\section{Page Manipulation Commands} \label{Page Manipulation Commands} The following commands permit text to be read into the text buffer from an input file or written from the buffer onto an output file. All of the input commands listed in this table assume that the input file is organized into pages small enough to fit into available memory. If any page of the input file contains more characters than will fit into available memory, the input command will continue reading characters into the buffer until a line feed is encountered when the buffer is about 3/4 full. See the appendices for more details. Special techniques for handling pages larger than the buffer capacity will be presented later in this chapter. \begin{table}[h] \caption{\bf Page Manipulation Commands} \end{table} \nopagebreak \subsection*{APPEND commands} \begin{list}{}{\labelsep 20pt} \medskip \item [{\tt A}] Appends the next page of the input file to the contents of the text buffer, thus combining the two pages of text on a single page with no intervening form feed character. This command takes no argument. To perform {\tt n} Appends, use the {\tt n} construct. Note that {\tt nA} is a completely different command. \ifnotintecoeight \item [{\tt :A}] Equivalent to the {\tt A} command except that a value is returned. -1 is returned if the append succeeded, and 0 is returned if the append failed because the end-of-the-input-file had previously been reached (\caret {\tt N} flag is -1 at start of this command). {\em [Not in TECO-8]} \item [{\tt n:A}] Appends {\tt n} lines of text from the input file to the contents of the text buffer. The value of {\tt n} must not be negative. A value is returned indicating whether or not there were in fact n lines remaining in the input file. -1 is returned if the command succeeded. 0 is returned if end-of-file on the input file was encountered before all n lines were read in. Note that the command can succeed and yet read in fewer than {\tt n} lines in the case that the text buffer fills up. {\em [Not in TECO-8]} \fi \subsection*{PAGE Commands} \item [{\tt P}] Writes the contents of the buffer onto the output file, then clears the buffer and reads the next page of the input file into the buffer. A form feed is appended to the output file if the last page read in (with a {\tt P}, {\tt Y}, or {\tt A} command) was terminated with a form feed. \ifnotintecoeight \item [{\tt :P}] Same as the {\tt P} command except that a value is returned. -1 is returned if the command succeeded. 0 is returned if the command failed because the end-of-file on the input file had been reached prior to the initiation of this command. The command string {\tt <:P;>} takes you to end of file. {\em [Not in TECO-8]} \fi \item [{\tt nP}] Executes the {\tt P} command {\tt n} times, where n must be a non-zero positive integer. In TECO-11 on VAX/VMS, n can be a negative integer (and {\tt -P} means {\tt -1P}). A {\tt -nP} command will back up {\tt n} pages. \ifnotintecoeight \item [{\tt n:P}] Executes the {\tt :P} command {\tt n} times, where {\tt n} must be a non-zero positive integer. In TECO-11 on VAX/VMS, n can be a negative integer (and {\tt -:P} means {\tt -1:P}). This command returns 0 when another page could not be backed up because beginning of file had been reached. {\em [Not in TECO-8]} \fi \item [{\tt PW}] Write the contents of the buffer onto the output file and append a form feed character. The buffer is not cleared and the pointer position remains unchanged. \item [{\tt nPW}] Executes the {\tt PW} command {\tt n} times, where {\tt n} must be a non-zero positive integer. \item [{\tt m,nPW}] Writes the contents of the buffer between pointer positions {\tt m} and {\tt n} onto the output file. {\tt m} and {\tt n} must be positive integers. A form feed is not appended to this output, nor is the buffer cleared. The pointer position remains unchanged. \item [{\tt m,nP}] Equivalent to {\tt m,nPW}. \item [{\tt HPW}] Equivalent to the {\tt PW} command except that a form feed character is not appended to the output. \item [{\tt HP}] Equivalent to {\tt HPW}. \subsection*{YANK commands} \item [{\tt Y}] Clears the text buffer and then reads the next page of the input file into the buffer. Because the {\tt Y} command DESTROYS the current text buffer, its use can result in the loss of data, and is subject to {\em Yank protection} (see {\tt ED} flag in section~\ref{Conditional Execution Commands}). % \ifvmstrue \item [{\tt -Y}] Clears the text buffer and then reads the previous page of the file being edited back into the buffer. Because the {\tt Y} command DESTROYS the current text buffer, its use can result in the loss of data, and is subject to {\em Yank protection} (see {\tt ED} flag in section~\ref{Conditional Execution Commands}). {\em [TECO-11 on VAX/VMS only]} % \fi \ifnotintecoeight \item [{\tt :Y}] Same as the {\tt Y} command but a value is returned. -1 is returned if the Yank succeeded. 0 is returned if the Yank failed because the end-of-file had been reached on the input file prior to the initiation of this command. {\em [Not in TECO-8]} \fi \item [{\tt -:Y}] Same as the {\tt -Y} command but a value is returned. -1 is returned if the Yank succeeded. 0 is returned if the Yank failed because the beginning of file had been reached on the file being edited prior to the initiation of this command. {\em [TECO-11 on VAX/VMS only]} \item [{\tt EY}] Same as the {\tt Y} command, but its action is always permitted regardless of the value of the Yank Protection bit in the {\tt ED} flag. Remember that Yank DESTROYS the current buffer; there's no way to get it back! \ifnotintecoeight \item [{\tt :EY}] Same as the {\tt :Y} command, but its action is always permitted regardless of the value of the Yank protection bit in the {\tt ED} flag. Remember that Yank DESTROYS the current buffer; there's no way to get it back! {\em [Not in TECO-8]} \fi \end{list}