valgrind

Check for memory leaks

$ valgrind --leak-check=full [./program]

$ valgrind --leak-check=full --show-leak-kinds=all [./program]

$ valgrind --track-origins=yes [./program]

$ valgrind --tool=cachegrind [./program]

$ valgrind --tool=callgrind [./program]

$ valgrind --tool=helgrind [./program]

$ valgrind --gen-suppressions=all [./program]

valgrind [--tool=toolname] [options] program [args]

valgrind is an instrumentation framework for dynamic analysis tools. The default tool, memcheck, detects memory management problems: leaks, use of uninitialized memory, buffer overflows, and invalid frees.
Programs run significantly slower under Valgrind (10-50x) as every memory access is instrumented. This is normal and expected.
Output indicates error type, location (with line numbers if compiled with -g), and call stack. "Definitely lost" memory is a real leak; "still reachable" may be acceptable cleanup deferred to exit.
Other tools profile performance (cachegrind, callgrind), detect threading issues (helgrind, drd), or analyze heap usage (massif).

--tool=name

Select tool (memcheck, cachegrind, callgrind, helgrind, drd, massif)

Check for memory leaks (no, summary, full)

Which leaks to show (definite, indirect, possible, reachable, all)

Track origins of uninitialized values

Write output to file

Output in XML format

Generate suppression entries (no, yes, all)

Use suppressions from file

More verbose output

Less verbose output

memcheck: Memory error detector (default)
cachegrind: Cache and branch profiler
callgrind: Call-graph profiler
helgrind: Thread error detector
drd: Thread error detector (different algorithm)
massif: Heap profiler

Compile programs with -g for line numbers and -O0 or -O1 for accurate debugging (high optimization confuses source mapping).
False positives occur, especially with system libraries. Use suppression files to ignore known issues.
Valgrind doesn't work well with JIT compilers or custom memory allocators without additional configuration.

gdb(1), strace(1), ltrace(1), asan(7)