1. Unix Fundamentals - Part iii vi Editor
UNIX III
Unix Fundamentals - Part iii
vi Editor
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2. Unix Editors Unix editors are key to use creatively the computer;
Editors allow to:
create & alter text files;
format text files;
and more.
The ex family of editors consists of
ex - line editor (replaces ed)
edit - trimmed down version of ex
vi - visual editor
ed - original standard editor.
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3. Memory Buffer Files are stored in system’s hard drive;
When using an editor, a copy of the files is pulled into memory (RAM), leaving the original file undisturbed;
This copy is stored in a temporary workspace called the buffer (in memory);
Changes are made to this copy, not to the original file;
To keep the changes, one has to write (w) the buffer onto the system’s hard drive.
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4. History of vi
vi editor was developed at UC Berkeley, as part of BSD Unix;
AT&T System V made vi part of the operating system;
Before vi the standard editor was ed;
ed was a line-oriented editor. When ex came along, ed became a subset of ex;
ex allows the user to work on a full-screen mode. This mode is called visual display (vi).
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5. History of vi (cont)
When working with ex editor, there are five modes of operation:
ex command mode;
ex input mode;
vi command mode;
vi input mode; and
vi last line mode.
Using vi most likely we use vi command mode & vi input mode. Ocassionally, we will be using last line mode.
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6. vi Screen Editor
Modes of Operation:
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7. vi Screen Editor
when vi is invoked, it starts in the command mode. This means that any keyboard stroke is interpreted as a command.
in command mode we can:
delete words;
delete lines;
change a spelling error;
and more.
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8. vi Screen Editor
To change to (text) input mode, use the append command (a). This is, press [a]-key.
when in input mode, key strokes will be interpreted as text to be stored in the buffer, not as a command;
To exit the input mode, use the [Escape]-key;
To save the changes in command mode, or the text typed in input mode, we use the write command (w).
w saves the entire buffer, or a segment of it.
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9. vi Screen Editor
Modes of Operation:
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10. vi Screen Editor Basic Commands:
Cursor Position: [h], [j], [k], [l], and [Return];
(text) Input Mode: [a], [i], [o], [O];
Leave (text) Input Mode: [Esc];
Delete / Replace: [x], [dd], [r];
Undo Changes: [u], [U];
Save / Quit vi editor: [Z][Z], :[w], :[q][!], :[w][q];
Erase characters: [Delete], [Ctrl][h].
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11. vi Screen Editor Additional vi Commands:
Cursor Position including scrolling, paging, and searching: [Ctrl][d], [Ctrl][f], [Ctrl][b], [Ctrl][u], [e], [b], [G], n[G], [Ctrl][g], /patterm, [$], [0];
Commands to operate on words, lines, sentences, paragraphs: [c], [d], [y];
Abbreviations for words, lines, sentences, paragraphs: [w], [b], [e], [<], [>], [O], [$], [{], [}];
Print buffer: [p], [P];
Join lines: [J];
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12. vi Screen Editor
To invoke vi:
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13. vi Screen Editor
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14. vi Screen Editor
When calling vi, it responds by displaying on the screen the contents of the file, followed by a series of tildes (~);
vi starts in command mode;
Cursor is positioned at the beginning of file (upper left-hand corner of display);
To leave vi, type the following sequence:
[Esc][:][w][q] [Return] or [Esc][:][w] [Return]
:wq stands for write & quit;
:w stands for quit.
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16. vi Screen Editor Cursor Movement: Use the [arrow keys], or
[h]: left move, same line;
[l]: right move, same line;
[k]: cursor up one line;
[j]: cursor down one line;
[Return]: position cursor at beginning of next line
down.
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17. vi Screen Editor (text) Input Mode:
To start typing text, use any of the following commands:
[a]: appends;
[i]: insert;
[o] and [O]: open.
Press [Return] to start a new line. When typing use the [Backspace] or [Delete] keys to backup and correct mistakes.
