terminated children do not become zombies on Linux

signal(SIGCHLD, SIG_IGN);
https://man7.org/linux/man-pages/man2/sigaction.2.html

POSIX.1-1990 disallowed setting the action for SIGCHLD to
SIG_IGN.  POSIX.1-2001 and later allow this possibility, so that
ignoring SIGCHLD can be used to prevent the creation of zombies
(see wait(2)).  Nevertheless, the historical BSD and System V
behaviors for ignoring SIGCHLD differ, so that the only
completely portable method of ensuring that terminated children
do not become zombies is to catch the SIGCHLD signal and perform
a wait(2) or similar.

Author: yiwu0b11

flang/runtime/execute.cpp

@@ -21,6 +21,7 @@
 #include <stdio.h>
 #include <windows.h>
 #else
+#include <signal.h>
 #include <unistd.h>
 #endif
 
@@ -223,6 +224,8 @@ void RTNAME(ExecuteCommandLine)(const Descriptor *command, bool wait,
     }
     delete[] wcmd;
 #else
+    // terminated children do not become zombies
+    signal(SIGCHLD, SIG_IGN);
     pid_t pid{fork()};
     if (pid < 0) {
       if (!cmdstat) {