Git Cheat Sheet

Find Useful Git commands in this Git Cheat Sheet.

  • Clone a project:
    git clone git_repo_url project_name
  • Switch to a branch locally:
    git checkout branch_name
  • Modify a file, then save and push it to remote repo in current branch
    git add path_to_file_modifeid/file_name
    git commit -m “Description of modification”
    git push
  • Get a new version of a file after modifying local version
    git checkout path_to_file_modified/file_modified
  • Get latest version of current branch
    git fetch
    git pull
    if you have local changes, you will be prompted to commit or stash them before pulling.
  • Create a new branch based on current branch and switch to it
    git checkout –b branch_name
  • Switch to master branch
    git checkout master
  • Merge branch_name to master
    git merge branch_name
  • Delete local branch
    git branch -d branch_name
  • Undo a merge or pull
    git reset –hard
  • Undo a commit locally and on the remote branch
    git reset –hard commit_id
    git push –force
  • Get remote url of a local branch
    git remote show origin


Script with hash tables on windows and Linux

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

  • Hash tables with powershell on windows

    $states=@{“Alberta” = “Calgary”; “British Columbia” = “Vancouver”; “Ontario” = “Toronto” ; “Quebec” = “Montreal”}

    Alberta Calgary
    British Columbia Vancouver
    Ontario Toronto
    Quebec Montreal

    Add new key-value in hashtable:

    Remove key-value in hashtable:
    Change value in hashtable:
    Retrieve value in hashtable:
    Find key in hashtable:
    Find Value in hashtable:
    Count items in hashtable:
    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

    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.
    dict = {‘Name’: ‘Zara’, ‘Age’: 7, ‘Class’: ‘First’}
    Accessing Values
    print “dict[‘Name’]: “, dict[‘Name’]
    print “dict[‘Age’]: “, dict[‘Age’]
    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

    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



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

  • On Windows via batch

    Dir | findstr “filename”

reverse a string on Linux and Windows

How to reverse a string on Linux and Windows

Via shell script on Linux

reverse a string on Linux and Windows

sh-3.2# vi
#### Start Script #####

for (( i=$input_string_length-1; i>=0; i– ))

2022 AWS Cloud Practitioner Exam Preparation

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

Let’s run it:

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

Via powershell script on Windows

#Let’s use the script reverse.ps1 below.
$string_array=$string -split “”
$string_array -join ”

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

E t i e n n e


Via powershell script on Windows in one line

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

Save 65% on select product(s) with promo code 65ZDS44X on

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
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”


List only regular file names in a directory

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

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

    2022 AWS Cloud Practitioner Exam Preparation