cronjob run every 5 seconds

sag2662 · 04-11-2023, 06:13 AM

Quote:

Originally Posted by pan64

does this machine run continuously?

yes it is

sag2662 · 04-11-2023, 06:15 AM

Quote:

Originally Posted by michaelk

Without knowing what command actually does it is not possible to know whats wrong. How long does it take to actually run the it once? If it takes more then a minute to run the command 12 times you will have multiple processes which continue into the next day. You are also missing the sleep 5 command in your loop.

I am just running ping -c hostname

michaelk · 04-11-2023, 07:44 AM

What is the count value for -c?

pan64 · 04-11-2023, 08:01 AM

probably you can find something in the log of cron
additionally you may try to create your own log about the executions.

sag2662 · 04-11-2023, 08:56 AM

Quote:

Originally Posted by michaelk

What is the count value for -c?

ping -c 1 hostname

sag2662 · 05-15-2023, 02:22 AM

Quote:

Originally Posted by pan64

does this machine run continuously?

yes is it possible to schedule cronjob for every second

michaelk · 05-15-2023, 05:09 AM

Code:

/etc/systemd/system/mytimer.service:
[Unit]
Description=my timer service
[Service]
User=my_name
ExecStart=/home/username/script.sh

/etc/systemd/system/mytimer.timer:
[Unit]
Description=my_timer timer

[Timer]
OnUnitActiveSec=5s
OnBootSec=5s

[Install]
WantedBy=timers.target

chrism01 · 05-15-2023, 11:43 PM

Quote:

is it possible to schedule cronjob for every second

answer : No - see my prev post #10

sag2662 · 05-16-2023, 01:54 AM

Quote:

Originally Posted by chrism01

answer : No - see my prev post #10

nohup is creating bulk requests and I dont want to use it. My goal is to run continous ping checks between two hosts, so if any packetloss is there it should be reported in the logs.

Code:

for ((i=0; i<12; i++))
do
ping -c 10 $host | grep "packet loss" 
sleep 1
done


cronjob * * * * * sh /home/ping.sh

this runs every 5 or 6 seconds seconds, how to run it for each second ?

pan64 · 05-16-2023, 01:59 AM

man sleep?

MadeInGermany · 05-16-2023, 03:05 AM

Quote:

Originally Posted by sag2662

nohup is creating bulk requests and I dont want to use it. My goal is to run continous ping checks between two hosts, so if any packetloss is there it should be reported in the logs.

Code:

for ((i=0; i<12; i++))
do
ping -c 10 $host | grep "packet loss" 
sleep 1
done


cronjob * * * * * sh /home/ping.sh

so this mean now the ping checks will be every second.

You do not need a loop or sleep.
The following does everything with one ping:

Code:

#!/bin/sh
host="localhost"
ping -n -i 2 -c 29 -w 60 $host >/dev/null || echo "alert: $host did not respond"

-n no hostname lookups
-i 2 every 2 seconds
-c 29 ping samples
-w 60 seconds total timeout

Or set a 1 second per-ping timeout:

Code:

ping -n -i 2 -c 29 -W 1 $host >/dev/null || echo "alert: $host did not respond"

murugesandins · 05-01-2024, 10:14 AM

Due to your query I have installed cron at windows using CYGWIN_NT and started cron service.
1. Create a shell script file
Example:

Code:

$ cat /home/murugesandins/mycron.sh
#!/bin/bash
/usr/bin/date "+%a %d-%b-%Y %I:%M:%S %p %Z" >> /tmp/output.txt
$ chmod +x /home/murugesandins/mycron.sh

Create cron job

Code:

$ crontab -e

Add following lines:

Code:

#There is no option to mention seconds. Hence use sleep... to execute at related timings
#Minute Hour DayOfMonth MonthOfYear DayOfWeek Create six cron job to execute at each 10 seconds.
      *    *          *           *         * ( /usr/bin/sleep 10;/home/murugesandins/mycron.sh )
      *    *          *           *         * ( /usr/bin/sleep 20;/home/murugesandins/mycron.sh )
      *    *          *           *         * ( /usr/bin/sleep 30;/home/murugesandins/mycron.sh )
      *    *          *           *         * ( /usr/bin/sleep 40;/home/murugesandins/mycron.sh )
      *    *          *           *         * ( /usr/bin/sleep 50;/home/murugesandins/mycron.sh )
      *    *          *           *         * ( /usr/bin/sleep 60;/home/murugesandins/mycron.sh )

Save and quit
Each 10/20/30/40/50/60 seconds the output written at /tmp/output.txt
Example:

Code:

$ cat /tmp/output.txt
Wed 01-May-2024 08:38:11 PM IST
Wed 01-May-2024 08:38:21 PM IST
Wed 01-May-2024 08:38:31 PM IST
Wed 01-May-2024 08:38:41 PM IST
Wed 01-May-2024 08:38:51 PM IST
Wed 01-May-2024 08:39:01 PM IST
Wed 01-May-2024 08:39:11 PM IST
Wed 01-May-2024 08:39:21 PM IST
Wed 01-May-2024 08:39:31 PM IST
Wed 01-May-2024 08:39:41 PM IST
Wed 01-May-2024 08:39:51 PM IST
Wed 01-May-2024 08:40:01 PM IST
Wed 01-May-2024 08:40:12 PM IST
Wed 01-May-2024 08:40:22 PM IST
Wed 01-May-2024 08:40:32 PM IST
Wed 01-May-2024 08:40:42 PM IST
Wed 01-May-2024 08:40:52 PM IST
Wed 01-May-2024 08:41:02 PM IST
Wed 01-May-2024 08:41:11 PM IST
Wed 01-May-2024 08:41:21 PM IST
Wed 01-May-2024 08:41:31 PM IST

Code:

$ crontab -l
# DO NOT EDIT THIS FILE - edit the master and reinstall.
# (/tmp/crontab.1ohnI6c1ek installed on Wed May  1 20:32:21 2024)
# (Cron version V5.0 -- $Id: crontab.c,v 1.12 2004/01/23 18:56:42 vixie Exp $)
#Minute Hour DayOfMonth MonthOfYear DayOfWeek Create six cron job to execute at each 10 seconds.
      *    *          *           *         * ( /usr/bin/sleep 10;/home/murugesandins/mycron.sh )
      *    *          *           *         * ( /usr/bin/sleep 20;/home/murugesandins/mycron.sh )
      *    *          *           *         * ( /usr/bin/sleep 30;/home/murugesandins/mycron.sh )
      *    *          *           *         * ( /usr/bin/sleep 40;/home/murugesandins/mycron.sh )
      *    *          *           *         * ( /usr/bin/sleep 50;/home/murugesandins/mycron.sh )
      *    *          *           *         * ( /usr/bin/sleep 60;/home/murugesandins/mycron.sh )
$ crontab -r
$ crontab -l
no crontab for murugesandins