Added some smallish comments to help folks understand why we have two tables
of builtins and the reasoning behind it.
diff --git a/sh.c b/sh.c
index 4620ae3..bb258c7 100644
--- a/sh.c
+++ b/sh.c
@@ -112,7 +112,9 @@
static int busy_loop(FILE * input);
-/* Table of built-in functions */
+/* Table of built-in functions (these are non-forking builtins, meaning they
+ * can change global variables in the parent shell process but they will not
+ * work with pipes and redirects; 'unset foo | whatever' will not work) */
static struct builtInCommand bltins[] = {
{"bg", "Resume a job in the background", "bg [%%job]", builtin_fg_bg},
{"cd", "Change working directory", "cd [dir]", builtin_cd},
@@ -125,7 +127,8 @@
{NULL, NULL, NULL, NULL}
};
-/* Table of built-in functions */
+/* Table of forking built-in functions (things that fork cannot change global
+ * variables in the parent process, such as the current working directory) */
static struct builtInCommand bltins_forking[] = {
{"env", "Print all environment variables", "env", builtin_env},
{"pwd", "Print current directory", "pwd", builtin_pwd},