crontab cannot find environment variable even after sourcing .bashrc

Question

crontab -e

00 00 * * * /home/username/run.sh >> /home/username/log 2>&1

Inside run.sh:

source /home/username/.bashrc
java

When crontab job is triggered, I got this error in the log:

/home/username/run.sh: 1: /home/username/run.sh: java: not found

However, java path is set in /home/username/.bashrc, so I was expecting sourcing should set the java path:

I know I can fix it by:

export PATH="/usr/local/jdk1.8.0_231/bin:$PATH"
java

But why sourcing .bashrc is not enough? What environment variables does crontab have exactly and what does source .bashrc do exactly (so that crontab doesn't take it into account)?

Thanks.

Answer 1

I have some guessing but may be wrong:

• when we open a bash shell, we start a bash process, and when running .bashrc, it makes change to the environment of this bash process only
• crontab has its own process that has no relation to the bash process opened
• when sourcing .bashrc, it only makes changes to bash process (though there's none when running crontab??), therefore crontab still does not have any change to the environment variable

Therefore, sourcing .bashrc doesn't help crontab.