Args0

Args0 is an informal term used in programming to denote the first element of a program’s argument vector, typically the invocation name of the program. It is often represented as argv[0] in C and similar languages and is sometimes called the program name or invocation name. The exact contents of args0 vary by language and environment.

In C and C-like environments, argv[0] usually contains the path or name used to execute the program. In Python, sys.argv[0] is the path to the script being run. In Node.js, process.argv[0] is the path to the Node interpreter, while the script name is in process.argv[1]. In Bash and similar shells, the special parameter $0 expands to the name of the shell or the script being executed. Because of these differences, args0 is not a universal concept and should be interpreted within the specific language or runtime.

Common uses of args0 include displaying the program name in usage or help messages, tagging output for logs, and helping with simple dispatch logic based on how the program was invoked. It can also be useful for error reporting or diagnostics. However, there are caveats: argv[0] can be set in nonstandard ways, can be a symlink or an alias, and in some environments may be empty or reflect the interpreter rather than the script. Therefore, relying on args0 for strict file identification or behavior can be brittle; languages often provide additional means to locate a script’s actual path or to normalize program identification independently of how it was invoked.