Chaining Two Commands

Now that you understand what a pipe does, let's see how to use it effectively with two commands. The key is choosing commands that work well together, where the output of the first makes sense as input for the second.

A common pairing is ls with wc -l to count files:

ls | wc -l

The ls command lists files (one per line), and wc -l counts those lines. The result is the number of files in the current directory.

Another useful combination is cat with head to preview a file:

cat longfile.txt | head -5

This displays only the first 5 lines of the file. You could also use head -5 longfile.txt directly, but piping becomes essential when the first command generates output that isn't simply reading a file.

For example, combining ls -l with head:

ls -l | head -3

This shows detailed information for just the first few items in a directory. The pipe transforms two simple commands into a more powerful operation.