ex - text editor
ex [-] [-v] [-t tag] [-r] [+lineno] name ...
Ex is the root of a family of editors: edit, ex and vi. Ex is a superset of ed, with the most notable extension being a display editing facility. Display based editing is the focus of vi.
If you have not used ed, or are a casual user, you will find that the editor edit is convenient for you. It avoids some of the complexities of ex used mostly by systems programmers and persons very familiar with ed.
If you have a CRT terminal, you may wish to use a display based editor; in this case see vi (UCB), which is a command which focuses on the display editing portion of ex.
For edit and ex see the "Ex/edit command summary - Version 2.0." The document "Edit: A tutorial" provides a comprehensive introduction to edit assuming no previous knowledge of computers or the UNIX system.
The "Ex Reference Manual - Version 2.0" is a comprehensive and complete manual for the command mode features of ex, but you cannot learn to use the editor by reading it. For an introduction to more advanced forms of editing using the command mode of ex see the editing documents written by Brian Kernighan for the editor ed; the material in the introductory and advanced documents works also with ex.
"An Introduction to Display Editing with Vi" introduces the display editor vi and provides reference material on vi. The "Vi Quick Reference" card summarizes the commands of vi in a useful, functional way, and is useful with the Introduction.
If you have used ed you will find that ex has a number of new features useful on CRT terminals. Intelligent terminals and high speed terminals are very pleasant to use with vi. Generally, the editor uses far more of the capabilities of terminals than ed does, and uses the terminal capability data base termcap (UCB) and the type of the terminal you are using from the variable TERM in the environment to determine how to drive your terminal efficiently. The editor makes use of features such as insert and delete character and line in its visual command (which can be abbreviated vi) and which is the central mode of editing when using vi (UCB). There is also an interline editing open (o) command which works on all terminals.
Ex contains a number of new features for easily viewing the text of the file. The z command gives easy access to windows of text. Hitting ^D causes the editor to scroll a half-window of text and is more useful for quickly stepping through a file than just hitting return. Of course, the screen oriented visual mode gives constant access to editing context.
Ex gives you more help when you make mistakes. The undo (u) command allows you to reverse any single change which goes astray. Ex gives you a lot of feedback, normally printing changed lines, and indicates when more than a few lines are affected by a command so that it is easy to detect when a command has affected more lines than it should have.
The editor also normally prevents overwriting existing files unless you edited them so that you don't accidentally clobber with a write a file other than the one you are editing. If the system (or editor) crashes, or you accidentally hang up the phone, you can use the editor recover command to retrieve your work. This will get you back to within a few lines of where you left off.
Ex has several features for dealing with more than one file at a time. You can give it a list of files on the command line and use the next (n) command to deal with each in turn. The next command can also be given a list of file names, or a pattern as used by the shell to specify a new set of files to be dealt with. In general, filenames in the editor may be formed with full shell metasyntax. The metacharacter `%' is also available in forming filenames and is replaced by the name of the current file. For editing large groups of related files you can use ex's tag command to quickly locate functions and other important points in any of the files. This is useful when working on a large program when you want to quickly find the definition of a particular function. The command ctags (UCB) builds a tags file or a group of C programs.
For moving text between files and within a file the editor has a group of buffers, named a through z. You can place text in these named buffers and carry it over when you edit another file.
There is a command & in ex which repeats the last substitute command. In addition there is a confirmed substitute command. You give a range of substitutions to be done and the editor interactively asks whether each substitution is desired.
You can use the substitute command in ex to systematically convert the case of letters between upper and lower case. It is possible to ignore case of letters in searches and substitutions. Ex also allows regular expressions which match words to be constructed. This is convenient, for example, in searching for the word "edit" if your document also contains the word "editor".
Ex has a set of options which you can set to tailor it to your liking. One option which is very useful is the autoindent option which allows the editor to automatically supply leading white space to align text. You can then use the ^D key as a backtab and space and tab forward to align new code easily.
Miscellaneous new useful features include an intelligent join (j) command which supplies white space between joined lines automatically, commands < and > which shift groups of lines, and the ability to filter portions of the buffer through commands such as sort.
|/etc/termcap||describes capabilities of terminals|
|~/.exrc||editor startup file|
|/tmp/Rxnnnnn||named buffer temporary|
awk(1), ed(1), grep(1), sed(1), edit(UCB), grep(UCB), termcap(UCB), vi(UCB)
The undo command causes all marks to be lost on lines changed and then restored if the marked lines were changed.
Undo never clears the buffer modified condition.
The z command prints a number of logical rather than physical lines. More than a screen full of output may result if long lines are present.
File input/output errors don't print a name if the command line `-' option is used.
There is no easy way to do a single scan ignoring case.
Because of the implementation of the arguments to next, only 512 bytes of argument list are allowed there.
The format of /etc/termcap and the large number of capabilities of terminals used by the editor cause terminal type setup to be rather slow.
The editor does not warn if text is placed in named buffers and not used before exiting the editor.
Null characters are discarded in input files, and cannot appear in resultant files.