Never assume a user's choice of line-text editor ($EDITOR), visual-text editor ($VISUAL), shell ($SHELL), or web browser ($BROWSER). Instead, fall back to sensible defaults if these values are not set, using the :- form of parameter expansion:
#!/bin/bash
read -p 'Now editing your configuration file (press ENTER): '
"${VISUAL:-vi}" -- "$HOME"/.myscriptrc
The preceding script will wait for an Enter key press (well, a line entry, technically). It then starts the user's choice of visual-text editor if it's set, or defaults to vi if it's not, which should be installed on most Unix-like systems. In some circumstances, such as a script for use by beginners, a more sensible default choice might be nano. Consider carefully what your script's users might expect to happen; avoid...
