I have this dataset in a csv file
1.33570301776, 3.61194e-06, 7.24503e-06, -9.91572e-06, 1.25098e-05, 0.0102828, 0.010352, 0.0102677, 0.0103789, 0.00161604, 0.00167978, 0.00159998, 0.00182596, 0.0019804, 0.0133687, 0.010329, 0.00163437, 0.00191202, 0.0134425
1.34538754675, 3.3689e-06, 9.86066e-06, -9.12075e-06, 1.18058e-05, 0.00334344, 0.00342207, 0.00332897, 0.00345504, 0.00165532, 0.00170412, 0.00164234, 0.00441903, 0.00459294, 0.00449357, 0.00339737, 0.00166596, 0.00451926, 0.00455153
1.34808186291, -1.99011e-06, 6.53026e-06, -1.18909e-05, 9.52337e-06, 0.00158065, 0.00166529, 0.0015657, 0.0017022, 0.000740644, 0.00078635, 0.000730052, 0.00219736, 0.00238191, 0.00212762, 0.00163783, 0.000750669, 0.00230171, 0.00217917
As you can see, the numbers are formatted differently and misaligned. Is there a way in vim to quickly align the columns properly, so that the result is this
1.33570301776, 3.61194e-06, 7.24503e-06, -9.91572e-06, 1.25098e-05, 0.0102828, 0.010352, 0.0102677, 0.0103789, 0.00161604, 0.00167978, 0.00159998, 0.00182596, 0.0019804, 0.0133687, 0.010329, 0.00163437, 0.00191202, 0.0134425
1.34538754675, 3.3689e-06, 9.86066e-06, -9.12075e-06, 1.18058e-05, 0.00334344, 0.00342207, 0.00332897, 0.00345504,0.00165532, 0.00170412, 0.00164234, 0.00441903, 0.00459294, 0.00449357, 0.00339737, 0.00166596, 0.00451926, 0.00455153
1.34808186291, -1.99011e-06, 6.53026e-06, -1.18909e-05, 9.52337e-06, 0.00158065, 0.00166529, 0.0015657, 0.0017022, 0.000740644,0.00078635, 0.000730052,0.00219736, 0.00238191, 0.00212762, 0.00163783, 0.000750669,0.00230171, 0.00217917
That would be great to copy and paste sections with ctrl-v. Any hints?
If you're on some kind of UNIX (Linux, etc), you can cheat and filter it through the column(1) command.
:%!column -t
The above will parse on delimiters inside string literals which is wrong, so you will likely need pre-processing steps and specifying the delimiter for this file for example:
%!sed 's/","/\&/' | column -t -s '&'
Sometimes we want to align just two columns. In that case, we don't need any plugins and can use pure Vim functionality like this:
Choose a separator. In OP's post this is a comma, in my example this is =.
Add spaces before/after it. I use s/=/= ...spaces... / in visual selection for this.
Locate to the longest word and place cursor after it.
Remove all the extra whitespace using dw and vertical movement.
Example of this technique demonstrated below:
I don't find myself needing to align things often enough to install another plugin, so this was my preferred way of accomplishing it - especially that it doesn't require much thinking.
As sunny256 suggested, the column command is a great way of doing this on Unix/Linux machines, but if you want to do it in pure Vim (so that it can be used in Windows as well), the easiest way is to install the Align plugin and then do:
:%Align ,
:%s/\(\s\+\),\s/,\1/g
The first line aligns the entries on the commas and the second moves the comma so that it's flush with the preceding value. You may be able to use AlignCtrl to define a custom mapping that does the whole lot in one go, but I can never remember how to use it...
Edit
If you don't mind two spaces between entries and you want to do this in one command, you can also do:
:%Align ,\zs
This is a great answer using vim macros: https://stackoverflow.com/a/8363786/59384 - basically, you start recording a macro, format the first column, stop recording then repeat the macro for all remaining lines.
Copy/pasted from that answer:
qa0f:w100i <Esc>19|dwjq4#a
Note the single space after the 100i, and the <Esc> means "press escape"--don't type "<Esc>" literally.
Translation:
qa -- record macro in hotkey a
0 -- go to beginning of line
f: -- go to first : symbol
w -- go to next non-space character after the symbol
100i <Esc> -- insert 100 spaces
19| -- go to 19th column (value 19 figured out manually)
dw -- delete spaces until : symbol
j -- go to next line
q -- stop recording macro
4#a -- run the macro 4 times (for the remaining 4 lines)
We now also have the fabulous EasyAlign plugin, written by junegunn.
Demonstration GIF from its README:
Also, Tabularize is quite good http://vimcasts.org/episodes/aligning-text-with-tabular-vim/
You could use the csv.vim plugin.
:%ArrangeColumn
However, this will not do exactly what you have asked: it will right adjust the contents of cells, whereas you have your values aligned by the decimal point or by the first digit.
The plugin has many other useful commands for working with CSV files.
also if you have very long columns it can be handy to disable default wrapping
:set nowrap
:%!column -t
(note in debian you also have a further option for column -n which if you want to split multiple adjacent delimiters)
Here’s a pure Vim script answer, no plugins, no macros:
It might be most clear to start out with my problem’s solution as an example. I selected the lines of code I wanted to affect, then used the following command (recall that entering command mode from visual mode automatically prepends the “'<,'>”, so it acts on the visual range):
:'<,'>g``normal / "value<0d>D70|P`
Except I did NOT actually type “<0d>”. You can enter unprintable characters on the command line by pressing ctrl-v, then the key you want to type. “<0d>” is what is rendered on the command line after I typed ‘ctrl-v enter’. Here, it’s parsed by the “normal” command as the exit from “/” search mode. The cursor then jumps to “ value” in the current line.
Then we simply [D]elete the rest of the line, jump to column 70 (or whatever you need in your case), and [P]ut what we just deleted. This does mean we have to determine the width of the widest line, up to our search. If you haven’t put that information in your statusline, you can see the column of the cursor by entering the normal mode command ‘g ctrl-g’. Also note that jumping to a column that doesn’t exist requires the setting 'virtualedit'!
I left the search term for the :g(lobal) command empty, since we used a visual block and wanted to affect every line, but you can leave off using a visual selection (and the “'<,'>”) and put a search term there instead. Or combine a visual selection and a search term to narrow things more finely/easily.
Here’s something I learned recently: if you mess up on a complex command mode command, undo with ‘u’ (if it affected the buffer), then press “q:” to enter a special command history buffer that acts much like a conventional buffer. Edit any line and press enter, and the changed command is entered as a new command. Indispensable if you don’t want to have to stress over formulating everything perfectly the first time.
