Commands that use a line range:
If no line is given, then curent line is printed.

p	Print line.
d	Delete line.
l	Print line with control characters.
r file	Read in a file after the line specified.
s	Substitute patterns. See special documentation.
z	Print 10 lines.
a	Start insert mode after specified line.
i	Start insert mode before specified line.

Commands used without line specification:

q	Quit. Won't work if file is changed.
Q	Quit and discard all changes if not saved.
w	Write the file out.
e file	Edit a file.
!cmd	Give a game command. For example "say Wait, I am busy".

As line numbers '.' is current line, and '$' is last line of file.
Thus '1,$p' will always print all of the file.