WTERMSIG

WTERMSIG is a macro defined in the system header associated with process status information, used when inspecting the status value returned by wait or waitpid. It yields the termination signal number that caused a child process to terminate, and its result is meaningful only when WIFSIGNALED(status) is true.

In typical usage, a program calls wait or waitpid to obtain a status integer. The macro WIFSIGNALED(status) is checked to determine whether the child was terminated by a signal. If so, WTERMSIG(status) provides the specific signal number that terminated the process, which can then be reported or acted upon accordingly. For example, after waitpid, if (WIFSIGNALED(status)) { int sig = WTERMSIG(status); /* handle termination by sig */ }.

WTERMSIG is used in conjunction with other macros that interpret the status value, such as WIFEXITED (normal termination) and WEXITSTATUS (exit code), or WIFSTOPPED (process stopped). It is complementary to these macros and helps distinguish the cause of termination.

Portability and headers: WTERMSIG is defined by POSIX and is available on systems that conform to POSIX wait/status conventions, including most Unix-like systems such as Linux, BSD variants, and macOS. The relevant macros are declared in headers such as <sys/wait.h> or <wait.h> depending on the system.

Notes: WTERMSIG reflects the signal responsible for termination but does not by itself indicate whether a core dump occurred; use WCOREDUMP(status) to check for a core dump when the child was terminated by a signal. It is important to verify WIFSIGNALED(status) before using WTERMSIG(status). See also WIFEXITED, WEXITSTATUS, WIFSTOPPED, WCONTINUED, and wait/waitpid.