I just wrote tablign for this purpose. Install with
pip3 install tablign --user
Then simply mark the table in vim and do
:'<,'>:!tablign
Pretty old question, but I've recently availed myself of an excellent vim plugin that enables table formatting either on the fly or after-the-fact (as your use case requires):
https://github.com/dhruvasagar/vim-table-mode
I have this in my .vimrc.
command! CSV set nowrap | %s/,/,|/g | %!column -n -t -s "|"
This aligns the columns while keeping the comma, which may be needed later for correct reading. For example, with Python Pandas read_csv(..., skipinitialspace=True), thanks Pandas guys for this smart option, otherwise in vim %s/,\s\+/,/g. It may be easier if your column has the option --output-separator I guess, my doesn't and I'm not sure why (my man page for column says 2004, on ubuntu 18.04, not sure ubuntu will get a new version). Anyway, this works for me, and comment if you have any suggestions.
I made a cli tool written in Perl.
You can find it here: https://github.com/bas080/colcise
Locked. This question and its answers are locked because the question is off-topic but has historical significance. It is not currently accepting new answers or interactions.
I've heard a lot about Vim, both pros and cons.
It really seems you should be (as a developer) faster with Vim than with any other editor.
I'm using Vim to do some basic stuff and I'm at best 10 times less productive with Vim.
The only two things you should care about when you talk about speed (you may not care enough about them, but you should) are:
Using alternatively left and right
hands is the fastest way to use the
keyboard.
Never touching the mouse is the
second way to be as fast as possible.
It takes ages for you to move your hand,
grab the mouse, move it, and bring it
back to the keyboard (and you often have
to look at the keyboard to be sure you
returned your hand properly to the right place)
Here are two examples demonstrating why I'm far less productive with Vim.
Copy/Cut & paste. I do it all the time. With all the contemporary editors you press Shift with the left hand, and you move the cursor with your right hand to select text. Then Ctrl+C copies, you move the cursor and Ctrl+V pastes.
With Vim it's horrible:
yy to copy one line (you almost never want the whole line!)
[number xx]yy to copy xx lines into the buffer. But you never know exactly if you've selected what you wanted. I often have to do [number xx]dd then u to undo!
Another example? Search & replace.
In PSPad: Ctrl+f then type what you want you search for, then press Enter.
In Vim: /, then type what you want to search for, then if there are some special characters put \ before each special character, then press Enter.
And everything with Vim is like that: it seems I don't know how to handle it the right way.
NB : I've already read the Vim cheat sheet :)
My question is:
What is the way you use Vim that makes you more productive than with a contemporary editor?
Your problem with Vim is that you don't grok vi.
You mention cutting with yy and complain that you almost never want to cut whole lines. In fact programmers, editing source code, very often want to work on whole lines, ranges of lines and blocks of code. However, yy is only one of many way to yank text into the anonymous copy buffer (or "register" as it's called in vi).
The "Zen" of vi is that you're speaking a language. The initial y is a verb. The statement yy is a synonym for y_. The y is doubled up to make it easier to type, since it is such a common operation.
This can also be expressed as dd P (delete the current line and paste a copy back into place; leaving a copy in the anonymous register as a side effect). The y and d "verbs" take any movement as their "subject." Thus yW is "yank from here (the cursor) to the end of the current/next (big) word" and y'a is "yank from here to the line containing the mark named 'a'."
If you only understand basic up, down, left, and right cursor movements then vi will be no more productive than a copy of "notepad" for you. (Okay, you'll still have syntax highlighting and the ability to handle files larger than a piddling ~45KB or so; but work with me here).
vi has 26 "marks" and 26 "registers." A mark is set to any cursor location using the m command. Each mark is designated by a single lower case letter. Thus ma sets the 'a' mark to the current location, and mz sets the 'z' mark. You can move to the line containing a mark using the ' (single quote) command. Thus 'a moves to the beginning of the line containing the 'a' mark. You can move to the precise location of any mark using the ` (backquote) command. Thus `z will move directly to the exact location of the 'z' mark.
Because these are "movements" they can also be used as subjects for other "statements."
So, one way to cut an arbitrary selection of text would be to drop a mark (I usually use 'a' as my "first" mark, 'z' as my next mark, 'b' as another, and 'e' as yet another (I don't recall ever having interactively used more than four marks in 15 years of using vi; one creates one's own conventions regarding how marks and registers are used by macros that don't disturb one's interactive context). Then we go to the other end of our desired text; we can start at either end, it doesn't matter. Then we can simply use d`a to cut or y`a to copy. Thus the whole process has a 5 keystrokes overhead (six if we started in "insert" mode and needed to Esc out command mode). Once we've cut or copied then pasting in a copy is a single keystroke: p.
I say that this is one way to cut or copy text. However, it is only one of many. Frequently we can more succinctly describe the range of text without moving our cursor around and dropping a mark. For example if I'm in a paragraph of text I can use { and } movements to the beginning or end of the paragraph respectively. So, to move a paragraph of text I cut it using { d} (3 keystrokes). (If I happen to already be on the first or last line of the paragraph I can then simply use d} or d{ respectively.
The notion of "paragraph" defaults to something which is usually intuitively reasonable. Thus it often works for code as well as prose.
Frequently we know some pattern (regular expression) that marks one end or the other of the text in which we're interested. Searching forwards or backwards are movements in vi. Thus they can also be used as "subjects" in our "statements." So I can use d/foo to cut from the current line to the next line containing the string "foo" and y?bar to copy from the current line to the most recent (previous) line containing "bar." If I don't want whole lines I can still use the search movements (as statements of their own), drop my mark(s) and use the `x commands as described previously.
In addition to "verbs" and "subjects" vi also has "objects" (in the grammatical sense of the term). So far I've only described the use of the anonymous register. However, I can use any of the 26 "named" registers by prefixing the "object" reference with " (the double quote modifier). Thus if I use "add I'm cutting the current line into the 'a' register and if I use "by/foo then I'm yanking a copy of the text from here to the next line containing "foo" into the 'b' register. To paste from a register I simply prefix the paste with the same modifier sequence: "ap pastes a copy of the 'a' register's contents into the text after the cursor and "bP pastes a copy from 'b' to before the current line.