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18. vi Screen Editor Wraparound
The length of a line on the screen may not correspond to its actual line in the editor;
A line longer than 80 characters (typically) may show on the screen as two lines, but vi recognizes it as a single line;
Solutions:
Hit [Return]-key before the eightieth character;
In command mode, type
:set wrapmargin=nn
:set wm=nn
nn is a number representing margin size.
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19. vi Screen Editor Use of the four (text) input modes:
[a]: enters whatever is typed after the cursor, pushing the rest of the line to the right;
[i]: enters whatever is typed before the cursor, pushing the rest of the line to the right;
[o]: opens a new line below the cursor & places the cursor at the beginning of the new line;
[O]: opens a new line above the cursor & places the cursor at the beginning of the new line;
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20. vi Screen Editor Deleting & Changing Text:
All these commands are made from the command mode, and vi stays in command mode after they are executed;
Use [Esc]-key if not in command mode;
[x]: erases the character under the cursor;
nn[x]: erases nn-1 characters to the right of the cursor, and the character under the cursor;
[d][d]: deletes the line where cursor is positioned;
[r]char: replaces the character under the cursor by the character char.
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21. vi Screen Editor Undoing Changes:
These commands undo what it has been just done;
[u]: undo the last change. Issue only in command mode;
if a line has been deleted using [dd], press [u] to recover the line;
if [i] is used to insert the word mush in a line, [u] will remove the word (we must return to command mode).
[U]: undo all the changes made on the current line.
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22. vi Screen Editor Exiting vi editor:
[Esc][Z][Z]: writes the contents of the buffer onto disk for permanent storage. Uses the filename that it was used to enter vi;
[Esc][:][w][q]: w stands for write. and q stands for quit. Similar to [Esc][Z][Z];
[Esc][:][q][!]: quits vi, and discards the changes made to the temporary buffer.
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23. vi Screen Editor Cursor-positioning Commands
[b]: moves the cursor to the beginning of a word;
[e]: moves the cursor to the end of a word;
[0]: (zero) moves the cursor to the beginning of the current line;
[$]: moves the cursor to the end of the current line.
Note: with [0] or [$] the cursor does not jump to the next line or above line as it does with the [b] and [e] key commands.
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24. vi Screen Editor Screen Scrolling & Paging Commands
[Ctrl][d]: scrolls or pages the cursor down, usually 12 lines at a time;
[Ctrl][f]: scrolls or pages the cursor forward, usually 24 lines at a time;
[Ctrl][u]: scrolls or pages the cursor up, usually 12 lines at a time;
[Ctrl][b]: scrolls or pages the cursor back, usually 24 lines at a time.
Note: These commands are appropriate for mid-size text files, where a few scrolls will cover the entire file length.
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25. vi Screen Editor Screen Scrolling & Paging Commands
These are commands issue while in command mode;
nn[G]: moves the cursor to line number nn;
[G]: moves the cursor to the end-of-file;
[Ctrl][g]: echoes the line number the cursor is currently on.
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26. vi Screen Editor Pattern Search Commands issued while in command mode;
/string [Return]: vi positions the cursor at the first occurrence of string string - forward search;
?string [Return]: vi positions the cursor at the first occurrence of string string - backward search;
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27. vi Screen Editor Deletion, Changes & Rearranging Text
Operator + Scope = Command;
Example: dd is operator d, and scope d.
dw is operator d, and scope w.
Operators:
[d]: delete text, and stores a copy in a temporary memory buffer;
[p]: put(s) text, recovers text from temporary memory buffer;
[y]: yanks (copies) text, and places in temporary memory buffer, for positioning elsewhere; original remains unchanged;
[c]: change operator; equivalent to delete & insert.
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28. vi Screen Editor Deletion, Changes & Rearranging Text Scope:
[e]: from cursor position to end-of-current-word;
[w]: from cursor position to beginning of next word;
[b]: from the cursor position backwards to beginning of current word;
[$]: from the cursor position to end-of-current-line;
[0]: from cursor position to beginning-of-current-line;
[)]: from cursor position to beginning of next-sentence;
[(]: from cursor position back to beginning of current-sentence;
[}]: from cursor position to beginning of next-paragraph;
[{]: from cursor position back to beginning of current-paragraph;
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