Avi Mehenwal

# Configuration Files

linuxconfigurationfilesrccroncrontab
Why are configuration files named as rc files in linux?
Run commands
How to run a script on linux startup? Generic solution for linux?
Use crontab #crontab -e; @reboot sh $HOME/test.sh or Add your script to /etc/init.d/ directory, Update your rc run-levels: $ update-rc.d myScript.sh defaults NN where NN is the order in which it should be executed. 99 for example will mean it would be run after 98 and before 100.

# Cronjobs

  • Leave an empty line at the end of the file, else cron ignores the file
  • How to check cronjobs logs? grep CRON /var/log/syslog
  • How do I version control them?
  • crontabk file location?
    • /tmp/crontab.RCHxxs/crontab
    • get path of current opened file
    • :!realpath %
  • Replace your crontab with custom crontab
  • How to log application logs to syslogs
    • logger "have more fun" > /var/log/mycustomlog
  • How to log timestamp with log messages?
  • How to check if a package is already installed, else install it?
  • Is it possible to import bash functions from shared files? 
# create and install new crontab
crontab /home/username/filename
crontab -u (whoami) $HOME/aviscripts/avi_crontab

@reboot   cd /home/me/  && sh myscript.sh

grep CRON /var/log/syslog
journalctl -u cron.service
journalctl -t CROND

logger "have more fun" > /var/log/mycustomlog

journalctl -u cron.service | grep -A9 -B5 HOME/aviscripts/on_startup_script.sh

May 27 13:09:07 mehenwal CRON[694]: pam_unix(cron:session): session opened for user avi by (uid=0)
May 27 13:09:07 mehenwal CRON[731]: (avi) CMD (bash $HOME/aviscripts/on_startup_script.sh)
May 27 13:09:07 mehenwal CRON[694]: (CRON) info (No MTA installed, discarding output)
May 27 13:09:07 mehenwal CRON[694]: pam_unix(cron:session): session closed for user avi
    • or
  • Buy me a coffeeBuy me a coffee

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