To display the first 10 lines of a file:
This displays the first 10 lines of the file vi.txt which is in the directory /usr/local/doc/
To display the first 5 lines of several files:
head -5 *.xdh
This displays, one after the other, the first 5 lines of each file with the extension .xdh in the current directory.
The first line of each file is shown as:
==> filename <==