[SOLVED] crontab does not reread the crontab file upon modification of the latter.

stf92 · 08-01-2015, 12:48 PM

Hi: I created, as root, a file with 'crontab -e', whose contents is:

Code:

* * * * * /almacen/work/batt_low/bl02.sh

where bl02.sh is

Code:

bill@server:/almacen/work/batt_low$ cat bl02.sh
#!/bin/bash
 
## FILE NAME: bl.sh
## PROG APPL: query the battery charge level. Audibly alert users
## when level is bellow THRESHOLD.

## Instructions: in a root console, do 'crontab -e', which will open
## /var/spool/cron/crontabs/root, ready to edit. In the bottom line
## you will read some fancy file name. It does not matter. The
## file you are editing is that mentioned above. Type 
## '* * * * * <this script complete file name>', without the quotes.
## Close the file. Now the script will be run every minute.

THRESHOLD=1200
a1=$(grep remaining /proc/acpi/battery/BAT0/state) 
current_level=$(echo $a1 | grep -o '[0-9]\+') 
if [ $current_level -gt THRESHOLD ]
then 
	exit 0		#Battery level OK
	fi

	## Battery is low here
	# notify-send "****** Battery low *******" "*********************"

	## We assume we are running as root (alsactl).
	alsactl store           

	## The following commands taken from man amixer, EXAMPLES.
	amixer -c 0 sset Master playback 100 unmute
	amixer -c 0 sset PCM 100 
	amixer -c 0 sset Headphone 100% unmute
	amixer -c 0 sset Speaker 100% unmute
	aplay /usr/share/orage/sounds/Phone.wav

	alsactl restore
	exit 1

With THRESHOLD= 7000 the audio file began to play every minute. Then I change it to THRESHOLD= 1200. And now the file plays though the battery is at 2200 mA. The script is not faulty. How can I tell cron that the file is a new one?

michaelk · 08-01-2015, 03:01 PM

The description indicates the file name as b1.sh but your actual file name is b102.sh Does the script name match the cron job?

What editor are you using to modify the file? Are you saving the file each time you change the THRESHOLD value? Are you exiting the editor each time you change value? You can keep the editor open but you need to save the file or the value will not be updated.

stf92 · 08-01-2015, 03:53 PM

The file names match. But I wrote THRESHOLD instead of $THRESHOLD. That was the error. Sorry for that. I edited with 'crontab -e'. By the way, the editor says the file name is /var/spool/cron/crontab.7Te3U. When exiting the editor, this file does not exist. Instead it writes /var/spool/cron/crontabs/root, which is the file I wanted to edit. Funny thing, isn't it?

michaelk · 08-01-2015, 05:08 PM

Variable assignments do not have a $. Look at a1 and current_level.

Editing blo2.sh and editing a cron job are separate unrelated processes. I was trying to determine if you kept the editor opened while you tried changing values? If you did not save the file the new value is not used.

stf92 · 08-01-2015, 06:12 PM

No, I first closed the file and exited the editor. Thanks.