Learn Linux Shell Scripting - Fundamentals of Bash 4.4

/opt/, /tmp/, and /var/

On a fresh installation of Ubuntu, the /opt/ directory is empty. While it is again a matter of convention, in our experience, this directory is most often used to install software that comes from outside the distribution's package manager. However, some applications that are installed with the package manager do use /opt/ for their files; it's all a matter of preference by the package maintainer. In our case, we will be using this directory to save the shell scripts we'll be creating, as these definitely classify as optional software.

The /tmp/ directory is used for temporary files (who would have guessed?). In some Linux distributions, /tmp/ is not part of the root partition but mounted as a separate tmpfs filesystem. ...