"It is generally a good idea to enclose variable calls in double quotation marks". No, it's generally a good idea to learn what quotes do and use the appropria

"It is generally a good idea to enclose variable calls in double quotation marks". No, it's generally a good idea to learn what quotes do and use the appropriate kind when required. Else you're just adding noise to your code. The backslashes aren't needed in listing 9 since the shell expects more input after `&&' or `||' and automatically switches to PS2. Using xargs is more subtle than they suggest. If may kick off the given command multiple times. This would make a difference, e.g. `xargs wc' would give multiple totals.