Sleep command to run after exactly every one hour

Question

I need your small help, i have one script which i can not schedule on crontab. But I am using sleep command.

I am facing issue while using sleep command.

My script took 10 or 15 min to complete ( run time) and I use sleep(3600) which means it sleep for another one hour

But my requirement is that my script start at 9:00, 10:00... and so on . Due to my script execution time which i am taking right now 10 min ( it vary), and after that sleep(3600) command ,my script next run start at 10:10 instead of 10:00

Can anyone help me how i can correct it this so that script run at exactly every hour.

Why can't you use the cron which is designed exactly for that? — Julie Pelletier, Feb 14 '17 at 06:43
i don't have permission and due to some restriction i can not use crotab — Pallvi Mahajan Sapen, Feb 14 '17 at 06:49
Have a look here for details of how to disown a process: http://stackoverflow.com/questions/20338162/how-can-i-launch-a-new-process-that-is-not-a-child-of-the-original-process — u628898, Feb 14 '17 at 06:53

score 2 · Answer 1 · answered Feb 14 '17 at 06:57

2

#!/bin/bash

function MY_CODE(){
    START_TIME_SECONDS=$(date +%s)
    <your code>
    END_TIME_SECONDS=$(date +%s)
    SCRIPT_RUN_TIME_IN_SECONDS=$((${END_TIME_SECONDS}-${START_TIME_SECONDS}))
    SLEEP_TIME=$((3600-${SCRIPT_RUN_TIME_IN_SECONDS}))
    sleep ${SLEEP_TIME}
}

MY_CODE()

answered Feb 14 '17 at 06:57

Kamaraj

4,365

1

Why use all uppercase for normal variables? – codeforester Feb 14 '17 at 07:12
1

@codeforester That is the convention in shell scripts. It makes variables easier to distinguish from commands (which are usually lowercase). – JigglyNaga Feb 14 '17 at 09:42
@JigglyNaga No, the convention is to use upper-case for environment variables, i.e. exported shell variables. Using uppercase like this makes it hard to read. – Kusalananda Feb 14 '17 at 10:42
@Kusalananda. There is no universally agreed upper/lower case convention on shell script variable names other then for certain environment values which are documented in various standards and specifications. – fpmurphy Feb 14 '17 at 12:06
@fpmurphy1 Related: http://unix.stackexchange.com/questions/42847/are-there-naming-conventions-for-variables-in-shell-scripts – Kusalananda Feb 14 '17 at 12:11
@Kusalananda. Yes, lots of different organizations have produced coding and style guides for Bash and lots more. That is because there is no one agreed convention. – fpmurphy Feb 16 '17 at 10:29

pixelou · Answer 2 · 2017-02-14T10:51:56.840

Since your objective is to schedule execution based on start time, you can schedule each script execution like this:

#!bin/bash

function runattime {
    execution_time=$1
    delay=$(( $(date -d "$1" "+%s") - $(date "+%s") ))
    if [ $delay -le 0 ]; then
        echo "negative delay, probably due to incorrect date argument"
    else
        sleep $delay && ${@:2}
    fi
}


# One shot run
runattime 11:50 echo blah & 
runattime 11:51 echo bleh & 


# Everyday run
while true; do
    runattime 11:50 echo hola & 
    runattime 11:51 echo hello & 
    sleep 86400  # wait for next day and loop
done

To have the script run in the background even when you are disconnected you can use the nohup command from bash.

Sleep command to run after exactly every one hour

2 Answers2