Update fork_102.md (#151)

This include is needed ``` #include <unistd.h> ```
2021-09-15 03:49:07 -07:00 · 2021-09-15 03:49:07 -07:00 · ed85173a0b
commit ed85173a0b
parent 54ad724241
1 changed files with 5 additions and 4 deletions
--- a/exercises/os/fork_102.md
+++ b/exercises/os/fork_102.md
@ -4,6 +4,7 @@ Answer the questions given the following program (without running it):

 ```
 #include<stdio.h>
+#include <unistd.h> 

 int main()
 {