diff --git a/_subsections/lesson-04.org b/_subsections/lesson-04.org
index 407ac07..aac8e2e 100644
--- a/_subsections/lesson-04.org
+++ b/_subsections/lesson-04.org
@@ -10,7 +10,7 @@
- [[https://www.youtube.com/playlist?list=PLyzOVJj3bHQuloKGG59rS43e29ro7I57J][Playlist: Missing Semester]]
- [[https://missing.csail.mit.edu/2020/data-wrangling/][class notes]]
-- Curr: https://youtu.be/sz_dsktIjt4?si=oVhYD6bPPM6FzWSL&t=1325
+- Curr: https://youtu.be/sz_dsktIjt4?si=XopbHGTFXY-I6Bkh&t=2577
*** timestamps
:PROPERTIES:
@@ -28,7 +28,7 @@
+ [[https://www.youtube.com/watch?v=sz_dsktIjt4&t=776s][12:56 - Alternations]]
+ [[https://www.youtube.com/watch?v=sz_dsktIjt4&t=1029s][17:09 - Anchoring the Regular Expression]]
+ [[https://www.youtube.com/watch?v=sz_dsktIjt4&t=1138s][18:58 - Capture Groups]]
-+ [[https://www.youtube.com/watch?v=sz_dsktIjt4&t=1215s][20:15 - Regular Expression Debugger]] *current*
++ [[https://www.youtube.com/watch?v=sz_dsktIjt4&t=1215s][20:15 - Regular Expression Debugger]]
+ [[https://www.youtube.com/watch?v=sz_dsktIjt4&t=1450s][24:10 - Regular Sessions]]
+ [[https://www.youtube.com/watch?v=sz_dsktIjt4&t=1561s][26:01 - Match and Email Address ]]
+ [[https://www.youtube.com/watch?v=sz_dsktIjt4&t=1743s][29:03 - Sort]]
@@ -36,8 +36,8 @@
+ [[https://www.youtube.com/watch?v=sz_dsktIjt4&t=2324s][38:44 - Berkeley Calculator]]
+ [[https://www.youtube.com/watch?v=sz_dsktIjt4&t=2437s][40:37 - Computer Statistics over Inputs]]
+ [[https://www.youtube.com/watch?v=sz_dsktIjt4&t=2482s][41:22 - Summary Statistics]]
++ [[https://www.youtube.com/watch?v=sz_dsktIjt4&t=2570s][42:50 - Two sort of special types]] *current*
+ [[https://www.youtube.com/watch?v=sz_dsktIjt4&t=2513s][41:53 - Plotting]]
-+ [[https://www.youtube.com/watch?v=sz_dsktIjt4&t=2570s][42:50 - Two sort of special types]]
+ [[https://www.youtube.com/watch?v=sz_dsktIjt4&t=2754s][45:54 - example where data wrangling is useful]]
+ [[https://www.youtube.com/watch?v=sz_dsktIjt4&t=2805s][46:45 - image captures to standard output]]
+ [[https://www.youtube.com/watch?v=sz_dsktIjt4&t=2846s][47:26 - operate on standard input]]
@@ -76,3 +76,30 @@ sed 's/.*blahblah blah//'
** regex debugger
- regex101.com
+
+** sort
+- can sort by column
+- sorts ascending by default
+
+** awk
+- programming language
+- focused on columnar data
+- can match by pattern
+
+** paste
+- takes input and puts it together how you want
+- '-s' :: single line
+- '-d' :: delimiter
+
+** berkley calculator
+- calculator that reads from stdin
+
+** compute statistics
+- R language is built for statistical analysis
+
+** gnuplot
+- plotter
+- takes from stdin
+
+** xargs
+- takes lines of input and puts them into arguments
diff --git a/_subsections/lesson-05.org b/_subsections/lesson-05.org
