Need run a shell script once a day at random time. (so once every day between 00:00-23:59).
I know the sleep command, and the cron too, but
cron has not random timessleep solution - not very nice - my idea is launch the script every midnight and sleep random time at the start of the script.Is here something more elegant?
If you have the at command, you can combinte the cron and the at.
Run from a cron every midnight the next script:
#!/bin/bash
script="/tmp/script.sh" #insert the path to your script here
min=$(( 24 * 60 ))
rmin=$(( $RANDOM % $min ))
at -f "$script" now+${rmin}min
The above will run the at command every midnight and will execute your script at random time . You should check your crontab how often is the atrun command started. (The atrun runs the commands stored with the at)
The main benefit in comparison with the sleep method: this "survives" the system reboot.
I would simply launch you script at midnight, and sleep for a random time between 0 and 86400 seconds. Since my bash's $RANDOM returns a number between 0 and 32767:
sleep $(( ($RANDOM % 1440)*60 + ($RANDOM % 60) ))
The best alternative to cron is probably at
at man pageUsually, at reads commands from standard input, but you can give a file of jobs with -f.
Time wise, you can specify many formats. Maybe in your case the most convenient would be
at -f jobs now + xxx minuteswhere your scripts gives xxx as a random value from 1 to 1440 (1440 minutes in a day), and jobs contains the commands you want to be executed.
You can use cron to launch bash script, which generates pseudorandom timestamp and gives it to unix program at
I see you are familiar with bash and cron enough, so at will be a piece of cake for you. Documentation as always "man at" or you can try wiki
Nothing prevents you from running sed to patch your crontab as the last thing your program does and just changing the next start time. I wouldn't sleep well though.
