I'm running Ubuntu 12.04 and bash. I've written a pair of shell scripts that allow me to set an alarm which, after ringing, unsets itself. The first, alarmset, allows me to enter a time and modifies the alarm line in my user crontab. That line launches the second script, alarmring, which launches a radio player in a browser window and then comments out the alarm line in the crontab.
alarmring is behaving strangely. If I run it myself directly, it performs both actions: it launches the browser window and edits the crontab. But if I run alarmset, when the crontab launches alarmring at the appointed time, alarmring edits the crontab, but does not launch the browser window.
Finally, when crontab runs alarmring, it ignores the set -x command, whereas when I run it directly, set -x is executed. So it's as though the crontab is skipping the first ten lines.
Any ideas on what's going on? I'll paste the two scripts and the crontab below.
alarmset:
#!/bin/bash
# alarmset
set -x
usage()
{ echo "alarmset [ hour minute | -h ]" }
editcrontab()
{
echo $'/alarmring/s/^\(.*\)\(\* \* \*\)/'$2$' '$1$' \\2/' > ~/Documents/crontab_script.txt
crontab -l | sed --file=/home/username/Documents/crontab_script.txt > ~/Documents/new_crontab.txt crontab ~/Documents/new_crontab.txt
}
### MAIN
case $# in
2 ) editcrontab $1 $2 ;;
* ) usage
exit ;;
esac
set +x
alarmring:
#!/bin/bash
# alarmring
set -x
env DISPLAY=:0
# Ring the alarm : launch BBC World Service in Firefox
firefox --new-window http://www.bbc.co.uk/radio/player/bbc_world_service
# Unset the alarm : comment out the alarm line in the crontab
crontab -l | sed '/alarmring/s/^/#/1' > ~/Documents/new_crontab.txt
crontab ~/Documents/new_crontab.txt
set +x
crontab:
SHELL=/bin/bash
PATH=~/bin:/usr/bin:/bin
#
# m h dom mon dow command
53 07 * * * /home/username/bin/alarmring
