постраничная основа (by-page basis)
Стандартный вывод сообщений (Stderr)
The standard error shall be used for diagnostic messages and user
commands (see the INPUT FILES section), and, if standard output
is a terminal device, to write a prompting string. The prompting
string shall appear on the screen line below the last line of the
file displayed in the current screenful. The prompt shall contain
the name of the file currently being examined and shall contain
an end-of-file indication and the name of the next file, if any,
when prompting at the end-of-file. If an error or informational
message is displayed, it is unspecified whether it is contained
in the prompt. If it is not contained in the prompt, it shall be
displayed and then the user shall be prompted for a continuation
character, at which point another message or the user prompt may
be displayed. The prompt is otherwise unspecified. It is
unspecified whether informational messages are written for other
user commands.
