modify date & time of git commit to match its message

modify_date_of_commit.sh

#!/bin/bash

# This script is designed to find the latest Git commit that contains a date, 
# and then change its commit date to a specified date. To achieve this goal, 
# the script performs the following operations:
#
# Use the git log command to find the SHA of the latest Git commit that contains 
# a date.
# Extract the date string from the commit message of the identified commit.
# Convert the date string to a format that Git can accept using the date command 
# with the -d or -j option, depending on the system type (macOS or other systems
# ).
# Modify the author and commit date of the identified commit using the git 
# filter-branch command.
# Note that modifying the commit date of a Git record can cause confusion in 
# the Git history, so please make sure to back up your repository before 
# performing this operation and consult with other developers if necessary.
#
# e.g.
#     When you execute this script, the submit date of a commit with message
#     `feat(08/16): add script for change commit date ` will change to `08/16`

#!/bin/bash

# Find the SHA of the latest n commits that contain a date
n=${1:-1}
shas=$(git log --grep='([0-9]\{2\}/[0-9]\{2\})' --pretty=format:%H -$n)

# Loop over each commit to extract the date from the commit message
for sha in $shas; do
  commit_date=$(git log --format=%B -n 1 $sha | grep -o '([0-9]\{2\}/[0-9]\{2\})' | tr -d '()')
  if [[ -n $commit_date ]]; then

    # Format the date string to a format that Git can accept
    if [[ "$(uname)" == "Darwin" ]]; then
      # On macOS, use the following format to convert the date string
      year=$(date +%Y)
      hour=$(date +%H)
      minute=$(date +%M)
      second=$(date +%S)
      git_date=$(LC_TIME=en_US.UTF-8 date -j -f "%m/%d/%Y %H:%M:%S" "$commit_date/$year $hour:$minute:$second" +"%a %b %d %H:%M:%S %Y %z")
    else
      # On other systems, use the following format to convert the date string
      git_date=$(date -d "$commit_date $(date +%Y)" +"%a %b %d %H:%M:%S %Y %z")
    fi

    # Modify the commit date
    FILTER_BRANCH_SQUELCH_WARNING=1 git filter-branch -f --env-filter \
      "if [ \$GIT_COMMIT = $sha ]
       then
           export GIT_AUTHOR_DATE='$git_date'
           export GIT_COMMITTER_DATE='$git_date'
       fi"
  else
    echo "No commit message containing date found in $sha."
  fi
done