Shell Programming and Scripting

I'm trying to run a alarm.sh using crontab, which play a song as
an alarm at 6.15 am. I'm using amixer so that volume increases by 10% in every loop.

My script is the following.

Code:

SHELL=/bin/bash
PLAYER=/usr/bin/mplayer
SONG=/home/hbar/Music/song.mp3
DISPLAY=:0.0

15 06 * * * /usr/bin/amixer sset Master 10%+ > /dev/null && $PLAYER -loop 5 $SONG > /dev/null 2>&1

However, nothing is happening! If I don't use amixer, song is played in the desired time.

(For testing I was changing the time to a time after 1 minute of the current time, so it's not that I need to wait till 6.15 am.)

Thanks.

I don't think you can specify variables in cron like that. You can only specify a few things like SHELL.

Also, what's your window manager? GNOME virally hijacks your file permissions via hooks in PAMD and other things, to control who gets permissions to use devices depending on your graphical login. Ergo you may not have permissions to access your sound device until you do a login, no matter what file permissions your sound devices are set to or what groups you belong to. (Or be given permissions without the proper groups or access, for that matter!)

Also, DISPLAY is not needed to play music. Specify -vo null so mplayer doesn't try to open one anyway and die when it can't get into your X context.

The percent sign (%) is a special character in a crontab command. From the man page

Given this, the command that you are executing isn't what you think it is. Try adding a back slant before the percentage: 10\%

All of Corona688's comments still apply.

@agama.

Putting a baclslash makes it work. Thanks. However, voume does not keep on increasing!

@Corona688

I'm using gnome desktop in ubuntu 12.04. I copied the structure from the internet and many places \dev\null is mentioned. Now, as I just said, it's working but volume is not increasing by 10% !

The way you have your command written, I wouldn't expect the volume to increase. The mixer command is invoked once, and if successful (&&) mplayer is invoked to play the mp3 looping through it 5 times.

If you want to bump the volume with each cycle through the file I would write a small script (alarm.bash or somesuch) and invoke that from cron. The script would look something like this:

Code:

#!/usr/bin/env bash
PLAYER=/usr/bin/mplayer
SONG=/home/hbar/Music/song.mp3

/usr/bin/amixer sset Master 35% >/dev/null 2>&1  # start with a default volume maybe??

for (( i = 0; i < 5; i++ ))
do
   /usr/bin/amixer sset Master 10%+ >/dev/null 2>&1
   $PLAYER -really-quiet -vo null $SONG >/dev/null 2>&1
done

In addition to Carona's suggestion, I'd toss in -really-quiet to cut the overhead of updates directed to /dev/null.

Are you meaning to execute from /etc/crontab? Can't I do it by

crontab <filename>.bash

?