finished notes

_subsections/lesson-01.org

@@ -106,4 +106,29 @@
 the output will be
 =/home/ronny/programs/notes/courses=
 
+** permissions
+*** groups of three
+- read
+- write
+- execute
 
+*** directories
+- read: are you allowed to see the files
+- write: can you rename the files in the directory
+- execute: "search" are you allowed to enter this directory
+  - to access a file in a directory, you need execute permissions on all directories in the path
+
+** piping
+- every program has two streams
+  - input stream
+  - output stream
+- shell allows you to change streams
+  - angle brackets
+  - left angle < : rewire input
+  - right angle > : rewire output
+
+- example
+  #+begin_src bash
+   echo hello > hello.txt
+   cat < hello.txt
+  #+end_src