Git

basics

set username and email

source:

to setup your username and email globally use the following commands

git config --global user.name "Max Mustermann"
git config --global user.email "max.mustermann@muster.de"

to setup your username and email for a specific repository use the following commands

cd <path-to-your-repo>/
git config user.name "Max Mustermann"
git config user.email "max.mustermann@muster.de"

store temporarily passwords

source: [git] git-credential-cache

use the git-credential-cache helper

git config credential.helper 'cache --timeout=28800' # 8 hours

rename GitHub branch

source: [GitHub] Renaming a branch

if you need to rename your branch execute the following commands:

git branch -m OLD-BRANCH-NAME NEW-BRANCH-NAME
git fetch origin
git branch -u origin/NEW-BRANCH-NAME NEW-BRANCH-NAME
git remote set-head origin -a

# remove tracking references to the old branch name
git remote prune origin

git tag

source: [Atlassian] Git tag

if you need to create a new tag execute the following commands:

# add annotated tag with message
git tag -a v1.4 -m "my version 1.4"

# push tag to remote
git push origin v1.4

if you need to retag or replace old tags execute the following command

# map commit "15027957951b64cf874c3557a0f3547bd83b3ff6" to tag v1.4 and override existing content for the v1.4 tag
git tag -a -f v1.4 15027957951b64cf874c3557a0f3547bd83b3ff6

delete commit history

source: [Xebia] How to Delete Commit History – A Step-by-Step Guide

if you need to delete your commit history do the following steps

# checkout to a temp branch
git checkout --orphan temp_branch

# add all files
git add -A

# commit
git commit -m "Initial commit"

# delete old branch
git branch -D main

# rename temp branch
git branch -m main

# push
git push --force origin main

encryption with transcrypt

below is a description how to encrypt files in Git with transcrypt
for a working example take a look at the boilerplate repo

initialization

$ cd <path-to-your-repo>/
$ transcrypt

full file encryption

$ cd <path-to-your-repo>/
$ echo 'sensitive content' >> sensitive_file_full
$ echo 'sensitive_file_full filter=crypt diff=crypt merge=crypt' >> .gitattributes
$ git add .gitattributes sensitive_file_full
$ git commit -m 'Add encrypted version of a sensitive file'
$ transcrypt --list
$ transcrypt --show-raw sensitive_file_full

partial file encryption

transcrypt can't encrypt files partially
so I created a workaround based on sed
the file itself is still fully encrypted but a copy of the file will be created which only redacts the sensitive parts

preparation

create a file bin\create-hook-symlinks.sh

#!/bin/bash

for hook in "$(dirname "$0")/../githooks/"*; do
  ln -s -f "../../githooks/$(basename $hook)" "$(dirname "$0")/../.git/hooks/$(basename $hook)"
  echo -e "\n# run $(basename $hook) script" >> "$(dirname "$0")/../.git/hooks/pre-commit"
  echo "\$(dirname \"\$0\")/$(basename $hook)" >> "$(dirname "$0")/../.git/hooks/pre-commit"
done

create a file githooks/pre-commit-sed

#!/usr/bin/env bash
# Pre-commit Hook: Duplicate decrypted sensitive files and redact sensitive information using sed.

set -euo pipefail
IFS=$'\n\t'

# --- Configuration ---
LOG_ENABLED=true              # set to false to disable output

# --- Helper Functions ---
log() {
  if [ "$LOG_ENABLED" = true ]; then
    echo "[redact-hook] $*"
  fi
}

error_exit() {
  echo "[redact-hook] ERROR: $*" >&2
  exit 1
}

# --- Find files with Git attribute 'filter=crypt' ---
mapfile -t secret_files < <(
  git -c core.quotePath=false ls-files \
    | git -c core.quotePath=false check-attr --stdin filter \
    | awk -F':' '/crypt$/{ gsub(/^[ \t]+|[ \t]+$/, "", $1); print $1 }'
)

if [ ${#secret_files[@]} -eq 0 ]; then
  log "No files with 'filter=crypt' found. Skipping."
  exit 0
fi

# --- Process each secret file ---
for secret_file in "${secret_files[@]}"; do
  # skip symlinks
  if [[ -L "$secret_file" ]]; then
    log "Skipping symlink: $secret_file"
    continue
  fi

  dir="$(dirname "$secret_file")"
  filename="$(basename "$secret_file")"
  file_extension="${filename##*.}"
  file_basename="${filename%.*}"

  sed_file="${dir}/${filename}.sed"

  if [[ ! -f "$sed_file" ]]; then
    log "No sed rules found for: $secret_file (expected $sed_file)"
    continue
  fi

  # Determine output name and path
  if [[ "$file_extension" == "$filename" ]]; then
    output_file="${dir}/${file_basename}_dec"
  else
    output_file="${dir}/${file_basename}.${file_extension}.dec"
  fi

  log "Redacting: $secret_file → $output_file"
  sed -f "$sed_file" "$secret_file" > "$output_file" \
    || error_exit "Failed to apply sed rules to $secret_file"
done

log "Redaction complete."

execute file bin/create-hook-symlinks.sh

usage

$ cd <path-to-your-repo>/
$ echo 'user: max mustermann' >> sensitive_file_partial
$ echo 'password: s3nsitive' >> sensitive_file_partial
$ echo 's/\(password: \).*/\1<REDACTED>/' >> sensitive_file_partial.sed
$ echo 'sensitive_file_partial filter=crypt diff=crypt merge=crypt' >> .gitattributes
$ git add .gitattributes sensitive_file_partial
$ git commit -m 'Add encrypted version of a sensitive file'
$ transcrypt --list
$ transcrypt --show-raw sensitive_file_partial

after commit you should see a file sensitive_file_partial_dec where only the password is <REDACTED>