This notion of "prefixes" also adds the analogs of grammatical "adjectives" and "adverbs' to our text manipulation "language." Most commands (verbs) and movement (verbs or objects, depending on context) can also take numeric prefixes. Thus 3J means "join the next three lines" and d5} means "delete from the current line through the end of the fifth paragraph down from here."
This is all intermediate level vi. None of it is Vim specific and there are far more advanced tricks in vi if you're ready to learn them. If you were to master just these intermediate concepts then you'd probably find that you rarely need to write any macros because the text manipulation language is sufficiently concise and expressive to do most things easily enough using the editor's "native" language.
A sampling of more advanced tricks:
There are a number of : commands, most notably the :% s/foo/bar/g global substitution technique. (That's not advanced but other : commands can be). The whole : set of commands was historically inherited by vi's previous incarnations as the ed (line editor) and later the ex (extended line editor) utilities. In fact vi is so named because it's the visual interface to ex.
: commands normally operate over lines of text. ed and ex were written in an era when terminal screens were uncommon and many terminals were "teletype" (TTY) devices. So it was common to work from printed copies of the text, using commands through an extremely terse interface (common connection speeds were 110 baud, or, roughly, 11 characters per second -- which is slower than a fast typist; lags were common on multi-user interactive sessions; additionally there was often some motivation to conserve paper).
So the syntax of most : commands includes an address or range of addresses (line number) followed by a command. Naturally one could use literal line numbers: :127,215 s/foo/bar to change the first occurrence of "foo" into "bar" on each line between 127 and 215. One could also use some abbreviations such as . or $ for current and last lines respectively. One could also use relative prefixes + and - to refer to offsets after or before the curent line, respectively. Thus: :.,$j meaning "from the current line to the last line, join them all into one line". :% is synonymous with :1,$ (all the lines).
The :... g and :... v commands bear some explanation as they are incredibly powerful. :... g is a prefix for "globally" applying a subsequent command to all lines which match a pattern (regular expression) while :... v applies such a command to all lines which do NOT match the given pattern ("v" from "conVerse"). As with other ex commands these can be prefixed by addressing/range references. Thus :.,+21g/foo/d means "delete any lines containing the string "foo" from the current one through the next 21 lines" while :.,$v/bar/d means "from here to the end of the file, delete any lines which DON'T contain the string "bar."
It's interesting that the common Unix command grep was actually inspired by this ex command (and is named after the way in which it was documented). The ex command :g/re/p (grep) was the way they documented how to "globally" "print" lines containing a "regular expression" (re). When ed and ex were used, the :p command was one of the first that anyone learned and often the first one used when editing any file. It was how you printed the current contents (usually just one page full at a time using :.,+25p or some such).
Note that :% g/.../d or (its reVerse/conVerse counterpart: :% v/.../d are the most common usage patterns. However there are couple of other ex commands which are worth remembering:
We can use m to move lines around, and j to join lines. For example if you have a list and you want to separate all the stuff matching (or conversely NOT matching some pattern) without deleting them, then you can use something like: :% g/foo/m$ ... and all the "foo" lines will have been moved to the end of the file. (Note the other tip about using the end of your file as a scratch space). This will have preserved the relative order of all the "foo" lines while having extracted them from the rest of the list. (This would be equivalent to doing something like: 1G!GGmap!Ggrep foo<ENTER>1G:1,'a g/foo'/d (copy the file to its own tail, filter the tail through grep, and delete all the stuff from the head).
To join lines usually I can find a pattern for all the lines which need to be joined to their predecessor (all the lines which start with "^ " rather than "^ * " in some bullet list, for example). For that case I'd use: :% g/^ /-1j (for every matching line, go up one line and join them). (BTW: for bullet lists trying to search for the bullet lines and join to the next doesn't work for a couple reasons ... it can join one bullet line to another, and it won't join any bullet line to all of its continuations; it'll only work pairwise on the matches).
Almost needless to mention you can use our old friend s (substitute) with the g and v (global/converse-global) commands. Usually you don't need to do so. However, consider some case where you want to perform a substitution only on lines matching some other pattern. Often you can use a complicated pattern with captures and use back references to preserve the portions of the lines that you DON'T want to change. However, it will often be easier to separate the match from the substitution: :% g/foo/s/bar/zzz/g -- for every line containing "foo" substitute all "bar" with "zzz." (Something like :% s/\(.*foo.*\)bar\(.*\)/\1zzz\2/g would only work for the cases those instances of "bar" which were PRECEDED by "foo" on the same line; it's ungainly enough already, and would have to be mangled further to catch all the cases where "bar" preceded "foo")
The point is that there are more than just p, s, and d lines in the ex command set.
The : addresses can also refer to marks. Thus you can use: :'a,'bg/foo/j to join any line containing the string foo to its subsequent line, if it lies between the lines between the 'a' and 'b' marks. (Yes, all of the preceding ex command examples can be limited to subsets of the file's lines by prefixing with these sorts of addressing expressions).
That's pretty obscure (I've only used something like that a few times in the last 15 years). However, I'll freely admit that I've often done things iteratively and interactively that could probably have been done more efficiently if I'd taken the time to think out the correct incantation.
Another very useful vi or ex command is :r to read in the contents of another file. Thus: :r foo inserts the contents of the file named "foo" at the current line.
More powerful is the :r! command. This reads the results of a command. It's the same as suspending the vi session, running a command, redirecting its output to a temporary file, resuming your vi session, and reading in the contents from the temp. file.
Even more powerful are the ! (bang) and :... ! (ex bang) commands. These also execute external commands and read the results into the current text. However, they also filter selections of our text through the command! This we can sort all the lines in our file using 1G!Gsort (G is the vi "goto" command; it defaults to going to the last line of the file, but can be prefixed by a line number, such as 1, the first line). This is equivalent to the ex variant :1,$!sort. Writers often use ! with the Unix fmt or fold utilities for reformating or "word wrapping" selections of text. A very common macro is {!}fmt (reformat the current paragraph). Programmers sometimes use it to run their code, or just portions of it, through indent or other code reformatting tools.
Using the :r! and ! commands means that any external utility or filter can be treated as an extension of our editor. I have occasionally used these with scripts that pulled data from a database, or with wget or lynx commands that pulled data off a website, or ssh commands that pulled data from remote systems.
Another useful ex command is :so (short for :source). This reads the contents of a file as a series of commands. When you start vi it normally, implicitly, performs a :source on ~/.exinitrc file (and Vim usually does this on ~/.vimrc, naturally enough). The use of this is that you can change your editor profile on the fly by simply sourcing in a new set of macros, abbreviations, and editor settings. If you're sneaky you can even use this as a trick for storing sequences of ex editing commands to apply to files on demand.
