When you want to backup your files on computers every day/week/month, you can use backup software. In addition to those, I do the way to rely on Github when save arbitrary files. For example, a config file for some app, a daily memo markdown file or setting.json of VScode etc.

In this post, I would share an idea to backup any specific files to your github repository. The point is that you can back up even one file for any folders.

Steps

• Create a Github repository and local repository.

• Specify files to backup.

• Cron triggers the shell script.

• The shell script checks if the files are updated. If so, copy overwrite them to the local repository.

• Push to github repository.

Prerequisites

We need these or alternatives:

• unix, shell, cron

• Github account

Create Local and Remote repository

Create a repository and setup to connect with CLI.

Important Note: the repository should be private.

Creating a personal access token (with permission “repo: Full control of private repositories”) would be secure. Put the token in you .env file.

MY_TOKEN=<personal access token>

Create shell script

Create a shell script file, with a name cron_git_arbitray_file.sh for example. Put it in the same directory as .env.

Paste the script below.

Parameters to set are like this. List is a list of files to be backed up. REMOTE_REPO is github repository, LOCAL_REPO is where local repository. SUBDIR_REPO is optional to use subdirectory under REMOTE_REPO. Set USERNAME and PASSWORD for github name and token.

#!/bin/bash

# Back up specific files on any directories.
# Using cron job, check update for each file.
# Up-to-date files are copied to local repository
# and pushed to github.
#
# Usage: 
#   $ bash ./cron_git_arbitray_file.sh
# cron example. execute at every 4am: 
#   0 4 * * * (cd /home/dir/of/sh/ && bash cron_git_arbitrary_file.sh)
# Log: ./log/yyyymmdd.log is saved.

#
# Parameters
# ----------
# declare -a List=(
#   "/home/user/full/path/to/file.file"
#   "/home/user/.config/path/to/file.file"
# )
# REMOTE_REPO="github.com/username/reponame.git"
# LOCAL_REPO="/home/user/local/reponame/"
# SUBDIR_REPO="sub-dir-in-repo/" # optional
# USERNAME="github-username"
# PASSWORD="password-token"
# ----------

# Set files to auto backup
declare -a List=(
  "/home/user/full/path/to/file.file"
  "/home/user/.config/path/to/file.file"
)

source ./.env
REMOTE_REPO="github.com/username/reponame.git"
LOCAL_REPO="/home/user/local/reponame/"
SUBDIR_REPO="sub-dir-in-repo/" # optional
USERNAME="github-username"
PASSWORD=$MY_TOKEN

# <dir_of_sh>/log/YYYYMMDD.log is created.
PWD=$(pwd)
log_file=$PWD"/log/$(date +%Y%m%d).log"
mkdir -p $PWD"/log" && touch $log_file

# confirm SUBDIR_REPO exists
mkdir -p $LOCAL_REPO$SUBDIR_REPO

# main
echo "----- $(date +%Y/%m/%d-%H:%M:%S): $(basename "$0") -----" >>$log_file
cd $LOCAL_REPO
update_cnt=0

# check update for each item
for item in "${List[@]}"; do

  # full/path/file to full_path_file
  filename_full=$SUBDIR_REPO"${item//\//_}"

  file1=$item
  file2=$LOCAL_REPO$filename_full
  echo "Update check: "$file1 >>$log_file

  command1="date +%Y%m%d%H%M%S -r "$file1
  command2="date +%Y%m%d%H%M%S -r "$file2

  a=$(eval $command1)
  b=$(eval $command2)

  if [[ $a -eq $b ]]; then

    echo "  No update." >>$log_file

  else

    echo "  Found update. Copy it to local repo. Git add, commit, push." >>$log_file

    ((update_cnt = update_cnt + 1))

    cp -p $file1 $file2

    $(eval "git add "$file2)

  fi
done

if [[ $update_cnt -gt 0 ]]; then
  git commit -m "Automatic back up"
  git push -u https://$USERNAME:$PASSWORD@$REMOTE_REPO master >/dev/null 2>&1
fi

Logging In the script above, log files are created in log/ with a name like :

----- 2023/07/28-07:18:08: cron_git_arbitrary_file.sh -----
Update check: /home/user/.config/Code/User/settings.json
No update.
Update check: /home/user/Desktop/backup/cron_git_arbitrary_file.sh
Found update. Copy it to local repo. Git add, commit, push.

This is just redirecting echo "XXXX" >>$log_file . Create cron Write in your crontab like this.

0 4 * * * (cd /home/dir/of/sh/ && bash cron_git_arbitrary_file.sh)

cd /home/dir/of/sh/ is for changing directory for logging.

I have shown how to push specific files to the Github repository to backup. The script can run automatically using cron.

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