Example of cron base auto release script using a git remote origin with lock file in case of long release process

update_git_and_release.sh

#!/bin/bash

# Example of cron base auto release script using a git remote origin with lock file in case of long release process
# * * * * * /path/to/the/file/update_git_and_release.sh

# die on non-zero status
set -e;
# die on undefined variable
set -u;


# Find current directory of the script
DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"

# CD to the script directory
cd "$DIR"

LOCK_FILE="/tmp/release.lock"



if [ ! -f $LOCK_FILE ]; then
    touch $LOCK_FILE;
    chmod 777 $LOCK_FILE;
fi

#The call “exec 200>$LOCK_FILE” will open the file named in $lock for reading, and assign it file handle 200
exec 8>$LOCK_FILE;

#Tells flock to exclusively lock the file referenced by file handle 200 or exit with code 1
if flock -n 8 ;then
        # Update the current branch from remote
        git fetch
        
        # Check if the current branch is behind the origin
        # git status -bz will display "## master...origin/master [behind 15]" for example
        # grep -aq is silently looking for the behind string (will the tracked branch name contains behind)
        # grep exit is sent to the $BEHIND variable
        git status -bz | grep -aq "behind" && BEHIND=1 || BEHIND=0
        
        if [ $BEHIND -eq 1 ]
        then
                # force pull new code in the directory quietly
                git pull -qf
                # Execute release script after the pull
                ./release_script.sh
        fi
fi