For example I have a seven line file (36 characters) which runs a file through wc, and inserts a C-style comment at the top of the file containing that word count data. I can apply that "macro" to a file by using a command like: vim +'so mymacro.ex' ./mytarget
(The + command line option to vi and Vim is normally used to start the editing session at a given line number. However it's a little known fact that one can follow the + by any valid ex command/expression, such as a "source" command as I've done here; for a simple example I have scripts which invoke: vi +'/foo/d|wq!' ~/.ssh/known_hosts to remove an entry from my SSH known hosts file non-interactively while I'm re-imaging a set of servers).
Usually it's far easier to write such "macros" using Perl, AWK, sed (which is, in fact, like grep a utility inspired by the ed command).
The # command is probably the most obscure vi command. In occasionally teaching advanced systems administration courses for close to a decade I've met very few people who've ever used it. # executes the contents of a register as if it were a vi or ex command.
Example: I often use: :r!locate ... to find some file on my system and read its name into my document. From there I delete any extraneous hits, leaving only the full path to the file I'm interested in. Rather than laboriously Tab-ing through each component of the path (or worse, if I happen to be stuck on a machine without Tab completion support in its copy of vi) I just use:
0i:r (to turn the current line into a valid :r command),
"cdd (to delete the line into the "c" register) and
#c execute that command.
That's only 10 keystrokes (and the expression "cdd #c is effectively a finger macro for me, so I can type it almost as quickly as any common six letter word).
A sobering thought
I've only scratched to surface of vi's power and none of what I've described here is even part of the "improvements" for which vim is named! All of what I've described here should work on any old copy of vi from 20 or 30 years ago.
There are people who have used considerably more of vi's power than I ever will.
You are talking about text selecting and copying, I think that you should give a look to the Vim Visual Mode.
In the visual mode, you are able to select text using Vim commands, then you can do whatever you want with the selection.
Consider the following common scenarios:
You need to select to the next matching parenthesis.
You could do:
v% if the cursor is on the starting/ending parenthesis
vib if the cursor is inside the parenthesis block
You want to select text between quotes:
vi" for double quotes
vi' for single quotes
You want to select a curly brace block (very common on C-style languages):
viB
vi{
You want to select the entire file:
ggVG
Visual block selection is another really useful feature, it allows you to select a rectangular area of text, you just have to press Ctrl-V to start it, and then select the text block you want and perform any type of operation such as yank, delete, paste, edit, etc. It's great to edit column oriented text.
Some productivity tips:
Smart movements
* and # search for the word under the cursor forward/backward.
w to the next word
W to the next space-separated word
b / e to the begin/end of the current word. (B / E for space separated only)
gg / G jump to the begin/end of the file.
% jump to the matching { .. } or ( .. ), etc..
{ / } jump to next paragraph.
'. jump back to last edited line.
g; jump back to last edited position.
Quick editing commands
I insert at the begin.
A append to end.
o / O open a new line after/before the current.
v / V / Ctrl+V visual mode (to select text!)
Shift+R replace text
C change remaining part of line.
Combining commands
Most commands accept a amount and direction, for example:
cW = change till end of word
3cW = change 3 words
BcW = to begin of full word, change full word
ciW = change inner word.
ci" = change inner between ".."
ci( = change text between ( .. )
ci< = change text between < .. > (needs set matchpairs+=<:> in vimrc)
4dd = delete 4 lines
3x = delete 3 characters.
3s = substitute 3 characters.
Useful programmer commands
r replace one character (e.g. rd replaces the current char with d).
~ changes case.
J joins two lines
Ctrl+A / Ctrl+X increments/decrements a number.
. repeat last command (a simple macro)
== fix line indent
> indent block (in visual mode)
< unindent block (in visual mode)
Macro recording
Press q[ key ] to start recording.
Then hit q to stop recording.
The macro can be played with #[ key ].
By using very specific commands and movements, VIM can replay those exact actions for the next lines. (e.g. A for append-to-end, b / e to move the cursor to the begin or end of a word respectively)
Example of well built settings
# reset to vim-defaults
if &compatible # only if not set before:
set nocompatible # use vim-defaults instead of vi-defaults (easier, more user friendly)
endif
# display settings
set background=dark # enable for dark terminals
set nowrap # dont wrap lines
set scrolloff=2 # 2 lines above/below cursor when scrolling
set number # show line numbers
set showmatch # show matching bracket (briefly jump)
set showmode # show mode in status bar (insert/replace/...)
set showcmd # show typed command in status bar
set ruler # show cursor position in status bar
set title # show file in titlebar
set wildmenu # completion with menu
set wildignore=*.o,*.obj,*.bak,*.exe,*.py[co],*.swp,*~,*.pyc,.svn
set laststatus=2 # use 2 lines for the status bar
set matchtime=2 # show matching bracket for 0.2 seconds
set matchpairs+=<:> # specially for html
# editor settings
set esckeys # map missed escape sequences (enables keypad keys)
set ignorecase # case insensitive searching
set smartcase # but become case sensitive if you type uppercase characters
set smartindent # smart auto indenting
set smarttab # smart tab handling for indenting
set magic # change the way backslashes are used in search patterns
set bs=indent,eol,start # Allow backspacing over everything in insert mode
set tabstop=4 # number of spaces a tab counts for
set shiftwidth=4 # spaces for autoindents
#set expandtab # turn a tabs into spaces
set fileformat=unix # file mode is unix
#set fileformats=unix,dos # only detect unix file format, displays that ^M with dos files
# system settings
set lazyredraw # no redraws in macros
set confirm # get a dialog when :q, :w, or :wq fails
set nobackup # no backup~ files.
set viminfo='20,\"500 # remember copy registers after quitting in the .viminfo file -- 20 jump links, regs up to 500 lines'
set hidden # remember undo after quitting
set history=50 # keep 50 lines of command history
set mouse=v # use mouse in visual mode (not normal,insert,command,help mode
# color settings (if terminal/gui supports it)
if &t_Co > 2 || has("gui_running")
syntax on # enable colors
set hlsearch # highlight search (very useful!)
