Learn Linux Shell Scripting - Fundamentals of Bash 4.4

SHELL

It should be clear from looking at the outputs we saw for PATH, both at and cron by default use /bin/sh. You might get lucky and have a distribution where /bin/sh defaults to Bash, but this is not necessarily the case, especially not if you followed along with our Ubuntu 18.04 installation! In this case, if we check out /bin/sh, we see something different entirely:

reader@ubuntu:~$ ls -l /bin/shlrwxrwxrwx 1 root root 4 Apr 26  2018 /bin/sh -> dash

Dash is the Debian Almquist shell, which is the default system shell on recent Debian systems (Ubuntu, as you might remember, belongs to the Debian distribution family). While Dash is a wonderful shell with its own set of advantages and disadvantages, this book is written for Bash. So, for ...