docs: Environment variables

Add more details to Environment variables section.

1 files changed, 16 insertions, 0 deletions

diff --git a/luxio.c b/luxio.c
index 27de64e..eaedec0 100644
--- a/luxio.c
+++ b/luxio.c
@@ -833,6 +833,10 @@ luxio_times(lua_State *L) /* 4.5.2 */
 */
 
 /*** Get an environment variable.
+
+Returns the value of the environment variable, or nil if the environment
+variable does not exist.
+
 @tparam string name
 @treturn string|nil return value
 @function getenv
@@ -853,6 +857,15 @@ luxio_getenv(lua_State *L) /* 4.6.1 */
 }
 
 /*** Set an environment variable.
+
+Returns zero on success, or -1 on error, with errno set appropriately.
+
+Add the variable with name `name` to the environment if it
+doesn't already exist. If it does already exist then overwrite
+it if `overwrite` is non-zero, otherwise do nothing.
+_Note: `setenv()` still returns successfully if the variable
+is found and `overwrite` is zero._
+
 @tparam string name
 @tparam string value
 @tparam[opt=0] number overwrite
@@ -874,6 +887,9 @@ luxio_setenv(lua_State *L) /* POSIX.1-2001 */
 }
 
 /*** Unsets an environment variable.
+
+Returns zero on success, or -1 on error, with errno set appropriately.
+
 @tparam string name
 @treturn number return value
 @treturn errno