If you encounter an unfamiliar parameter expansion in a Bash script, which manual page should you consult for more information?

• A. man grep
• B. man bash
• C. man echo
• D. man sh

Answer: (B)

Parameter expansion is a feature of the Bash shell that lets you manipulate variables as a script runs. When you encounter unfamiliar syntax like ${var:-default}, ${var#pattern}, or ${array[@]}, the best place to look is the Bash manual. Open man bash and find the section on Shell Parameter Expansion; it details how Bash handles simple expansions, default values, pattern substitutions, slicing, arrays, and more. It also covers related expansions that Bash supports, which are not always present in other shells.

Other manuals describe specific commands (grep, echo, etc.) or a different shell's behavior (sh). Those won’t fully explain Bash’s variable expansion rules, especially the Bash-specific extensions. So consulting the Bash manual provides the most accurate and complete explanation for unfamiliar parameter expansions in a Bash script.