encoding]::Unicode.GetBytes("string"))"

Using the cmd command: The cmd command is the command-line interpreter for Windows. To reverse a string, you can use the cmd command with the for loop:

cmd /c "for /L %i in (1,1,%len%) do @echo !string:~%len%-%i,1!"

These are some ways to reverse a string on Linux and Windows. There are other ways to achieve this, using different utilities or programming languages.

Via shell script on Linux

sh-3.2# vi reverse.sh
#### Start Script #####
#!/bin/bash
input_string=”$1″
reverse_string=””

input_string_length=${#input_string}
for (( i=$input_string_length-1; i>=0; i– ))
do
reverse_string=”$reverse_string${input_string:$i:1}”
done

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echo “$reverse_string”
##### End Script #####

Let’s run it:

sh-3.2# chmod 775 reverse.sh
sh-3.2# ./reverse.sh Etienne
enneitE

Via powershell script on Windows

#Let’s use the script reverse.ps1 below.
######
$string=”Etienne”
$string_array=$string -split “”
[array]::Reverse($string_array)
$string_array -join ”

#####Output#####
PS C:\Users\etienne_noumen\Documents\Etienne\Scripting> .\reverse.ps1

E t i e n n e

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enneitE

Via powershell script on Windows in one line

([regex]::Matches($String,’.’,’RightToLeft’) | ForEach {$_.value}) -join ”

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Via batch script on Windows

::Note: ReverseStr also calls StrLen
::and string length is not greater than 80 chars
:: but can be changed.

@echo off
SetLocal EnableDelayedExpansion
cls
set Str=Etienne
call :StrLen %Str%
echo Length=%Len%
call :ReverseStr %Str%
echo String=%Str%
echo Reverse Str=%Reverse%
exit /b

::—————-
:: Calc Var Length
::—————-
:: %*=Str to Check
:: Returns %Len%
:: —————
:StrLen %*
set Data=%*
for /L %%a in (0,1,80) do (
set Char=!Data:~%%a,1!
if not “!Char!”==”” (
set /a Len=%%a+1
) else (exit /b)
)
exit /b

::—————
:: Reverse String
::—————
:: %* Str to Reverse
:: Returns %Reverse%
::——————
:ReverseStr %*
set Data=%*
call :StrLen %Data%
for /L %%a in (!Len!,-1,0) do (
set Char=!Data:~%%a,1!
set Reverse=!Reverse!!Char!
)
exit /b

Via perl script on Windows or Linux

Via python script on Windows or Linux

def reverse_string(a_string)
return a_string[::-1]
reverse_string(“etienne”) returns “enneite”
Source:

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http://www.computing.net/answers/programming/reverse-a-string-in-dos/26004.html

Posted on August 20, 2015April 19, 2016
Remove all empty lines in a file

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How to Remove all empty lines in a file on Linux and Windows?

Remove empty lines from file.txt via Linux command line

Option 1: sed -i ‘/^$/d’ file.txt

Option 2: awk ‘NF > 0’ file.txt > output.txt

Option 3: perl -i.backup -n -e “print if /\S/” file.txt

Option 4: grep . file.txt > output.txt

Remove empty lines from file.txt using Powershell script on Windows

(gc file.txt) | ? {$_.trim() -ne “” } | set-content file.txt

Posted on August 13, 2015April 19, 2016
List only regular file names in a directory

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How to List only regular file names in a directory on Linux and Windows

Listing regular files in a directory without including . and .. files.

On Linux

Solution 1:$ ls -p | grep -v /
Solution 2: $ ls -F | grep -v ‘[/@=|]’
Solution 3: $for list in `ls` ; do ls -ld $list | grep -v ^d > /dev/null && echo $list ; done ;
Solution4:$ for list in `ls` ; do ls -ld $list | grep ^d > /dev/null || echo $list ; done ;
Solution5 (exclude sym links):$ for list in `ls` ; do ls -ld $list | grep -v ^l > /dev/null && echo $list ; done ;

On Windows

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Solution 1: dir /a-d /b >..\File_List.txt

Posted on July 28, 2015July 19, 2016
prompt and read input variables from keyboard

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Let’s find how to prompt and read input variables from keyboard while executing a script using shell, perl, python, batch and powershell (windows and Linux)

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On Linux via shell

read -p “Enter your name: ” name
echo “Hi, $name. Let’s be friend!”

On Windows via powershell

$name=read-host “Enter your name:”
write-host “Hi $name, Let’s be friend!”

On Windows via batch

Set /p Name=”Enter your name:”
echo “Hi %name%, Let’s be friend!”

On Windows or Linux via perl

print “Enter your name “;
my $name = ;
chomp $name; # Get rid of newline character at the end
print “Hello $name, let’s be friend”;

On Windows or Linux via python

name=input(“Enter your name: “)
print (“Hello ” + name + ” let’s be friend”)

Posted on January 29, 2015January 3, 2023
Replace all instances of a string in a file

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How to Replace all instances of a string in a file?