set incsearch # search incremently (search while typing)
endif
# paste mode toggle (needed when using autoindent/smartindent)
map <F10> :set paste<CR>
map <F11> :set nopaste<CR>
imap <F10> <C-O>:set paste<CR>
imap <F11> <nop>
set pastetoggle=<F11>
# Use of the filetype plugins, auto completion and indentation support
filetype plugin indent on
# file type specific settings
if has("autocmd")
# For debugging
#set verbose=9
# if bash is sh.
let bash_is_sh=1
# change to directory of current file automatically
autocmd BufEnter * lcd %:p:h
# Put these in an autocmd group, so that we can delete them easily.
augroup mysettings
au FileType xslt,xml,css,html,xhtml,javascript,sh,config,c,cpp,docbook set smartindent shiftwidth=2 softtabstop=2 expandtab
au FileType tex set wrap shiftwidth=2 softtabstop=2 expandtab
# Confirm to PEP8
au FileType python set tabstop=4 softtabstop=4 expandtab shiftwidth=4 cinwords=if,elif,else,for,while,try,except,finally,def,class
augroup END
augroup perl
# reset (disable previous 'augroup perl' settings)
au!
au BufReadPre,BufNewFile
\ *.pl,*.pm
\ set formatoptions=croq smartindent shiftwidth=2 softtabstop=2 cindent cinkeys='0{,0},!^F,o,O,e' " tags=./tags,tags,~/devel/tags,~/devel/C
# formatoption:
# t - wrap text using textwidth
# c - wrap comments using textwidth (and auto insert comment leader)
# r - auto insert comment leader when pressing <return> in insert mode
# o - auto insert comment leader when pressing 'o' or 'O'.
# q - allow formatting of comments with "gq"
# a - auto formatting for paragraphs
# n - auto wrap numbered lists
#
augroup END
# Always jump to the last known cursor position.
# Don't do it when the position is invalid or when inside
# an event handler (happens when dropping a file on gvim).
autocmd BufReadPost *
\ if line("'\"") > 0 && line("'\"") <= line("$") |
\ exe "normal g`\"" |
\ endif
endif # has("autocmd")
The settings can be stored in ~/.vimrc, or system-wide in /etc/vimrc.local and then by read from the /etc/vimrc file using:
source /etc/vimrc.local
(you'll have to replace the # comment character with " to make it work in VIM, I wanted to give proper syntax highlighting here).
The commands I've listed here are pretty basic, and the main ones I use so far. They already make me quite more productive, without having to know all the fancy stuff.
The Control+R mechanism is very useful :-) In either insert mode or command mode (i.e. on the : line when typing commands), continue with a numbered or named register:
a - z the named registers
" the unnamed register, containing the text of the last delete or yank
% the current file name
# the alternate file name
* the clipboard contents (X11: primary selection)
+ the clipboard contents
/ the last search pattern
: the last command-line
. the last inserted text
- the last small (less than a line) delete
=5*5 insert 25 into text (mini-calculator)
See :help i_CTRL-R and :help c_CTRL-R for more details, and snoop around nearby for more CTRL-R goodness.
Vim Plugins
There are a lot of good answers here, and one amazing one about the zen of vi. One thing I don't see mentioned is that vim is extremely extensible via plugins. There are scripts and plugins to make it do all kinds of crazy things the original author never considered. Here are a few examples of incredibly handy vim plugins:
rails.vim
Rails.vim is a plugin written by tpope. It's an incredible tool for people doing rails development. It does magical context-sensitive things that allow you to easily jump from a method in a controller to the associated view, over to a model, and down to unit tests for that model. It has saved dozens if not hundreds of hours as a rails developer.
gist.vim
This plugin allows you to select a region of text in visual mode and type a quick command to post it to gist.github.com. This allows for easy pastebin access, which is incredibly handy if you're collaborating with someone over IRC or IM.
space.vim
This plugin provides special functionality to the spacebar. It turns the spacebar into something analogous to the period, but instead of repeating actions it repeats motions. This can be very handy for moving quickly through a file in a way you define on the fly.
surround.vim
This plugin gives you the ability to work with text that is delimited in some fashion. It gives you objects which denote things inside of parens, things inside of quotes, etc. It can come in handy for manipulating delimited text.
supertab.vim
This script brings fancy tab completion functionality to vim. The autocomplete stuff is already there in the core of vim, but this brings it to a quick tab rather than multiple different multikey shortcuts. Very handy, and incredibly fun to use. While it's not VS's intellisense, it's a great step and brings a great deal of the functionality you'd like to expect from a tab completion tool.
syntastic.vim
This tool brings external syntax checking commands into vim. I haven't used it personally, but I've heard great things about it and the concept is hard to beat. Checking syntax without having to do it manually is a great time saver and can help you catch syntactic bugs as you introduce them rather than when you finally stop to test.
fugitive.vim
Direct access to git from inside of vim. Again, I haven't used this plugin, but I can see the utility. Unfortunately I'm in a culture where svn is considered "new", so I won't likely see git at work for quite some time.
nerdtree.vim
A tree browser for vim. I started using this recently, and it's really handy. It lets you put a treeview in a vertical split and open files easily. This is great for a project with a lot of source files you frequently jump between.
FuzzyFinderTextmate.vim
This is an unmaintained plugin, but still incredibly useful. It provides the ability to open files using a "fuzzy" descriptive syntax. It means that in a sparse tree of files you need only type enough characters to disambiguate the files you're interested in from the rest of the cruft.
Conclusion
There are a lot of incredible tools available for vim. I'm sure I've only scratched the surface here, and it's well worth searching for tools applicable to your domain. The combination of traditional vi's powerful toolset, vim's improvements on it, and plugins which extend vim even further, it's one of the most powerful ways to edit text ever conceived. Vim is easily as powerful as emacs, eclipse, visual studio, and textmate.
Thanks
Thanks to duwanis for his vim configs from which I have learned much and borrowed most of the plugins listed here.
. Repeat last text-changing command
I save a lot of time with this one.
Visual mode was mentioned previously, but block visual mode has saved me a lot of time when editing fixed size columns in text file. (accessed with Ctrl-V).
gi
Go to last edited location (very useful if you performed some searching and than want go back to edit)
^P and ^N
Complete previous (^P) or next (^N) text.
^O and ^I
Go to previous (^O - "O" for old) location or to the next (^I - "I" just near to "O").
When you perform searches, edit files etc., you can navigate through these "jumps" forward and back.
I recently (got) discovered this site: http://vimcasts.org/
It's pretty new and really really good. The guy who is running the site switched from textmate to vim and hosts very good and concise casts on specific vim topics. Check it out!
CTRL + A increments the number you are standing on.
All in Normal mode:
f<char> to move to the next instance of a particular character on the current line, and ; to repeat.
