Dashprefixed

Dashprefixed is a term used in computing to describe a token, argument, or string that begins with a dash character (-). In command-line interfaces, dash-prefixed items are commonly interpreted as options or flags rather than positional operands. Examples include -h and --help. Short options typically use a single dash with a single letter, and multiple short options can be combined as -abc to represent -a -b -c. Long options use a double dash, such as --output.

Parsing behavior for dash-prefixed tokens varies by platform and library. Most Unix-like tools follow POSIX and GNU conventions: a double dash signal, --, marks the end of option processing, after which subsequent arguments are treated as operands. Some contexts must distinguish between dash-prefixed strings that are options and those that are negative numbers or other data; parsers may require the explicit end-of-options marker to disambiguate.

In programming languages, dash-prefixed tokens appear in argument parsers to denote command-line flags. Libraries such as getopt, getopt_long, argparse, and various language-specific UI frameworks implement handling for dash-prefixed options. The term dashprefixed is descriptive rather than a formal keyword in language specifications, and it is commonly used in documentation and helper code to refer to tokens starting with a dash.

Differences across ecosystems exist: Windows Command Prompt often uses slash-prefixed options instead of dashes, while PowerShell employs its own parameter naming conventions with hyphens. See also: command-line interface, option flag, getopt, argparse.