Script to update jenkins.war to latest when using Jenkins docker

update-jenkins-version-docker.sh

#! /bin/sh

backup_folder="./backup"
jenkins_war="./jenkins.war"
backup_name="jenkins.war.$(date +"%Y_%m_%d_%H_%M_%S")"

mkdir -p $backup_folder

if [ "$(ls -A $backup_folder)" ]; then
    latest_backup=$(ls -t1 $backup_folder | head -n 1)
    latest_backup_sha1sum=$(sha1sum $backup_folder/$latest_backup | awk '{print $1;}')
    current_sha1sum=$(sha1sum $jenkins_war | awk '{print $1;}')
    echo "$latest_backup_sha1sum"
    echo "$current_sha1sum"
    if [ "$latest_backup_sha1sum" = "$current_sha1sum" ]; then
        echo "File is identical to latest backup, skipping backup"
        backup_name=$latest_backup
    else
        echo "New backup. Backing up to '$backup_folder/$backup_name'"   
        mv $jenkins_war $backup_folder/$backup_name
    fi
else
    current_sha1sum=$(sha1sum $jenkins_war | awk '{print $1;}')
    echo "No backups yet. Backing up to '$backup_folder/$backup_name'"   
    mv $jenkins_war $backup_folder/$backup_name
fi

wget http://updates.jenkins-ci.org/latest/jenkins.war -O $jenkins_war
new_sha1sum=$(sha1sum $jenkins_war | awk '{print $1;}')

if [ "$current_sha1sum" = "$new_sha1sum" ]; then
    echo "Files are the same, deleting backup"
    rm $backup_folder/$backup_name
fi

chown jenkins:jenkins $jenkins_war