F<char> to move to the previous instance of a particular character on the current line and ; to repeat.
If used intelligently, the above two can make you killer-quick moving around in a line.
* on a word to search for the next instance.
# on a word to search for the previous instance.
Session
a. save session
:mks sessionname
b. force save session
:mks! sessionname
c. load session
gvim or vim -S sessionname
Adding and Subtracting
a. Adding and Subtracting
CTRL-A ;Add [count] to the number or alphabetic character at
or after the cursor. {not in Vi
CTRL-X ;Subtract [count] from the number or alphabetic
character at or after the cursor. {not in Vi}
b. Window key unmapping
In window,
Ctrl-A already mapped for whole file selection you need to unmap in rc file.
mark mswin.vim CTRL-A mapping part as comment
or
add your rc file with unmap
c. With Macro
The CTRL-A command is very useful in a macro. Example:
Use the following steps to make a numbered list.
Create the first list entry, make sure it starts with a number.
qa - start recording into buffer 'a'
Y - yank the entry
p - put a copy of the entry below the first one
CTRL-A - increment the number
q - stop recording
#a - repeat the yank, put and increment times
Last week at work our project inherited a lot of Python code from another project. Unfortunately the code did not fit into our existing architecture - it was all done with global variables and functions, which would not work in a multi-threaded environment.
We had ~80 files that needed to be reworked to be object oriented - all the functions moved into classes, parameters changed, import statements added, etc. We had a list of about 20 types of fix that needed to be done to each file. I would estimate that doing it by hand one person could do maybe 2-4 per day.
So I did the first one by hand and then wrote a vim script to automate the changes. Most of it was a list of vim commands e.g.
" delete an un-needed function "
g/someFunction(/ d
" add wibble parameter to function foo "
%s/foo(/foo( wibble,/
" convert all function calls bar(thing) into method calls thing.bar() "
g/bar(/ normal nmaf(ldi(`aPa.
The last one deserves a bit of explanation:
g/bar(/ executes the following command on every line that contains "bar("
normal execute the following text as if it was typed in in normal mode
n goes to the next match of "bar(" (since the :g command leaves the cursor position at the start of the line)
ma saves the cursor position in mark a
f( moves forward to the next opening bracket
l moves right one character, so the cursor is now inside the brackets
di( delete all the text inside the brackets
`a go back to the position saved as mark a (i.e. the first character of "bar")
P paste the deleted text before the current cursor position
a. go into insert mode and add a "."
For a couple of more complex transformations such as generating all the import statements I embedded some python into the vim script.
After a few hours of working on it I had a script that will do at least 95% of the conversion. I just open a file in vim then run :source fixit.vim and the file is transformed in a blink of the eye.
We still have the work of changing the remaining 5% that was not worth automating and of testing the results, but by spending a day writing this script I estimate we have saved weeks of work.
Of course it would have been possible to automate this with a scripting language like Python or Ruby, but it would have taken far longer to write and would be less flexible - the last example would have been difficult since regex alone would not be able to handle nested brackets, e.g. to convert bar(foo(xxx)) to foo(xxx).bar(). Vim was perfect for the task.
Use the builtin file explorer! The command is :Explore and it allows you to navigate through your source code very very fast. I have these mapping in my .vimrc:
map <silent> <F8> :Explore<CR>
map <silent> <S-F8> :sp +Explore<CR>
The explorer allows you to make file modifications, too. I'll post some of my favorite keys, pressing <F1> will give you the full list:
-: The most useful: Change to upper directory (cd ..)
mf: Mark a file
D: Delete marked files or the file the cursor is on, if nothing ismarked.
R: Rename the file the cursor is on.
d: Create a new directory in the current directory
%: Create a new file in the current directory
I am a member of the American Cryptogram Association. The bimonthly magazine includes over 100 cryptograms of various sorts. Roughly 15 of these are "cryptarithms" - various types of arithmetic problems with letters substituted for the digits. Two or three of these are sudokus, except with letters instead of numbers. When the grid is completed, the nine distinct letters will spell out a word or words, on some line, diagonal, spiral, etc., somewhere in the grid.
Rather than working with pencil, or typing the problems in by hand, I download the problems from the members area of their website.
When working with these sudokus, I use vi, simply because I'm using facilities that vi has that few other editors have. Mostly in converting the lettered grid into a numbered grid, because I find it easier to solve, and then the completed numbered grid back into the lettered grid to find the solution word or words.
The problem is formatted as nine groups of nine letters, with -s representing the blanks, written in two lines. The first step is to format these into nine lines of nine characters each. There's nothing special about this, just inserting eight linebreaks in the appropriate places.
The result will look like this:
T-O-----C
-E-----S-
--AT--N-L
---NASO--
---E-T---
--SPCL---
E-T--OS--
-A-----P-
S-----C-T
So, first step in converting this into numbers is to make a list of the distinct letters. First, I make a copy of the block. I position the cursor at the top of the block, then type :y}}p. : puts me in command mode, y yanks the next movement command. Since } is a move to the end of the next paragraph, y} yanks the paragraph. } then moves the cursor to the end of the paragraph, and p pastes what we had yanked just after the cursor. So y}}p creates a copy of the next paragraph, and ends up with the cursor between the two copies.
Next, I to turn one of those copies into a list of distinct letters. That command is a bit more complex:
:!}tr -cd A-Z | sed 's/\(.\)/\1\n/g' | sort -u | tr -d '\n'
: again puts me in command mode. ! indicates that the content of the next yank should be piped through a command line. } yanks the next paragraph, and the command line then uses the tr command to strip out everything except for upper-case letters, the sed command to print each letter on a single line, and the sort command to sort those lines, removing duplicates, and then tr strips out the newlines, leaving the nine distinct letters in a single line, replacing the nine lines that had made up the paragraph originally. In this case, the letters are: ACELNOPST.
Next step is to make another copy of the grid. And then to use the letters I've just identified to replace each of those letters with a digit from 1 to 9. That's simple: :!}tr ACELNOPST 0-9. The result is:
8-5-----1
-2-----7-
--08--4-3
---4075--
---2-8---
--7613---
2-8--57--
-0-----6-
7-----1-8
This can then be solved in the usual way, or entered into any sudoku solver you might prefer. The completed solution can then be converted back into letters with :!}tr 1-9 ACELNOPST.
There is power in vi that is matched by very few others. The biggest problem is that only a very few of the vi tutorial books, websites, help-files, etc., do more than barely touch the surface of what is possible.
Bulk text manipulations!
