Shell Expansion

Definitions

1. The series of transformations the shell applies to a command line before execution — including brace expansion (`{a,b}`), tilde expansion (`~`), parameter/variable expansion (`$VAR`), command substitution (`$(cmd)`), arithmetic expansion, word splitting, and pathname (glob) expansion (`*.txt`).

   In plain English: The process where the shell automatically replaces shortcuts like `*`, `$VAR`, and `~` with their actual values before running a command.

   Example: "The unquoted variable caused word splitting during shell expansion, turning one filename with spaces into three separate arguments."

Related Terms

• Exit Code
• Export
• Field Separator
• Here Document
• Pipe
• Redirection
• Shell Builtin
• Shell Variable