Does Ex mode have any practical use?

Question

Vim has an Ex mode that can be entered by entering Q, and a command line mode that can be entered with q:. A common complaint amongst new vim users is that they enter these modes accidentally when trying to quit vim. As such, I disable these keys in my ~/.vimrc to stop myself hitting them accidentally (particularly q:):

map q: <Nop>
nnoremap Q <nop>

Although I've read the vim documentation on Ex, am a moderately experienced Vim user, and understand the basic idea behind it, I still struggle to find any use for it in my daily vim use. In general it seems less useful than just entering a standard vim command-line command prefixed with :, as changes are not echoed straight away.

Does Ex have any practical everyday use in modern Vim? Is there anything that's easier to do in Ex mode than with standard commands? What is the difference between command line mode and ex mode?

Answer 1

Q is, as you found, ex mode. It's not entirely useful to use interactively, but it exists because Vim can be used to emulate the old ex binary. In fact, many systems provide the ex command by simply symlinking it to vim.

q:, or :<C-f>, instead provides a way to browse your command-line history and edit it like a normal buffer. This makes it easy to find a previous command you ran, edit it with normal Vim commands, and then run the modified command. The q/ and q? commands exist to provide the same functionality for the search history.

Answer 2

Vim in Ex mode is useful when:

• You're in need of editing (multiple) files non-interactively (as part of the script).
• Your connection is very slow or screen is not updated after your actions.
• Mappings and abbreviations are disabled.
• Common keys such as Escape or Control doesn't work properly.

Basically vi is the visual mode for ex therefore Vim Ex Mode is just emulation of ex (they still run the same code), so it is possible to get to the command mode of ex from within vi and vice-versa. There are actually two modes: Ex mode (vim -e) and improved Ex mode which allows for more advanced commands than the vi compatible Ex-mode (vim -E). See: What is the difference between Ex mode and improved Ex mode?

Ex is the root of a family of editors: edit, ex and vi. Ex is a super‐ set of ed, with the most notable extension being a display editing facility.^ex(1)

Editing files non-interactively is the most common usage and people using it in similar way as sed and awk, however they're are more stream oriented - they only read the file forward from beginning to end (they're not designed to work with multiple lines) while vim is buffer oriented - you can move forward and backward in the file as you like which makes it so powerful.

Basically:

sed is a Stream EDitor, not a file editor.

Nevertheless, people seems to abuse it for trying to edit files and the truth is that it doesn't edit files. Secondly its options such as in-place (-i) are non-standard FreeBSD extensions and may not be available on other operating systems. So if you want to avoid unportable code, I/O overhead and bad side effects (such as destroying symlinks) you should use ex which is the standard UNIX command-based editor (along with ed)^BashFAQ.

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Other things which I find useful in Ex mode is to use it as a playground (similar to python console) where you can execute many commands in a row, working/debugging regular expressions, checking vim configuration, executing external commands or working with registers, etc.

For example:

let @d = '<td></td>'
let @r = '<tr>' . repeat(@d, 5) . '</tr>'
echo @r
let @t = '<table>' . repeat(@r, 5) . '</table>'
reg

which is more easier in Ex mode than in normal mode (where you can see only your last command).

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Practical usages

I've the following aliases in my .bash_aliases:

alias trim="ex +'bufdo!%s/\s\+$//e' -scxa"
alias retab="ex +'set ts=2' +'bufdo retab' -scxa"

^{Note: Using bufdo is not ex POSIX-compliant method (as per manual), so then you can consider using it with find instead. The ! is used to force switching the buffers without saving (otherwise warning is generated).}

The first one I'm using to trim the trailing spaces in all my source files, e.g.:

trim **/*.php

The second one converts all tabs into spaces (recursively), e.g.:

retab **/*.php

For me using retab is enough, but there are some downsides described in here. Add extra -V for increased verbosity output.

^{Note that above examples using zsh/bash4 globbing (**), so make sure your shell supports it and it's enabled.}

For more practical examples (like parsing html files), check:

• How to edit files non-interactively (e.g. in pipeline)?

• How to convert a source code file into HTML?

  E.g.

  vim -E -s -c "let g:html_no_progress=1" -c "syntax on" -c "set ft=c" -c "runtime syntax/2html.vim" -cwqa myfile.c
  

Also learn further about Ex-mode at:

• Learning the vi Editor/Vim/Modes: Ex-mode

Answer 3

I rarely use ex-mode, but when I need it I'm grateful for its existance.

I sometimes access systems via ssh over VPN, and these connections can sometimes get slow. Making the problem worse, I sometimes need to edit a file on the remote side which is, in addition to being behind ssh and VPN, is over a slow serial connection (so, 9600 baud plus a lot of network latency).

It is times like this that having visual feedback and screen updates becomes more of a hindrance because what I see is delayed (the effect is kind of like talking into a mic but with speakers far away, like in a sports stadium. One's actions become choppy and sometimes confused due to the delayed feedback).

In this case, having the changes not echoed back is a useful advantage, since I can get more done in less time when I'm not waiting for the screen to update.

When I'm done making the edits, I go back to visual mode for a one-time screen update to review my work. Then I can go back to ex-mode or save because I'm done.

Answer 4

The command-line window is useful for writing out long complicated commands. Since the command history opens as a window, you can use any vim navigation or editing command/mapping.

Say you want to edit a long substitution command that you ran once, but had made a mistake:

:%165,177s:here is a whole bunch of text I wnat to replace:here is the replacement:c

In order to change the search string, you cannot use vim motions like b in the Ex line to navigate (although I believe that there are key mappings for this navigation). Instead, most people would hit the left-arrow key a bunch of times.

A better way: hit q: to go into the command-line window, k to move up to the last command, and navigate with normal motions to the part of the command you want to change. Want to change an entire word, no problem: ciw.

Answer 5

I was told by a person with partial sight who is going blind that he is switching to ex, so that's one use of it. I myself am considerably older than vi, and I switched from ed to ex a long time ago (yes, I know, "ed is the standard editor"). The only thing I do in vi mode is %-bouncing to match parens when writing Lisp code.

Answer 6

Apart from the usages already mentioned here, ex is also a way to edit files on the linux console if that happens to be on the S/390 platform and the console happens to be line-oriented instead of screen-oriented.

Answer 7

Does Ex mode have any practical use?

Probably not. However, while entering Ex mode isn't really useful, learning Ex commands still is useful, particularly because you use ex editing commands with :g/ global commands to operate on matching lines.

Answer 8

As a vim user, I appreciate the speed of using normal mode keys to move around the text. I prefer using h and l to left arrow and right arrow so my hands do not need to move to reach those keys. When I use other computer keyboards, arrow keys move, but normal mode keys still at their expected place.

When I type :%s/oldtext/newtext/gc to make a search and replace operation, I no longer can use normal mode keys to move around this line.

I prefer typing q: and going to a command editor in normal mode to edit my command the way I edit the rest of the file.

By the way, typing q: lets me view the history of commands.

I have inoremap q; q:i in my .vimrc to use q; instead of q:

Answer 9

The original "ex" was the upgraded version of the "ed" text editor in Unix. In 2BSD a visual mode was added, and the new editor was called "vi".

If one wants to use the ex command line, he will switch to command mode with the ":" key. So in my best understanding ex is actually not there for nostalgy, it is the part to provide command mode.

You can also enter its insert mode by

 :i 

then hit "enter and type your text. Exit with ^c. Or type it all on one command line, like

 :i my multiline text \with a second line.^c