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[RESOLVED] Help please: CRON works on one Omega2+ but not the other.

  • I have two Omega2+ one of which is mounted on the Power Dock and the other is mounted on the Expansion Dock

    The cron on the Omega2+ on the Expansion works. I've written a small shell script to make the Omega LED go into heartbeat mode and then return to default-on. I scheduled it to run every minute.

    When I place the same program on the Omega2+ on the Power Dock and create the exact same crontab entry pointing to the same shell script (same directory structure as the other Omega2+), the cron does not run the script. Very strange.
    The steps were:

    • Create the shell script
    • set it to executable
    • create the cron entry via crontab -e
    • restart the cron /etc/init.d/cron restart

    If I manually run the script, it works just fine.

    Any idea what could be the issue or the best remedy to get this sucker working?

    • Update 1
      Reloaded the latest version omega2p-v0.1.9-b155.bin
      No change.
      Removed the OLED board just in case.
      No change.

    • Update 2
      It would appear that the cron is trying to do something.
      The cron entry looks like this
      */1 * * * * /root/my.sh > /tmp/output1.txt 2>$1
      It is creating the output1.txt file but nothing is being written to it as is the case on the other Omega2+ which means that the script /root/my.sh is not being run. Why?

    This is where I'm at a loss. I've no idea how the scheduler invokes the script. I'm now of the view that something is corrupted in the OS. I've performed a factory reset and gone through the process of initialising the Omega as if it was brand new out of the box but that has not solved the issue unless I missed something in the installation sequence.

  • This post is deleted!

  • Update 3

    The script I am using in the cron entry for the Omega2+ on the Power Dock:

    # !/bin/ash -e
    # Filename: my1.sh
    # Description: Controls the Omega2+ LED
    # Rapidly pulses the LED
    echo timer > /sys/class/leds/omega2p\:amber\:system/trigger
    echo 75 > /sys/class/leds/omega2p\:amber\:system/delay_on
    echo 75 > /sys/class/leds/omega2p\:amber\:system/delay_off
    sleep 4
    echo default-on > /sys/class/leds/omega2p\:amber\:system/trigger
    cat /sys/class/leds/omega2p\:amber\:system/trigger

    Turns the LED on to rapid pulse for 4 seconds, then resets the LED to ON then displays the trigger status and date, then exits.

    The cron entry to invoke the script every minute.

    root@Omega-6049:~# crontab -l
    #*/1 * * * * /root/squote.sh >> /tmp/output.txt 2>$1
    */1	*	*	*	*	/root/my1.sh > /tmp/output1.txt 2>$1
    # last line must be a comment

    [Edit] as @György-Farkas posted below the error is in the crontab entry. I mistakenly entered a $ instead of an &. The 2>&1 is an indicator to the shell script that you want to include the error messages into the output of your command.

    root@Omega-6049:~# crontab -l
    #*/1	*	*	*	*	/root/squote.sh >> /tmp/output.txt 2>&1
    */1	*	*	*	*	/root/my1.sh > /tmp/output1.txt 2>&1
    # last line must be a comment

    snapshot of ps to show the cron is operational

    root@Omega-6049:~# ps | grep cron
     9098 root      1188 S    /usr/sbin/crond -f -c /etc/crontabs -l 8
    12240 root      1184 S    grep cron

    At the moment (or a second after) the cron should invoke the script there should be an entry in the process list to show that it is running.

    root@Omega-6049:~# ps | grep sh
     1845 nobody    1292 S    /usr/sbin/shellinaboxd -t --service=/:LOGIN --css /usr/lib/shellinabox/style.css
     1857 nobody    1292 S    /usr/sbin/shellinaboxd -t --service=/:LOGIN --css /usr/lib/shellinabox/style.css
     8505 root      1192 S    -ash
    11322 root       896 S    /sbin/askfirst /usr/libexec/login.sh
    12342 root         0 Z    [sh]
    12345 root      1184 S    grep sh

    As you can see there is no line matching that would indicate that my1.sh is running except that process number 12342 is suspect.

    On my other Omega2+ (which is working as expected on the Expansion Dock) the script I am running on the minute is as follows:

    #!/bin/ash -e
    # Filename: my.sh
    # Description: Controls the Omega2+ LED
    echo timer > /sys/class/leds/omega2p\:amber\:system/trigger
    echo 75 > /sys/class/leds/omega2p\:amber\:system/delay_on
    echo 75 > /sys/class/leds/omega2p\:amber\:system/delay_off
    sleep 4
    echo default-on > /sys/class/leds/omega2p\:amber\:system/trigger
    cat /sys/class/leds/omega2p\:amber\:system/trigger

    The cron entry (the second one).

    root@Omega-B779:~# crontab -l
    */1	*	*	*	*	/root/rgb-control.sh > /tmp/output.txt 2>&1
    */1	*	*	*	*	/root/my.sh > /tmp/output1.txt 2>&1
    # last line must be a comment

    snapshot of the ps just after the minute mark

    root@Omega-B779:~# ps | grep sh
      453 root       896 S    /sbin/askfirst /usr/libexec/login.sh
     2430 nobody    1292 S    /usr/sbin/shellinaboxd -t --service=/:LOGIN --css /usr/lib/shellinabox/style.css
     2439 nobody    1292 S    /usr/sbin/shellinaboxd -t --service=/:LOGIN --css /usr/lib/shellinabox/style.css
    13521 root      1184 S    /bin/sh -c /root/rgb-control.sh > /tmp/output.txt 2>&1
    13522 root      1184 S    /bin/sh -c /root/my.sh > /tmp/output1.txt 2>&1
    13523 root      1184 S    {my.sh} /bin/ash -e /root/my.sh
    13524 root      1184 S    {rgb-control.sh} /bin/ash /root/rgb-control.sh
    13527 root      1184 S    {rgb-led.sh} /bin/sh -e /root/rgb-led.sh
    13774 root      1184 S    grep sh
    18469 root      1184 S    -ash

    Process number 13523 is in progress so on this Omega2+ everything is working nicely.

    The contents of the output1.txt file to show that the process ran as expected.

    root@Omega-B779:/tmp# cat output1.txt
    none timer [default-on] netdev transient mmc0 gpio heartbeat morse oneshot 
    Sun Feb 12 12:39:04 AWST 2017

    If I swap the suspect Omega2+ from the Power Dock to this one (Expansion Dock), the issue with the cron still exists so it is not Dock related.

    Any ideas?

  • @Chris-Parker

    There are two typos in the first cron entry, there is $ instead of &

    /root/squote.sh >> /tmp/output.txt 2>$1
    /root/my1.sh > /tmp/output1.txt 2>$1

    /root/squote.sh >> /tmp/output.txt 2>&1
    /root/my1.sh > /tmp/output1.txt 2>&1

    logread | tail can show you that cron runs and allows to run your script.

    Good luck!

  • @György-Farkas well spotted.

  • @György-Farkas

    Thank you.

    So damned simple I couldn't see it.

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