\chapter{Command String Editing} \label{Command String Editing} \section{Immediate Action Editing Characters} \label{Immediate Action Editing Characters} While you are typing command strings at a terminal, TECO considers certain ASCII characters to have special meaning. Most of the special characters cause TECO to perform a specified function immediately, without waiting for the double {\tt } which normally be required to terminate a command string. Immediate action editing characters may be entered at any point in a command string -- even in the middle of a command or text argument. Many immediate action editing characters, such as {\tt } (which deletes the immediately preceding character), cannot be used as regular TECO commands. For instance, if you enter a {\tt } into a command string which is to be later executed as a macro, the {\tt } will not delete a character as part the execution of the macro. Some characters, like {\tt }, are both regular TECO commands and immediate action commands. The command string \caret {\tt Uqtext}\escape enters the {\tt text} into Q-register q. However, {\tt } typed while entering a command string is an immediate action editing character which deletes the current line. Thus you cannot type a {\tt } (or any similar sequence) directly into TECO as part of a command string. Nevertheless, {\tt } is still a valid TECO command; should TECO encounter it in a macro or indirect file, it will have its regular TECO effect (\caret {\tt Uqtext}\escape). Control characters used as immediate action editing characters must be entered using the \fbox{CONTROL} key; they will not be recognized if entered in their caret or up-arrow form. Table~\ref{Immediate Action Editing Characters} lists the immediate action editing characters and explains their functions. These characters take immediate effect and are used to edit a command string as it is being entered: \begin{table}[h] \caption{\bf{Immediate Action Editing Characters}} \end{table} \nopagebreak \begin{list}{}{\labelsep 20pt} \item [{\em CHARACTER}] {\em EXPLANATION} \item [{\tt }] The double {\tt } character sequence tells TECO to begin execution of the command string just typed in. It inserts two \escape s into the command string. ({\tt } may be generated by pressing a key designated by the user as an {\em ESCape surrogate} or by pressing an actual \fbox{ESCape} key. In the former case, \escape \escape is echoed; if no ESCape surrogate has been designated, {\tt \$\$} is echoed. See the {\tt EE} flag and the {\tt 8192 ET} bit, section~\ref{Mode Control Flags}, for more information.) The two {\tt }s must be typed successively. If any other character is typed in between the two {\tt }s (even if subsequently DELETEd), then the two {\tt }s might be treated simply as two {\tt }s to be entered into the command string rather than as an immediate action command. If you need to enter two {\tt }s into a command line, as in the case where you want to use the {\tt FSstring} \escape \escape command to delete a string, you can keep TECO from recognizing \escape \escape as an immediate action command. Type {\tt } and then continue entering the remainder of your command string. A single {\tt } character can also be an immediate action command (when typed immediately after TECO's prompting asterisk, see section~\ref{Immediate Action Commands}). Elsewhere, a single {\tt } performs no immediate action. \item [{\tt }] Typing a \fbox{DELETE} character \index{[DELETE] \fbox{DELETE}} (\fbox{DEL} or \fbox{RUBOUT} on some terminals) deletes the last character typed. DELETE can be typed repeatedly to erase multiple characters. TECO echoes the deleted character whenever a \fbox{DELETE} is typed, indicating to you that the character has been rubbed out. If you are doing your editing on a scope terminal, then the action of this key is different: the character that has been rubbed out will disappear from the screen of your editing terminal and the cursor will be moved back one position. If you delete a line feed, form feed, or vertical tab, the cursor will move up the screen and position itself at the end of the text that immediately preceded the line feed, form feed, or vertical tab. \item [{\tt }] {\tt } echoes as \caret {\tt C} \index{CTRL/C] \fbox{CTRL-C}} (Caret-{\tt C}) and aborts the entering of the command string. The exact action of the \fbox{CTRL/C} key depends on the operating system being used (See appendices). \item [{\tt }] {\tt } causes the current line \index{[CTRL-U] \fbox{CTRL-U}} of the current command line to be deleted. TECO echoes the character as \caret {\tt U} followed by {\tt } and an asterisk prompt. If you are using a scope terminal, the visible action of typing this key is different. The current line physically disappears from the screen and the cursor is positioned back at the beginning of the line. \item [{\tt }] \index{[CTRL-G] \fbox{CTRL-G}} Typing two consecutive {\tt } characters causes all commands which have been entered but not executed to be erased. (If the terminal has a bell, it will ring.) This command is used to erase an entire command string. A single {\tt } character is not a special character. \item [{\tt }] {\tt } followed by a space causes the line currently being entered into the command string to be retyped. \item [{\tt *}] {\tt } followed by an asterisk causes all the lines typed by the user from the last TECO prompt (the asterisk) to be retyped. \item [{\tt }] \index{[Return] \fbox{Return}} Typing a carriage return enters a carriage return followed by a line feed into the command string. To enter a carriage return without a line feed, type {\tt }. \item [{\tt }] \index{[CTRL-Z] \fbox{CTRL-Z}} RSX-11 TECO uses the triple {\tt } command as an immediate action command. See the appropriate appendix for more details. \end {list} The {\tt } character is used as an end-of-file terminator in some contexts on some operating systems. While its presence is usually harmless in disk files, it may cause premature end of file if the file is copied to other media (e.g., paper tape). \section{Immediate Action Commands} \label{Immediate Action Commands} The following commands take effect if (and only if) they are typed as the very first keystroke(s) after TECO issues its asterisk prompt. The {\tt }, {\tt }, and {\tt } commands are also described in Chapter~\ref{Basics of TECO}, where they are introduced as {\em immediate inspection commands}. \begin{table}[h] \caption{\bf{Immediate Action Commands}} \end{table} \nopagebreak \begin{list}{}{\labelsep 20pt} \item [{\em CHARACTER}] {\em EXPLANATION} \item [{\tt ?}] \index{[?] \tt ?} If the previous command aborted because of an error, this immediate action command causes TECO to print the erroneous command string from the beginning of the current macro level up to and including the character that caused the error. \item [{\tt /}] \index{[/] \tt /} If TECO has just printed an error message, type this immediate action command to receive a more detailed explanation of the error. (On VAX/VMS, a HELP command is also available. See section \ref{Help}.) {\em [In TECO-11, implemented only on VAX/VMS]} \ifnotintecoten \item [{\tt }] \index{[LF] \fbox{LF}} Typing this immediate action command, line feed, as the first keystroke after TECO's prompt causes TECO to immediately execute an {\tt LT} command. This aid lets you ``walk through'' a file on a non-scope terminal. (If the {\tt EV} flag is non-zero, then the {\tt T} portion of this command is redundant and therefore is not performed.) If you are already positioned at the end of the text buffer, TECO-11 will not type out anything. {\em [Not in TECO-10]} \fi \iftecoelevenonly \item [{\tt }] Typing this immediate action command, {\tt }, is synonymous with typing the {\tt } immediate action command (described above). This command is available on TECOs offering the ESCAPE surrogate. {\em [TECO-11 only]} \fi \ifnotintecoten \item [{\tt }] \index{[BS] \fbox{BS}} Typing this immediate action command, backspace, (as the first keystroke after TECO's prompt) causes TECO to immediately execute a {\tt -LT} command. (If the {\tt EV} flag is non-zero, then the {\tt T} portion of this command is redundant and therefore is not performed.) {\em [Not in TECO-10]} \fi \iftecoelevenonly \item [\caret {\tt W}] \index{[CTRL/W] \fbox{CTRL/W}} Typing this immediate action command, {\tt }, as the first keystroke after TECO's prompt when split-screen scrolling is active causes TECO to re-paint the buffer display portion of the screen. (Split-screen scrolling is active when {\tt 7:W} is non-zero.) This command is useful if the display has been ``confused'' by characters from a broadcast message or type-ahead. It is also useful in conjunction