MAINED provides a complete set of commands to manipulate files and buffers; you may want to use some of these commands from other front ends as well as from MAINED, since some of the front ends are based on editors that do not have as flexible a notion of file and buffer as MAINED, and therefore do not have all the commands that MAINED does.

10.1. Bringing a File into the Editor

When any of the commands in Table 10–1 is issued, MAINEDIT prompts for the file name s on the message line at the top of the screen. The subsequent dialogue is the same as that described for the initial file in Chapter 1 of the MAINEDIT User's Guide, except that if you type the name of a file for which a buffer already exists, MAINEDIT prompts to confirm that you want to use the existing buffer. The .B command is usually used to move into an existing buffer; the .F command is intended primarily for creating new buffers.

When any of the commands in Table 10–2 is issued, MAINEDIT prompts for the buffer name s on the message line at the top of the screen. If the buffer exists, MAINEDIT positions the cursor there; if not, MAINEDIT inquires whether you wish to create a new buffer.

If the buffer you want to edit is already visible in a window on the screen, the cursor is moved to that window and is positioned at the last place you edited in that buffer.

10.3. Modifiers of the .F and .B Commands

The dot dot modifier (..) means make all windows on the screen the same size (proportional windows). A new window is created if it is not already on the screen. If there are m windows on the screen, then the size of each window is adjusted so that the window occupies 1/mth of the screen. n is the minimum number of rows (excluding the status line) in a window (1 if n is unspecified). n is sticky, i.e., it remains in effect until changed by a subsequent ..{n}B or ..{n}F command. When a new window is created, some existing windows may be killed to ensure that all remaining windows are at least n rows. The ..{n}B and ..{n}F commands do not affect the setting of the proportionalWindowsMode option discussed in Chapter 16.

The plus dot dot (+..) or minus dot dot (-..) modifier combines the effect of the plus or minus modifier and the dot dot modifier. These are often the most useful modifiers, since by default (with no size argument) they add a new window to the screen and resize the other windows to accommodate it. For example, if you are editing three windows, and want to edit a file foo in a fourth window at the top of the screen, and also to adjust each window to occupy a quarter of the screen, you would issue the command:

-..Ffoo<eol>

When the .B commands prompt for the buffer name, they offer as a default the name of the buffer in which the cursor was located before it was moved to the current buffer, if any. For example:

Buffer (MEMO): <eol>         (to go to buffer MEMO)

Buffer (MEMO): OUTLINE<eol>  (to go to buffer OUTLINE)

The default makes it simple to bounce back and forth between two buffers.

The .B command accepts a string that is a substring of an existing buffer name, e.g., OUT or LINE would be sufficient to specify the buffer OUTLINE. If you give an answer that is a substring of more than one existing buffer name, one of the buffers is arbitrarily chosen by MAINEDIT. If the name you specify is not a substring of an existing buffer, MAINEDIT asks:

New buffer OUTLINE (Yes No)?

Type Y (or y) to create a new buffer. If you do so, a buffer containing a single blank line is created and the cursor moved to its window.

If you type N (or n) to the New buffer prompt, the original Buffer: prompt is repeated. You may wish to use the <abort> key to discontinue the dialogue if you decide you do not want to change buffers after all; see Section 13.1.

The .Y command (see Chapter 3) provides a simple means of moving among buffers that are visible on the screen.

If you specify ? as the name of a file to edit, either as part of MAINEDIT's .F command or in response to MAINEDIT's initial file prompt, MAINEDIT displays in CMDLOG the names of the files you've recently edited, one per line, most recently edited first, and place the cursor at the start of the first line it displays. You can use this feature if you want to edit a file that you have recently edited (i.e., it is still in the editor's context), but it is not the most recently edited file, and you do not want to retype its name. Once the editor displays the names of the files in its context, you can edit any file in the list without actually having to type its name by moving the cursor to the line containing the file to be edited, typing .DL (to save the file name in the editor's line delete buffer), typing .F (or whatever command you want to use to edit a file), and responding to the editor's File: prompt with <ecm> (to recover the file name from the line delete buffer).

Similarly, if you specify ? as the buffer name as part of MAINEDIT's .B command, MAINEDIT displays the names of its buffers in CMDLOG, one per line, most recently edited first, and places the cursor at the start of the first line it displays.

10.4. Deleting Buffers

Kill buffer MEMO (Yes No)?

Type Y (or y) to delete the buffer, N (or n) to retain it. If you delete a buffer that has been changed since it was last saved, MAINEDIT prompts:

Write buffer MEMO (Yes No)?

Type Y (or y) to save the text in this buffer on a file (if you do not do so, your changes to the buffer are lost). When a buffer in a window on the screen is deleted, it disappears from the screen. If the current buffer is killed, MAINEDIT prompts for a new buffer to which to move the cursor (unless all the buffers have been killed, in which case it prompts for a file to edit).

The form Q.K is used to kill just one buffer. This command prompts for the name of the buffer to kill, the default being the current buffer.

10.5. Changing Buffer and File Names

MAINED prompts for s on the message line. For Q.B, MAINED offers the file name associated with the current buffer, converted to upper case, as the default buffer name. Type the new buffer name, or just <eol> to accept the default:

New buffer name (BAR): FOO<eol>
    (to change the current buffer's name to FOO)

New buffer name (BAR): <eol>
    (to change the current buffer's name to BAR)

The file name associated with a buffer is the default name of the file into which the text of the buffer is copied when the buffer is saved. The file name associated with a buffer is independent of the buffer name, but by default the buffer name is the same as its associated file name converted to upper case.

10.6. Displaying Information about Buffers and Files

Example 10–4 shows the format of the information displayed by the Q= command. The buffer name of each edit buffer is displayed in the BUFFER column. The FILE column shows the name of the file associated with the buffer, if any. The STATUS may contain three different characters:

• D means that the buffer is dirty (has changes that have not been saved).

• S means that the buffer has been saved during the current edit session (and hence was once dirty).

• A means that the buffer is anchored.

When the .B and .F commands are typed, the user is prompted for a buffer or file name, respectively. If the specified name is followed by a comma, then MAINEDIT prompts for the names of the front and back ends to be used for the buffer. Defaults are offered in parentheses. The currently supported back ends are DATMGR and TXTMGR.

In addition to the standard back ends, MAINEDIT recognizes the special form =foo. In this case, MAINEDIT assumes that foo is the name of a buffer (partial matches are recognized) and it shares that buffer's back end as the back end of the new buffer. This means that the new buffer shares the same data as the buffer FOO. The response =<eol> is equivalent to =foo<eol> if foo is the current buffer.

When changes are made to data shared by more than one buffer, the changes are reflected in all buffers that share the data (there is only one copy of the data). In addition, all windows in which the affected data are visible are updated. There is no limit on the number of buffers that can share the same back end.

To create a new buffer FOO2 that shares the same data as an existing buffer FOO, do:

-.B                 Create a new buffer (at top of screen)
foo2,<eol>          Call it foo2, enter subcommand mode
Y                   Yes to New buffer prompt
<eol>               Use default front end
=foo<eol>           Use foo's back end for foo2

During MAINEDIT's initial dialogue, the user is prompted for the name of a file to edit. If the last character of the response is a comma, then MAINEDIT strips off the comma and prompts for the display module. When MAINEDIT creates the initial buffer, it once again examines the last of the remaining characters. If it is a comma, MAINEDIT strips it off and prompts for the names of the front and back ends to be used for the buffer. Thus, to specify a front or back end different from the default for the initial buffer, type two commas after the file name.