Either through macros:
Start with recording: qq
Do stuff
Stop recording: q
Repeat: #q (the first time), ## after that.
Repeat 20 times: 20##
Or through regular expressions:
Replace stuff: :%s/[fo]+/bar/g
(But be warned: if you do the latter, you'll have 2 problems :).)
I recently discovered q:. It opens the "command window" and shows your most recent ex-mode (command-mode) commands. You can move as usual within the window, and pressing <CR> executes the command. You can edit, etc. too. Priceless when you're messing around with some complex command or regex and you don't want to retype the whole thing, or if the complex thing you want to do was 3 commands back. It's almost like bash's set -o vi, but for vim itself (heh!).
See :help q: for more interesting bits for going back and forth.
I just discovered Vim's omnicompletion the other day, and while I'll admit I'm a bit hazy on what does which, I've had surprisingly good results just mashing either Ctrl + x Ctrl + u or
Ctrl + n/Ctrl +p in insert mode. It's not quite IntelliSense, but I'm still learning it.
Try it out! :help ins-completion
These are not shortcuts, but they are related:
Make capslock an additional ESC (or Ctrl)
map leader to "," (comma), with this command: let mapleader=","
They boost my productivity.
Another useful vi "shortcut" I frequently use is 'xp'. This will swap the character under the cursor with the next character.
<Ctrl> + W, V to split the screen vertically
<Ctrl> + W, W to shift between the windows
!python % [args] to run the script I am editing in this window
ZF in visual mode to fold arbitrary lines
Visual Mode
As several other people have said, visual mode is the answer to your copy/cut & paste problem. Vim gives you 'v', 'V', and C-v. Lower case 'v' in vim is essentially the same as the shift key in notepad. The nice thing is that you don't have to hold it down. You can use any movement technique to navigate efficiently to the starting (or ending) point of your selection. Then hit 'v', and use efficient movement techniques again to navigate to the other end of your selection. Then 'd' or 'y' allows you to cut or copy that selection.
The advantage vim's visual mode has over Jim Dennis's description of cut/copy/paste in vi is that you don't have to get the location exactly right. Sometimes it's more efficient to use a quick movement to get to the general vicinity of where you want to go and then refine that with other movements than to think up a more complex single movement command that gets you exactly where you want to go.
The downside to using visual mode extensively in this manner is that it can become a crutch that you use all the time which prevents you from learning new vi(m) commands that might allow you to do things more efficiently. However, if you are very proactive about learning new aspects of vi(m), then this probably won't affect you much.
I'll also re-emphasize that the visual line and visual block modes give you variations on this same theme that can be very powerful...especially the visual block mode.
On Efficient Use of the Keyboard
I also disagree with your assertion that alternating hands is the fastest way to use the keyboard. It has an element of truth in it. Speaking very generally, repeated use of the same thing is slow. This most significant example of this principle is that consecutive keystrokes typed with the same finger are very slow. Your assertion probably stems from the natural tendency to use the s/finger/hand/ transformation on this pattern. To some extent it's correct, but at the extremely high end of the efficiency spectrum it's incorrect.
Just ask any pianist. Ask them whether it's faster to play a succession of a few notes alternating hands or using consecutive fingers of a single hand in sequence. The fastest way to type 4 keystrokes is not to alternate hands, but to type them with 4 fingers of the same hand in either ascending or descending order (call this a "run"). This should be self-evident once you've considered this possibility.
The more difficult problem is optimizing for this. It's pretty easy to optimize for absolute distance on the keyboard. Vim does that. It's much harder to optimize at the "run" level, but vi(m) with it's modal editing gives you a better chance at being able to do it than any non-modal approach (ahem, emacs) ever could.
On Emacs
Lest the emacs zealots completely disregard my whole post on account of that last parenthetical comment, I feel I must describe the root of the difference between the emacs and vim religions. I've never spoken up in the editor wars and I probably won't do it again, but I've never heard anyone describe the differences this way, so here it goes. The difference is the following tradeoff:
Vim gives you unmatched raw text editing efficiency
Emacs gives you unmatched ability to customize and program the editor
The blind vim zealots will claim that vim has a scripting language. But it's an obscure, ad-hoc language that was designed to serve the editor. Emacs has Lisp! Enough said. If you don't appreciate the significance of those last two sentences or have a desire to learn enough about functional programming and Lisp to develop that appreciation, then you should use vim.
The emacs zealots will claim that emacs has viper mode, and so it is a superset of vim. But viper mode isn't standard. My understanding is that viper mode is not used by the majority of emacs users. Since it's not the default, most emacs users probably don't develop a true appreciation for the benefits of the modal paradigm.
In my opinion these differences are orthogonal. I believe the benefits of vim and emacs as I have stated them are both valid. This means that the ultimate editor doesn't exist yet. It's probably true that emacs would be the easiest platform on which to base the ultimate editor. But modal editing is not entrenched in the emacs mindset. The emacs community could move that way in the future, but that doesn't seem very likely.
So if you want raw editing efficiency, use vim. If you want the ultimate environment for scripting and programming your editor use emacs. If you want some of both with an emphasis on programmability, use emacs with viper mode (or program your own mode). If you want the best of both worlds, you're out of luck for now.
Spend 30 mins doing the vim tutorial (run vimtutor instead of vim in terminal). You will learn the basic movements, and some keystrokes, this will make you at least as productive with vim as with the text editor you used before. After that, well, read Jim Dennis' answer again :)
What is the way you use Vim that makes
you more productive than with a
contemporary editor?
Being able to execute complex, repetitive edits with very few keystrokes (often using macros). Take a look at VimGolf to witness the power of Vim!
After over ten years of almost daily usage, it's hard to imagine using any other editor.
Use \c anywhere in a search to ignore case (overriding your ignorecase or smartcase settings).
E.g. /\cfoo or /foo\c will match foo, Foo, fOO, FOO, etc.
Use \C anywhere in a search to force case matching.
E.g. /\Cfoo or /foo\C will only match foo.
I was surprised to find no one mention the t movement. I frequently use it with parameter lists in the form of dt, or yt,
Odd nobody's mentioned ctags. Download "exuberant ctags" and put it ahead of the crappy preinstalled version you already have in your search path. Cd to the root of whatever you're working on; for example the Android kernel distribution. Type "ctags -R ." to build an index of source files anywhere beneath that dir in a file named "tags". This contains all tags, nomatter the language nor where in the dir, in one file, so cross-language work is easy.
Then open vim in that folder and read :help ctags for some commands. A few I use often:
Put cursor on a method call and type CTRL-] to go to the method
definition.
