LSANOPTIONS

LSANOPTIONS is commonly recognized as an environment variable used to configure LeakSanitizer, the leak-detection component of the LLVM sanitizers suite. The canonical variable name is LSAN_OPTIONS, and LSANOPTIONS (without the underscore) is sometimes encountered in documentation, scripts, or misuse, but programs that rely on LeakSanitizer typically read LSAN_OPTIONS. The variable enables fine-grained control over leak detection behavior and reporting without requiring recompilation.

The variable contains a colon-separated list of key=value options that the LeakSanitizer runtime interprets at startup. Options influence what leaks are detected, how much detail is reported, and when checks are performed. Typical options include enabling or disabling leak detection, turning on origin tracking to identify where a leaked allocation originated, controlling the level of verbosity, and directing where logs are written. Many installations also support suppressions files, leak-check-at-exit flags, limits on reported leaks, and log paths. Because the exact set of options can vary by version, it is common to consult the specific toolchain’s documentation for the precise keys available.

Examples: exporting LSAN_OPTIONS="verbosity=1:leak_check_at_exit=1" will increase diagnostic output and perform a leak check when the program exits. Another example sets a log path with LSAN_OPTIONS="log_path=/tmp/lsan.log:verbosity=2". These configurations apply to programs instrumented with LeakSanitizer and executed in environments that support the sanitizer.

Notes: LSAN_OPTIONS primarily applies to C and C++ programs built with Clang/LLVM sanitizers. It may be ignored on non-instrumented builds or with other toolchains. For broader behavior, LSAN_OPTIONS is often used in combination with ASAN_OPTIONS or other sanitizer controls.