getconf

getconf is a Unix utility that queries runtime system configuration values as exposed by the C library. It is standardized in POSIX and is available on many Unix-like systems, including Linux, macOS, and BSD variants. The program reads values that influence program behavior and resource limits without requiring the inclusion of header files.

Usage: The general syntax is getconf [ -a ] name [ pathname ]. The name identifies a configuration variable, often corresponding to sysconf() or pathconf() limits or options, or to library-defined constants such as _POSIX_VERSION or LONG_BIT. The -a option prints all supported names. If a pathname is supplied, the returned value reflects the configuration for that directory; otherwise the system-wide value is used.

Examples: getconf LONG_BIT prints 64 on a 64-bit system. getconf PATH_MAX prints the maximum length of a path name. getconf _POSIX_VERSION may print the POSIX version supported by the C library.

Notes: Not all variables are defined on all systems; unknown names cause an error. The values are produced by the system's sysconf and pathconf interfaces and vary with architecture, OS, and library implementation. getconf can output numeric values or strings, depending on the variable.

See also: sysconf, pathconf, confstr, limits.h.