Bash script behaving differently when executed from Crontab: Edit - Environment Variable issues with Pulseaudio

Question

I have a script that executes perfectly fine manually, though two commands in particular are completely ignored by Cron (this is just a snippet):

sinkint=$(pacmd list-sinks | sed -n '/index\W [1-9]/p' | sed 's/.*://g;s/\W//g')

pacmd set-default sink $sinkint
pacmd set-sink-volume $sinkint 20%

Crontab

* * * * * /path/to/script arg1 >> /path/to/log

Error messages

No PulseAudio daemon running, or not running as session daemon.
No PulseAudio daemon running, or not running as session daemon.
You have to specify a sink name/index and a volume

Edit:

tried variables in script

export PULSE_SERVER=unix:/tmp/pulse-socket
export PULSE_COOKIE=/tmp/pa_cookie

socket in my /etc/pulse/default.pa

load-module module-native-protocol-unix socket=/tmp/pulse-socket

socket and cookie in my /etc/pulse/client.conf

default-server = unix:/tmp/pulse-socket
cookie-file = /tmp/pa_cookie

crontab -e

PULSE_SERVER=unix:/tmp/pulse-socket
PULSE_COOKIE=/tmp/pa_cookie

* * * * * /path/to/script arg1 2> /path/to/log

Answer 1

adding XDG_RUNTIME_DIR=/run/user/1000 to crontab worked!

annoyingly... because it was literally the only enviroment variable that I needed. Oh well, if anybody needs the answer in the future - here it is I guess.

Answer 2

Jobs run through cron, or systemd startup scripts aren't run in the same runtime environment that you have on your desktop. systemd startup scripts are run as root. None of your PATH changes, or other environment variable settings from ~/.bashrc are automatically propagated to your cron job. For example, there's no $DISPLAY, so GUI programs need special treatment (read man xhost).

One can set environment variables for all one's cron jobs in the crontab file Read man 5 crontab.

Look at the results of echo "=== id ===";id;echo "=== set ===";set;echo "=== env ===";env | sort;echo "=== alias ===";alias in each of your environments.

Since the command part of the crontab line is, by default, interpreted by /bin/sh, which has a simpler syntax than /bin/bash, I recommend having command be a call to a bash script (executable, mounted, starts with #!/bin/bash) which sets up the environment, then calls the desired program.