WIFCONTINUEDstatus

WIFCONTINUEDstatus refers to the interpretation of a status value produced by wait-related system calls in POSIX-compliant operating systems. It describes the condition where a child process has resumed execution after being stopped, typically by a SIGCONT signal. The WIFCONTINUED macro tests a wait status to determine if such a continuation has occurred. This macro is part of the family of status-check macros used with wait, waitpid, and similar functions, alongside WIFEXITED, WIFSIGNALED, and WIFSTOPPED.

Usage and behavior

To detect continued processes, a program must call waitpid (or wait) with the WCONTINUED option enabled. If a child is continued from a stopped state, the resulting status value can be inspected with WIFCONTINUED(status). In that case, WIFCONTINUED evaluates to true, indicating a continuation event. It is important to note that WIFCONTINUED is only meaningful when the WCONTINUED flag is used in the wait call; without it, continued events may not be reported.

Relation to other status checks

WIFCONTINUED is one of several macros used to decode child status values. WIFSTOPPED indicates a child is currently stopped, WIFEXITED indicates normal termination, and WIFSIGNALED indicates termination by a signal. The corresponding status checks enable programs to implement robust job control and process management logic: they can distinguish between a process that has stopped, continued, or terminated and respond appropriately.

Compatibility and portability

WIFCONTINUED and the WCONTINUED option are defined in POSIX.1 and are widely supported on Linux, BSD, and macOS. Windows native APIs do not provide this macro, though compatible environments like Cygwin or MSYS2 may expose it. Developers targeting POSIX environments should include sys/wait.h and use waitpid with the WCONTINUED flag to rely on WIFCONTINUEDstatus.