new file mode 100644
index 0000000..0a1482f
--- /dev/null
+++ b/_subsections/lesson-05.org
@@ -0,0 +1,39 @@
+#+title: Lesson 05 | Command line Environment
+#+HTML_HEAD:
+#+HTML_HEAD:
+#+HTML_HEAD:
+#+OPTIONS: H:6
+
+* Links
+#+attr_html: :class links
+- [[../toc.org][TOC | Missing Semester]]
+- [[https://www.youtube.com/playlist?list=PLyzOVJj3bHQuloKGG59rS43e29ro7I57J][Playlist: Missing Semester]]
+- [[https://www.youtube.com/redirect?event=video_description&redir_token=QUFFLUhqbVVJc2RzZ25nMmlrVW5zVGRsTS1fX2ladmRPQXxBQ3Jtc0ttWjQ5Ujcyd19TekNncTZGNEp1eDc3RWhzTzhvMW9oSTFoUl9JbGt1Mi0yU3FLc00wVUx1UXNJdFQxTjBjMWphdUZxNnU1WUYzTmFqd3RRemNLUDBJMlZkV3B0SnB4RVhpaUhvWWtnc1RISW1WVzdYWQ&q=https%3A%2F%2Fmissing.csail.mit.edu%2F2020%2Fcommand-line%2F&v=e8BO_dYxk5c][class notes]]
+
+- Curr: https://youtu.be/sz_dsktIjt4?si=XopbHGTFXY-I6Bkh&t=2577
+
+*** timestamps
+:PROPERTIES:
+:CUSTOM_ID: timestamp
+:END:
+
+#+attr_html: :class playlist
++ [[https://youtu.be/e8BO_dYxk5c?si=A-imhHunQCtp_-Oz][00:00 - introduction]]
++ [[https://www.youtube.com/watch?v=e8BO_dYxk5c&t=138s][02:18 - Job Control]]
++ [[https://www.youtube.com/watch?v=e8BO_dYxk5c&t=227s][03:47 - Signal Interrupts]]
++ [[https://www.youtube.com/watch?v=e8BO_dYxk5c&t=360s][06:00 - Python Program]]
++ [[https://www.youtube.com/watch?v=e8BO_dYxk5c&t=672s][11:12 - The Kill Command]]
++ [[https://www.youtube.com/watch?v=e8BO_dYxk5c&t=881s][14:41 - Terminal Multiplexer]]
++ [[https://www.youtube.com/watch?v=e8BO_dYxk5c&t=1112s][18:32 - The Key Bindings]]
++ [[https://www.youtube.com/watch?v=e8BO_dYxk5c&t=1536s][25:00 - Dot Files]]
++ [[https://www.youtube.com/watch?v=e8BO_dYxk5c&t=1799s][29:59 - Context Based Configuration File]]
++ [[https://www.youtube.com/watch?v=e8BO_dYxk5c&t=2004s][33:24 - Terminal Emulator]]
++ [[https://www.youtube.com/watch?v=e8BO_dYxk5c&t=2196s][36:36 - Aliases]]
++ [[https://www.youtube.com/watch?v=e8BO_dYxk5c&t=2286s][38:06 - Common Folder Structure]]
++ [[https://www.youtube.com/watch?v=e8BO_dYxk5c&t=2344s][39:04 - Symlinks]]
++ [[https://www.youtube.com/watch?v=e8BO_dYxk5c&t=2552s][42:32 - ssh]]
++ [[https://www.youtube.com/watch?v=e8BO_dYxk5c&t=2715s][45:15 - ssh keys]]
++ [[https://www.youtube.com/watch?v=e8BO_dYxk5c&t=3057s][50:57 - ssh config]]
++ [[https://www.youtube.com/watch?v=e8BO_dYxk5c&t=3231s][53:51 - changing the prefix]]
+
+* notes
diff --git a/toc.org b/toc.org
index 9b95791..0ddbae2 100644
--- a/toc.org
+++ b/toc.org
@@ -33,3 +33,4 @@
- [[./_subsections/lesson-02.org][Lesson 02 | Shell Tools and Scripting]]
- [[./_subsections/lesson-03.org][Lesson 03 | Editors (vim)]]
- [[./_subsections/lesson-04.org][Lesson 04 | Data Wrangling]]
+- [[./_subsections/lesson-05.org][Lesson 05 | Command-line Environment]]