at
Used to schedule a task once
at now + 3 minutes

Cron Jobs
Managed by the cron daemon

• cron daemon checks the crontab file every minute
  • executes any tasks waiting to execute
    Format:
    Minute, Hour, Day, Month, Day of Week

Run echo "Hello" at 0900 on 30APRIL

crontab 00 09 30 04 0 /bin/echo "Hello"
crontab -e = Edit
crontab -l = List

cron.allow or cron.deny

GIT
git clone <repo> = Get local copy of a repo
git pull <repo> = Update repo
git merge <repo> = Merge changes to a master branch
git commit <repo> = Submit code to be merged into the master repo. Creates a "snapshot" of repo.
git push <files> <remote repo> = Upload a local working copy to a remote repo
git config <repo> = Set options for a repo, users, or global
git init <repo? = Create or reinitialize a repo
git add <repo> = Add files to be tracked by repo

Orchestration

Infrastructure Automation

• Accomplishes large-scale deployments

Build Automation

• Emphasizes initial OS deployment
• Kickstart files

Infrastructure as Code

• Configuring infrastructure and applications with a single configuration file

Tools
Ansible - Agentless, uses YAML, and playbooks to define configs.
Puppet - Uses agents on target systems.
Chef - Cookbooks deliver configs; used in clouds and on-premises.
Kubernetes - Container deployment/app automation
OpenStack - Used as an IaaS to manage cloud resources.