^-R will do a reverse-search through your command history. This
is very useful.
+You can also review your recent commands with the `history` command. Just enter:
+
+ history
+
+to see a numbered list of recent commands, including this just issues
+`history` command. You can reuse one of these commands directly by
+referring to the number of that command.
+
+If your history looked like this:
+
+ 259 ls *!
+ 260 ls /usr/bin/*.sh
+ 261 ls *4*1
+
+then you could repeat command #260 by simply entering:
+
+ !260
+
+(that's an exclamation mark).
+
+* * * *
+**Short Exercise**
+
+1. Find the line number in your history for the last exercise (listing
+files in /bin) and reissue that command.
+
+* * * *
+
## Which program?
Commands like `ls`, `rm`, `echo`, and `cd` are just ordinary programs