shellTrue

ShellTrue is a term used in some discussions of shell scripting to denote a portable construct that yields a boolean true value in shell environments. It is not a standard feature of POSIX shells, and there is no official specification. Instead, it refers to a small utility, function, or convention that can be used to obtain a truth value in a way that is easy to consume in scripts across different shells.

A typical implementation is a tiny script or function that exits with status 0, indicating success, and may optionally print a canonical string such as "true" to standard output. The exact behavior varies: some variants print the word true, others produce no output and rely solely on the exit status. The value can be used in conditionals, for example "if shellTrue; then ...; fi", or captured in a variable with "val=$(shellTrue)" and then compared.

Because ShellTrue lacks standardization, practitioners often prefer native tools such as the true command (which exits with status 0 and emits no output) or explicit tests in POSIX shells for portability. A textual wrapper can help unify interfaces when a script expects a string, but it introduces an extra dependency and possible portability concerns.

In practice, the concept functions best as a documentation or teaching aid to discuss how different shells treat booleans and command success versus textual values.

See also: true command; test; POSIX shell; boolean logic in shell scripting.