\frametitle{Building Pipes Step-by-Step}
\begin{block}{Progressive Example}
\begin{verbatim}
# 1. See all lines
$ cat app.log
ERROR: connection failed
INFO: started successfully
ERROR: timeout

# 2. Filter errors only
$ cat app.log | grep ERROR
ERROR: connection failed
ERROR: timeout

# 3. Count errors
$ cat app.log | grep ERROR | wc -l
2
\end{verbatim}
\end{block}
