Difference between revisions of "Cron"
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| − | The software utility cron automates system maintenance or administration by scheduling jobs (commands or shell scripts) to run periodically at fixed times, dates, or intervals. From the Greek word for time, χρόνος chronos. See | + | The software utility cron automates system maintenance or administration by scheduling jobs (commands or shell scripts) to run periodically at fixed times, dates, or intervals. From the Greek word for time, χρόνος chronos. See http://en.wikipedia.org/wiki/Cron or read the man pages: |
man crond | man crond | ||
Revision as of 18:44, 22 December 2013
The software utility cron automates system maintenance or administration by scheduling jobs (commands or shell scripts) to run periodically at fixed times, dates, or intervals. From the Greek word for time, χρόνος chronos. See http://en.wikipedia.org/wiki/Cron or read the man pages:
man crond
crond is a background daemon that parses individual crontab files and executes commands on behalf of the users in question.
man crontab
crontab -l [-u user] - list crontab for user
crontab -e [-u user] - edit crontab for user
Listed below is a typical crontab file that reads the sensors, generate system status page and graphs, and records a sample of video:
# # email me computer status at 6 pm 0 18 * * * /home/hivetool/ssmtp_test3 1> /dev/null # # email me hive status every 24 hours (6 am) 0 6 * * * /home/hivetool/send_email.pl 1> /dev/null # # Check hive instruments every 5 minutes 0,5,10,15,20,25,30,35,40,45,50,55 * * * * /home/hivetool/hive.sh # # Check the server status 0,5,10,15,20,25,30,35,40,45,50,55 * * * * /home/hivetool/server_status.sh > /var/www/htdocs/server_status.txt # # grab a frame and record it as a jpg 4,9,14,19,24,29,34,39,44,49,54,59 * * * * /bin/timeout 60 /home/hivetool/grab_frame.sh 2> /home/hivetool/grab_frame.cron # # generate daily graph for hive at midnight 0 0 * * * /var/www/htdocs/graph_hive_variable.pl -m -o /var/www/htdocs/daily_filtered -h 300 0 0 * * * /var/www/htdocs/graph_hive_variable.pl -mr -o /var/www/htdocs/daily_raw -h 300 # # generate wide graph with all the data at 5 minutes before midnight 55 23 * * * /var/www/htdocs/graph_hive_variable.pl -o /var/www/htdocs/all_filtered 55 23 * * * /var/www/htdocs/graph_hive_variable.pl -r -o /var/www/htdocs/all_raw # # record 60 seconds of audio stream at 4 am, 10 am, 4 pm and 10 pm #0 4,10,16,22 * * * streamripper localhost:8000/hive1.ogg -l 60 -s -a /var/www/htdocs/audio/hive1_%D # # record 60 seconds of audio stream at 10:05 10:10 10:15 etc #5,10,15,20,25,30,35,40,45,50,55 10 * * * streamripper localhost:8000/hive1.ogg -l 60 -s -a /var/www/htdocs/audio/hive1_%D # # record 30 seconds of video every 30 minutes 0,30 7,8,9,10,11,12,13,14,15,16,17 * * * /bin/timeout 60 /home/paul/rh 1> /home/paul/rh.cron #
