#### b.1) How to use the output of one command as the input to another with a pipe...
A special kind of redirection is called a pipe and is denoted by `|`.
-### f) That combining single-purpose filters with pipes is the most productive way to use the shell...
-### g) That if a program conforms to Unix conventions, it can easily be combined with others...
+| Command | Description |
+|---------|-------------------------------------------------------------------------------------------------------------------------------------------------------|
+| `|` | Output from one command line program can be used as input to another one (e.g. `ls *.md | head` gives you the first 5 `*.md` files in your directory) |
+* Combining single-purpose filters with pipes is the most productive way to use the shell...
+ * a program conforms that to Unix conventions, it can easily be combined with others...
+
+Example:
+
+ ls *.md | head | sed -i `s/markdown/software/g`
+
+changes all the instances of the word `markdown` to `software` in the first 5 `*.md` files in your current directory.
## 4. Variables