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I was trying to use my pi and a bluetooth speaker as an alarm clock.

I've setup a cronjob by doing

sudo crontab -e

in the crontab file, I added 

40 8 * * 1-5 /home/XXXXX/alarm.sh &> alarm.log

the alarm.sh script is as following:

#!/bin/bash
sudo hciconfig hci0 up
bluez-test-audio connect MAC_OF_SPEAKER
bluez-test-device trusted MAC_OF_SPEAKER yes
mplayer -ao alsa:device=clock MY_MUSIC.m4a

The problem now is that the cronjob won't work. If I run the script manually, the speaker plays the .m4a file correctly. But cronjob won't execute at 08:40 in the morning.

Please give me some advice.

Thanks

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2 Answers 2

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OK, as @joan mentioned in the comment, I need to "provide full path to files in cron jobs."

Cron jobs were executed, but since I didn't provide full path to alarm.log, it is not in my user home directory.

So what I did to fix the problem:

1.change cronjob to 

40 8 * * 1-5 /home/XXXXX/alarm.sh > /home/XXXXX/alarm.log 2>&1

redirect output was not necessary, but it helped me to find out where went wrong.

2.change the alarm.sh script to 

#!/bin/bash
sudo hciconfig hci0 up
bluez-test-audio connect MAC_OF_SPEAKER
bluez-test-device trusted MAC_OF_SPEAKER yes
mplayer -ao alsa:device=clock FULL_PATH_TO_MY_MUSIC/MY_MUSIC.m4a //full path is needed
bluez-test-audio disconnect MAC_OF_SPEAKER

The music played as scheduled.

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Try restarting the cron service with

sudo service cron restart

after editing your cronjob.

If this doesn't help, try using a simple echo bash script as a cronjob.

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  • No, it doesn't work. The echo script was not executed...
    – Eniaczz
    Commented Jun 25, 2015 at 1:14
  • Try: 40 8 * * 1-5 /bin/bash /home/XXXXX/alarm.sh &> alarm.log
    – scherzkrapferl
    Commented Jun 25, 2015 at 1:40
  • OK, I added */1 * * * * ~/echo_hello.sh > echo.log, the file echo.log was created and has "hello" in it. But if I just register ~/echo_hello.sh, nothing gets printed on the screen.
    – Eniaczz
    Commented Jun 25, 2015 at 1:51
  • I checked my own cronjobs and found out that I always specified "/bin/bash" like mentioned above. Another possibility that could help is using "crontab -e" instead of "sudo crontab -e".
    – scherzkrapferl
    Commented Jun 25, 2015 at 1:56
  • 1
    @Eniaczz You should always give full paths to files in cron jobs. For instance mplayer -ao alsa:device=clock MY_MUSIC.m4a assumes that MY_MUSIC.m4a is in the current directory. I have no idea what the default current directory is for a cron job, it's not the directory containing MY_MUSIC.m4a though.
    – joan
    Commented Jun 25, 2015 at 6:15

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