with {\tt ED}'s 128 bit (which inhibits all automatic scroll display updating). {\em [TECO-11 only]} \fi \item [{\tt *q}] \index{[*] \fbox{*}} When an asterisk followed immediately by a Q-register name (any alphanumeric character, here represented by q) is the first keystroke after TECO's prompt, TECO places the previous command string into Q-register q. [In TECO-8, only the {\tt *Z} command is permitted, and TECO will automatically type the {\tt Z}.] Note that since {\tt *q} is itself an immediate action command, it may not be edited with other immediate action commands. In other words, you can't use DELETE to delete an incorrectly typed {\tt *}. {\em [In TECO-10, {\tt *q} must be followed by} {\tt }{\em .]} \end{list} \section{Introduction to Macros} \label{Introduction to Macros} \index{Macros} One of TECO's powerful features is the ability to execute ASCII text stored in a Q-register as a command string. This is called the {\em macro} facility, and a command string so stored and executed is called a {\em macro}. A Q-register may be loaded with a macro by any of several means: directly from the console (via the \caret {\tt Uq} command), by extraction from the text buffer (via the {\tt X} command), or by these or other Q-register loading commands contained in an indirect file or even in another macro. Particularly handy is the {\tt *} immediate action command, discussed in a preceding section. When you type this command as the first character following TECO's asterisk prompt, whatever immediately preceding command you just typed at the console is saved in a Q-register. You can then use that command again (and repeatedly) by using the {\tt Mq} command. You invoke a macro by using the {\tt Mq} command, where {\tt q} is the name of the Q-register in which the macro text has been stored. A related facility is that of immediate ESCAPE-sequence commands, which is discussed in the following section. \iftecoelevenonly \section{Immediate ESCAPE-Sequence Commands {\em [TECO-11 only]}} \label{Immediate ESCAPE-Sequence Commands} Certain keys on many newer terminals generate ESCape sequences. TECO provides a facility by which you can cause the pressing of one of these keys at the prompting asterisk to be interpreted as an immediate command. When this facility is enabled, a key such as one of the cursor control keys can cause TECO to immediately execute commands (previously stored as a macro). The single keystroke suffices; no {\tt } is needed. The 32 bit in the {\tt ED} flag enables immedate ESCape-sequence commands. When {\tt ED}'s 32 bit is non-zero, and the first character TECO receives after its {\tt *} prompt is ESCape, TECO will automatically read further characters and attempt to decode an ESCape sequence. The decoded ESCape sequence is resolved into a pair of numeric values, which are then passed to the macro residing in global Q-register {\tt A}. The two numeric values are a type code and a value code. They are passed to the macro in QA by an effective {\tt ,MA} \escape \escape. The macro in QA can retrieve them by code such as: \smallskip \begin{verbatim} UA ! Save the code in QA ! @O!T0,T1,T2,T3! ! Dispatch on code ! !T0! ! Type 0 codes come here ! QA@O!V0,V1,V2... \end{verbatim} The {\tt } and {\tt } codes are as follows. \begin{list}{}{\labelsep 30pt} \item [Type 0 -] \caret followed by a control character The {\tt } code is the control character's code (0 - 31.) \item [Type 1 - ] \caret followed by a letter (e.g., {\tt \caret A}), -or- \caret followed by [ then a letter (e.g., {\tt \caret [ A}), -or- CSI followed by a letter (e.g., {\tt CSI A}), -or- \caret, O, then an uppercase letter (e.g., {\tt \caret O A}) \medskip The {\tt } code is the letter's ASCII value, trimmed to 5 bits (that is, a value of 0 through 31) \end{list} \centerline{Common keys of {\tt } 1 are:} \medskip \begin {tabular}{lll} Up arrow & {\tt } 1 & {\tt } 1 \\ Down arrow & {\tt } 1 & {\tt } 2 \\ Left arrow & {\tt } 1 & {\tt } 4 \\ Right arrow & {\tt } 1 & {\tt } 3 \\ PF1 & {\tt } 1 & {\tt } 16 \\ PF2 & {\tt } 1 & {\tt } 17 \\ PF3 & {\tt } 1 & {\tt } 18 \\ PF4 & {\tt } 1 & {\tt } 19 \\ ENTER & {\tt } 1 & {\tt } 13 \\ \end{tabular} \begin{list}{}{\labelsep 30pt} \item [Type 2] - \caret followed by {\tt ?