Open the file in read mode using the open() function.

Read the contents of the file into a string using the read() method.

Use the replace() method to replace all instances of the target string with the new string.

Open the file in write mode using the open() function.

Write the modified string to the file using the write() method.

Close the file using the close() method.

Here is an example code snippet:

How to Replace all instances of a string in a file?

This will replace all instances of old_string with new_string in the file file.txt.

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# Open the file in read mode
with open(‘file.txt’, ‘r’) as f:
# Read the contents of the file into a string
contents = f.read()

# Replace all instances of the target string
contents = contents.replace(‘old_string’, ‘new_string’)

# Open the file in write mode
with open(‘file.txt’, ‘w’) as f:
# Write the modified string to the file
f.write(contents)

# Close the file
f.close()

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Shell script to replace all instances of a string in a file on Linux & Windows.

On Linux via bash script

sed “s/$stringToReplace/$replaceWith/g” $File_Name > $File_Name

On Windows using Powershell

( get-content $File_Name ) | % { $_ -replace $stringToReplace, $replaceWith } | set-content $File_Name

On Windows using Batch

set str=teh cat in teh hat
echo.%str%
set str=%str:teh=the%
echo.%str%

Script Output:
teh cat in teh hat
the cat in the hat

On Windows or Linux using Perl

perl -pi.orig -e “s///g;”

On Windows or Linux using Python

Source:

http://stackoverflow.com/questions/60034/how-can-you-find-and-replace-text-in-a-file-using-the-windows-command-line-envir

Posted on January 27, 2015April 20, 2016
Browse the internet via command line

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How to browse the internet via command line on Linux and Windows?

On Linux

lynx http://google.ca
If you don’t have lynx on your linux installation, you will have to install it. On Linux Red hat, install it like this:
yum list lynx (to check the availability of the package)
yum -y install lynx (to install the package)
you can also use: curl -0 http://yoursite/index.html to get the source code of a specific file.

On Windows

start /max http://google.ca
Will open the url using your default browser.

Posted on December 8, 2014January 24, 2023
Check how many CPU cores on Windows and on Linux

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How to check how many CPU cores I have on Windows & Linux?

What is a core in a CPU?
In summary, a core is a small CPU or processor built into a big CPU or CPU socket. It can independently perform or process all computational tasks. From this perspective, we can consider a core to be a smaller CPU or a smaller processor within a big processor.
Today, CPUs have been two and 18 cores, each of which can work on a different task. A core can work on one task, while another core works a different task, so the more cores a CPU has, the more efficient it is.

Open a command prompt (Windows) or Terminal (Linux) and type:

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Windows: WMIC CPU Get /Format:List

Linux: cat /proc/cpuinfo | grep processor | wc -l
For more details on Linux: ls /sys/devices/system/cpu/

What does 4 CPU cores mean?
A quad-core CPU has four processing cores in a single chip. It is similar to a dual-core CPU, but has four separate processors (rather than two), which can process instructions at the same time.

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Name _____	Value _______
Alberta	Calgary
British Columbia	Vancouver
Ontario	Toronto
Quebec	Montreal

How to declare and write a script with hash tables on windows and linux

Hash tables with powershell on windows

Hash tables with perl on linux or windows

Hash tables with python on linux or windows

If you are looking for an all-in-one solution to help you prepare for the AWS Cloud Practitioner Certification Exam, look no further than this AWS Cloud Practitioner CCP CLFC01 book below.

Source:

Let’s find how to pipe grep or find a specific string after running a command using shell, batch and powershell (windows and Linux)

On Linux via shell

On Windows via powershell

On Windows via batch

How to reverse a string on Linux and Windows

Via shell script on Linux

Via powershell script on Windows

If you are looking for an all-in-one solution to help you prepare for the AWS Cloud Practitioner Certification Exam, look no further than this AWS Cloud Practitioner CCP CLFC01 book below.

Via powershell script on Windows in one line

Via batch script on Windows

Via perl script on Windows or Linux

Via python script on Windows or Linux

How to Remove all empty lines in a file on Linux and Windows?

Remove empty lines from file.txt via Linux command line

Remove empty lines from file.txt using Powershell script on Windows

How to List only regular file names in a directory on Linux and Windows

On Linux

On Windows

Let’s find how to prompt and read input variables from keyboard while executing a script using shell, perl, python, batch and powershell (windows and Linux)

On Linux via shell

On Windows via powershell

On Windows via batch

On Windows or Linux via perl

On Windows or Linux via python

How to Replace all instances of a string in a file?

Shell script to replace all instances of a string in a file on Linux & Windows.

On Linux via bash script

On Windows using Powershell

On Windows using Batch

On Windows or Linux using Perl

On Windows or Linux using Python

How to browse the internet via command line on Linux and Windows?

On Linux

On Windows

How to check how many CPU cores I have on Windows & Linux?