git_hacks.sh

# Tl;DR; Don't believe to a git history...
# IMPORTANT: THESE COMMANDS CAN CAUSE DAMAGE, USE IT AT YOUR OWN RISK
# https://git-scm.com/docs/git-filter-branch

git log --all --decorate --oneline --graph
git log --all --decorate --graph --abbrev-commit --pretty=fuller
git log --pretty=format:"%h%x09%an%x09%ae%x09%ai%x09%s%x09%d%n%x09%cn%x09%ce%x09%ci"

# first of all, initialize a git repository
git init
git config user.name "<YOUR_NAME>"
git config user.email <YOUR_EMAIL>
git config push.default simple
git remote add origin <REPO_URL>

#git push origin master
# when first pushing
git push --set-upstream origin master
#git branch --set-upstream-to=origin/master master

# to change an existing remote url
git remote set-url origin <NEW_URL>

### to pull all remote branches
git branch -r | grep -v '\->' | while read remote; do git branch --track "${remote#origin/}" "$remote"; done
git fetch --all
git pull --all


### rewrite old content
####remove content from history (only first level, not recursive into directories!)
git filter-branch --force --tree-filter 'sed -i "s/ .*@gmail\.com//g" *' -- --all
git filter-branch --force --tree-filter 'sed -i "/@gmail\.com/d" *' -- --all
git push origin --force --all
git push origin --force --tags
#### remove files
git filter-branch --force --prune-empty --index-filter 'git rm --cached -r -q -- . ; git reset -q $GIT_COMMIT -- keep_this keep_that_too' -- --all

#git filter-branch --force --prune-empty --subdirectory-filter keep_this_folder -- --all



### change date
date="<TARGET_DATE>"
LC_ALL=C GIT_COMMITTER_DATE="$date" git commit --date "$date"
LC_ALL=C GIT_COMMITTER_DATE="$date" git commit --amend --no-edit --date "$date"


git filter-branch --env-filter \
    'if [ $GIT_COMMIT = <TARGET_COMMIT_HASH> ]
    then
        export GIT_AUTHOR_DATE="<TARGET_DATE>"
        export GIT_COMMITTER_DATE="<TARGET_DATE>"
    fi'

git filter-branch --env-filter '
date="<TARGET_DATE>"
export GIT_AUTHOR_DATE="$date"
export GIT_COMMITTER_DATE="$date"
'

git filter-branch --env-filter '
export GIT_COMMITTER_DATE="$GIT_AUTHOR_DATE"
'


# date -d ${GIT_COMMITTER_DATE%% *}
git filter-branch --force --env-filter \
    'shift=" + 1 day"
    if [ $GIT_COMMIT = <TARGET_COMMIT_HASH> ]
    then
        export GIT_AUTHOR_DATE="$(date --date="$(date --date ${GIT_AUTHOR_DATE%% *})$shift")"
        export GIT_COMMITTER_DATE="$(date --date="$(date --date ${GIT_COMMITTER_DATE%% *})$shift")"
    fi'

# one-liner
git filter-branch --force --env-filter "if test $GIT_COMMIT = '3b0f476ca46d925b37990784f578bad424206e65'; then GIT_AUTHOR_DATE='<TARGET_DATE>'; GIT_COMMITTER_DATE='<TARGET_DATE>'; fi"

# go wild: https://github.com/angusshire/greenhat


### change author and committer
git filter-branch --env-filter '

OLD_EMAIL="<OLD_EMAIL>"
CORRECT_NAME="<NEW_NAME>"
CORRECT_EMAIL="<NEW_EMAIL>"

if [ "$GIT_COMMITTER_EMAIL" = "$OLD_EMAIL" ]
then
    export GIT_COMMITTER_NAME="$CORRECT_NAME"
    export GIT_COMMITTER_EMAIL="$CORRECT_EMAIL"
fi
if [ "$GIT_AUTHOR_EMAIL" = "$OLD_EMAIL" ]
then
    export GIT_AUTHOR_NAME="$CORRECT_NAME"
    export GIT_AUTHOR_EMAIL="$CORRECT_EMAIL"
fi
' --tag-name-filter cat -- --branches --tags

git filter-branch --force --env-filter '
CORRECT_NAME="<NEW_NAME>"
CORRECT_EMAIL="<NEW_EMAIL>"
export GIT_COMMITTER_NAME="$CORRECT_NAME"
export GIT_COMMITTER_EMAIL="$CORRECT_EMAIL"
export GIT_AUTHOR_NAME="$CORRECT_NAME"
export GIT_AUTHOR_EMAIL="$CORRECT_EMAIL"
' --tag-name-filter cat -- --branches --tags