} then a letter (e.g., \caret {\tt ? p}), -or- \caret, {\tt O}, then an lowercase letter (e.g., \caret O p) \end{list} The {\tt } code is the letter's ASCII value, trimmed to 5 bits (that is, a value of 0 through 31) \centerline{Common keys of {\tt } 2 are:} \begin{tabular}{lll} Keypad , & {\tt } 2 & {\tt } 12 \\ Keypad - & {\tt } 2 & {\tt } 13 \\ Keypad . & {\tt } 2 & {\tt } 14 \\ Keypad 0 & {\tt } 2 & {\tt } 16 \\ Keypad 1 & {\tt } 2 & {\tt } 17 \\ Keypad 2 & {\tt } 2 & {\tt } 18 \\ Keypad 3 & {\tt } 2 & {\tt } 19 \\ Keypad 4 & {\tt } 2 & {\tt } 20 \\ Keypad 5 & {\tt } 2 & {\tt } 21 \\ Keypad 6 & {\tt } 2 & {\tt } 22 \\ Keypad 7 & {\tt } 2 & {\tt } 23 \\ Keypad 8 & {\tt } 2 & {\tt } 24 \\ Keypad 9 & {\tt } 2 & {\tt } 25 \\ \end{tabular} \begin{list}{}{\labelsep 30pt} \item [Type 3] - \caret followed by [ then a digit string then \squiggle -or- \item[] CSI followed by a digit string then \squiggle \medskip The {\tt } code is the value of the digit string. All of the LK201 keyboard's editing and function keys generate sequences of this format. \end{list} \fi \section{Operating System Character Filters} \label{Operating System Character Filters} In general, TECO accepts any ASCII character, whether encountered in a macro, read from an indirect file, or entered directly via a command string from the terminal. (Note that TECOs other than TECO-11 strip the eighth bit on command input.) In addition, some operating systems filter out certain characters typed at a terminal and do not pass them to TECO. So that you can be aware of the possible difficulty of entering these characters directly into a TECO command string, we list them below in Table \ref{Operating System Character Filters}. Note that these characters are still valid characters to TECO, but may have to be entered indirectly, such as by using the {\tt nI} \escape command. \medskip \begin{minipage}[t]{4.5in} \centerline{\caret {\tt T} Note} \smallskip On some operating systems, the \caret {\tt T} character is an immediate action command (to the operating system), and invokes a one-line status report. Where reference is made below in Table \ref{Operating System Character Filters} to this note, TECO causes the operating system's recognition of \caret {\tt T} to be turned off if TECO ever asks the user for input. The original state of \caret {\tt T} handling is restored upon exit. MUNGed TECO macros that never ask the user for input do not affect the operating system's handling of \caret {\tt T}. \end{minipage} \begin{table}[h] \caption{\bf{Operating System Character Filters}} \label{Operating System Character Filters} \end{table} \nopagebreak \begin{tabular}{lll} SYSTEM & CHARACTER & SYSTEM's USE \\ \medskip \nopagebreak % \if\rteleventrue RT-11 & \caret {\tt A} & VT11 support [only if GT ON] \\ & \caret {\tt B} & Background control [F/B systems only] \\ & \caret {\tt E} & VT11 support [only if GT ON] \\ & \caret {\tt F} & Foreground control [F/B systems only] \\ & \caret {\tt O} & Output control \\ & \caret {\tt Q} & Terminal Synchronization \\ & \caret {\tt S} & Terminal Synchronization \\ % \fi % \if\rstsetrue RSTS/E & \caret {\tt O} & Output control \\ & \caret {\tt Q} & Terminal Synchronization \\ & \caret {\tt S} & Terminal Synchronization \\ % \fi % \if\vmstrue VAX/VMS & \caret {\tt O} & Output control \\ & \caret {\tt Q} & Terminal Synchronization \\ & \caret {\tt S} & Terminal Synchronization \\ & \caret {\tt T} & System status (see \caret T Note above) \\ & \caret {\tt X} & Cancel Type-ahead \\ & \caret {\tt Y} & Process Interruption \\ % \fi % \if\rsxeleventrue RSX-11 & \caret {\tt O} & Output control \\ & \caret {\tt Q} & Terminal synchronization \\ & \caret {\tt S} & Terminal synchronization \\ & \caret {\tt X} & Task control [RSX-11D only] \\ % \fi % \if\tecotentrue TOPS-10 & \caret {\tt C} \caret {\tt C} & Job interruption \\ & \caret {\tt O} & Output control \\ & \caret {\tt Q} & Terminal synchronization \\ & \caret {\tt S} & Terminal synchronization \\ & \caret {\tt T} & System status \\ TOPS-20 & \caret {\tt C} \caret {\tt C} & Job interruption \\ & \caret {\tt O} & Output control \\ & \caret {\tt Q} & Terminal synchronization \\ & \caret {\tt S} & Terminal synchronization \\ & \caret {\tt T} & System status \\ % \fi % \if\tecoeighttrue OS/8 & \caret {\tt B} & Background control [F/B systems only] \\ & \caret {\tt F} & Foreground control [F/B systems only] \\ & \caret {\tt Y} & Reboot indicator [F/B systems only] \\ % \fi \end{tabular}