Type :ta name to go to the definition of name.
Automatic indentation:
gg (go to start of document)
= (indent time!)
shift-g (go to end of document)
You'll need 'filetype plugin indent on' in your .vimrc file, and probably appropriate 'shiftwidth' and 'expandtab' settings.
You asked about productive shortcuts, but I think your real question is: Is vim worth it? The answer to this stackoverflow question is -> "Yes"
You must have noticed two things. Vim is powerful, and vim is hard to learn. Much of it's power lies in it's expandability and endless combination of commands. Don't feel overwhelmed. Go slow. One command, one plugin at a time. Don't overdo it.
All that investment you put into vim will pay back a thousand fold. You're going to be inside a text editor for many, many hours before you die. Vim will be your companion.
Multiple buffers, and in particular fast jumping between them to compare two files with :bp and :bn (properly remapped to a
single Shift + p or Shift + n)
vimdiff mode (splits in two vertical buffers, with colors to show the differences)
Area-copy with Ctrl + v
And finally, tab completion of identifiers (search for "mosh_tab_or_complete"). That's a life changer.
Agreed with the top poster - the :r! command is very useful.
Most often I use it to "paste" things:
:r!cat
**Ctrl-V to paste from the OS clipboard**
^D
This way I don't have to fiddle with :set paste.
I am using Vim to read through a lot of C and Perl code containing many single letter variable names.
It would be nice to have some command to change the name of a variable to something more meaningful while I’m in the process of reading the code, so that I could read the rest of it faster.
Is there some command in Vim which could let me do this quickly?
I don’t think regexes would work because:
the same single letter name might have different purposes in different scoping blocks; and
the same combination of letters could be part of another longer variable name, a string literal, or a comment.
Are there any known solutions?
The following is how to rename a variable which is defined in the current scope {}.
Move your cursor to the variable usage. Press gd. Which means - move cursor to the definition.
Now Press [{ - this will bring you to the scope begin.
Press V - will turn on Visual Line selection.
Press % - will jump to the opposite } thus will select the whole scope.
Press :s/ - start of the substitute command.
<C-R>/ - will insert pattern that match variable name (that name you were on before pressing gd).
/newname/gc<CR> - will initiate search and replace with confirmation on every match.
Now you have to record a macros or even better - map a key.
Here are the final mappings:
" For local replace
nnoremap gr gd[{V%::s/<C-R>///gc<left><left><left>
" For global replace
nnoremap gR gD:%s/<C-R>///gc<left><left><left>
Put this to your .vimrc or just execute.
After this pressing gr on the local variable will bring you to :s command where you simply should enter new_variable_name and press Enter.
I know it's an old question, and #mykola-golubyev's way obviously IS the best answer for the particular case in the OP question (which, I assume is going through obfuscated code where you're likely to have multiple blocks with same var names); but with the question name like that many people coming here from google searches probably look for less situation-specific ways to rename variables in VIM -- and those can be more concise
I'm surprised no one suggested this way:
* :s// NEWNAME /gc
The * is the same as gn - search the next occurrence of the word under the cursor AND make it the last searched pattern; you can then omit the search pattern in the substitute command and VIM will assume that last one is the pattern to search for.
For small amounts of var copies, here's an even quicker one:
* cw NEWNAME <esc> then repeat n. for other occurrences
* is search for occurrences, cw is change word, n goes to the next occurrence of the last searched term and . repeats the last command (which is now change word to NEWNAME)
(Credits for me knowing all this go to #doomedbunnies on Reddit)
Another cool trick: (credits to #nobe4)
* cgn NEWNAME <esc> then repeat . for other occurrences
cgn is "change whatever is the result of (find next occurrence)". Now that this is the last command, you don't need the n to go to the next occurrence, so fewer strokes again, and, more importantly, no need to alternate n and .. But, obviously, this one has the drawback of not having a way to skip an occurrence.
Here are some benefits of these over other similar approaches, or language-specific plugins with refactoring support:
no command mapping, no fiddling with .vimrc(or init.vim), so you can use it in any VIM copy you come across (e.g. a quick task on some VPS or your friend's machine where configuring VIM your way would defeat the purpose of 'quick')
using * or gn for word selection is very quick -- just one keystroke (well, let's say 1.5)
using * or gn makes sure you don't get any matches inside other words, just as :%s/<C-R>//gc does. Beats typing the :%s/\<OLDNAME\>/NEWNAME/gc by hand: I personally tend to forget to use the \< things to limit matches to whole words only.
Not using a scope will only result in a few extra strokes of n to skip unwanted matches -- probably even fewer than the extra strokes needed to limit the scope to a certain code block. Under normal circumstances, your variables are most likely somewhat localised to a certain code block anyway.
AFAIK, there is no actual refactoring support in VIM. When doing a rename with the intent of a refactor I usually take the following precautions:
Limit the scope of the change my using marks.
When entering the regex, bracket the name with \< and >. This will make it match an entire word which reduces the types of incorrect renames that will occur.
Don't do a multiline replace to reduce chances of a bad replace
Look through the code diff carefully if it's anything other than a small change.
My end change looks something like this
:'a,'bs/\<foo\>/bar
I would love to be wrong about there not being a refactoring tool for VIM but I haven't seen it.
Put this in your .vimrc
" Function to rename the variable under the cursor
function! Rnvar()
let word_to_replace = expand("<cword>")
let replacement = input("new name: ")
execute '%s/\(\W\)' . word_to_replace . '\(\W\)/\1' . replacement . '\2/gc'
endfunction
Call it with :call Rnvar()
expand("<cword>") gets the word under the cursor. The search string uses % for file-scope, and the \(\W\) patterns look for non-word characters at the boundary of the word to replace, and save them in variables \1 and \2 so as to be re-inserted in the replacement pattern.
You could use the 'c' modifier in the global search and replace that would ask you for confirmation for each replace. It would take longer but it might work for a non-humongous code file:
%s/\$var/\$foo/gc
The c stands for confirm.
In c, you may be able to make some progress using cscope. It makes an attempt at understanding syntax, so would have a chance of knowing when the letter was a variable.
If this is across multiple files, you may consider taking a look at sed. Use find to grab your files and xargs plus sed for a replace. Say you want to replace a with a_better_name in all files matching *.c, you could do
find . -name "*.c" | xargs sed -i -e 's/a/a_better_name/g'
Bear in mind that this will replace ALL occurrences of a, so you may want a more robust regex.