Linux UpSkill Challenge Day 10 - Scheduling tasks

Source

• https://linuxupskillchallenge.org/10/
• https://www.youtube-nocookie.com/embed/ktjabe8enxU

bash arrays

• Intro to bash arrays

myarray(1 2 3)
mytextarray("text1" "text2")

crontab

• special cron strings: @reboot, @yearly/annually, @monthly, @weekly, @daily, @midnight, @hourly

sudo crontab -u root -e
# every day at 4am create compressed backup of home directory
0 4 * * * tar -cvzf /var/backups/home.$(date -I).tar.gz /home/
# every day at 4:30am remove all home dir backups older than 3 days
30 4 * * * find /var/backups -name "home.*.tar.gz" -mtime +3 -delete

Script to update docker containers

 #!/bin/bash
 dockerdir="/home/p10/docker"                 
 for dir in $(ls $dockerdir); do
   cd "$dockerdir/$dir"
   docker compose pull && docker compose up -d
 done

# every Sunday at 12am run dockerpull script
0 0 * * 7 /home/p10/.local/bin/dockerpull

journalctl

# list logs for a specific systemd unit
journalctl -u [unit]
 
# list logs since a particular time
journalctl --since "[time]"

at

# schedule a one-off command
at
 
# list pending at jobs
atq
 
# remove a pending at job
atrm

EOF