searching in vim with only 1 match in a line - search

I want to search a pattern in vim such that if a pattern appears multiple times in a line then it should search that pattern only 1 times in that line and after it match next line.
Is there any way to do it?
Thanks,

/pattern you want to match/1
this tells vim to move down a line before finding the next match.

You can follow your pattern with .* which will cause the pattern to match the remainder of a line where it is found. The search for the next pattern starts after the end of the last found pattern.

Try :set nogdefault
Because:
'gdefault' *'gd'* 'nogdefault' *'nogd'*
'gdefault' 'gd' boolean (default off)
When on, the ":substitute" flag 'g' is default on. This means that all matches in a line are substituted instead of one. When a 'g' flag is given to a ":substitute" command, this will toggle the substitution of all or one match.

Related

I need to replace the second occurrence of string1 by string2 on every line - vim

I know that there are multiple occurrences of string1 in every line of the file. I am looking for the shortest/quickest way to replace the second one by string2. Any method will do though vim is my preference.
You can find the second occurrence of "string1" using \zs.
Based on the :h \zs example, it will be
:%s/\(.\{-}\zsstring1\)\{2}/string2
It'll be more straightforward using external sed in Vim command mode
:%!sed 's/string1/string2/2'
See https://vi.stackexchange.com/questions/8621/substitute-second-occurence-on-line for more ways to accomplish it.
Here is one way:
:%normal 0/string1^Mncgnstring2<CR>
Breakdown:
:[range]normal <macro> executes normal mode <macro> on every line in [range],
% is a shorthand for range [<first line>,<last line>], which covers every line in the buffer,
0 is the first command of our macro, it places the cursor on the first column of the line, which is a good habit to have,
/string1^M moves the cursor to the first match for string1, the ^M is a literal <CR> obtained with <C-v><CR>,
n moves the cursor to to the next match,
cgnstring2 changes the current match to string2.
See :help :range, :help :normal, :help gn.
But it would have been more interesting to see what you tried and fix it, rather than provide you with a working solution.

how to remove specific characters in vi or vim editor

I have some txt in vi:
|NC_004718|29751nt|SARS
|NC_045512|29903nt|Severe
|NC_004718|29751nt|SARS
|NC_045512|29903nt|Severe
|NC_004718|29751nt|SARS
now I want to replace remove everything after NC_004718, my expected output is:
NC_004718
NC_045512
NC_004718
NC_045512
NC_004718
How to do it? Thanks.
I would recommend using a substitution with regular expression to match the entire string and to capture what you would like to keep in parentheses. That way you can then replace the entire string with just the match.
:%s/^|\([^|]\+\)|.\+/\1/
To break down what is happening:
% means that you want to apply the command to each line within the file.
s means that you are doing substitution command (on each line). The s command has a syntax of s/<regular expression pattern>/<replacement>/<flags>
The regular eression pattern in the above command is ^|\([^|]\+\)|.\+.
^ means match from the line start.
| matches the character |.
\([^|]\+\) matches all characters except for the character |. Note that the real regular expression is actually ([^|]+), the additional \ characters are there because Vim needs to know that they are intended to be special characters for processing and not exact characters it needs to match. Also note that the parentheses are there to capture the match into a group (see below).
| again matches the actual character |.
.\+ matches all characters until the end of the line. Note that the . is considered special character by default but + still needs a preceding \.
The replacement text is only \1. This denotes that Vim should replace the text with whatever was captured in the first group (i.e. the first set of parentheses).
There are no flags with this command so there is nothing after the last /.
For example,
:g/NC_\d\+/normal! ygnV]p
:g/regex/ to match lines
normal! to execute Normal mode commands
ygn to yank the text previously matched by :g
V to select the whole line
]p or p to replace the line with the match
If you have only lines like those you have shown try:
:%norm xf|D

Can not find the good syntax for a vim sustitute pattern

I have a bunch of t_ prefixed fonction names in a header file and i would like to remove this prefix from some of them.
I have ended by typing :
:s/\(\s+\)t_\([^(]+\)(/\1\2(/c
But vim complains with Pattern not found
What is wrong in my pattern ?
You forgot to put a backslash before + to give it its quantifier meaning. You can also probably simplify it using \< to match the start of a word instead of capturing spaces.
I suggest breaking the problem down, first the search:
/\v\s+\zst_\ze.*\(
Now the substitution:
:s///\c
We can reuse a search pattern simply typing an empty search on the substitution
OBS: I suppose your functions have () at the end of the line, so .*().
Another thing; \zs and \ze to match only t_, for more see: :h \zs.
If you are using neovim you can see what happens befor hitting enter, just put these lines on your init.vim:
if has("nvim")
set inccommand=nosplit
endif

How to delete the last word from each line in vim?

Please let me know, How I can remove the last word from each line using vim commands?
Before :
abcdef 123
xyz 1256
qwert 2
asdf 159
after :
abcdef
xyz
qwert
asdf
Similarly please let me know how to remove the second word from each line using vim command?
Use the following regex (in ex mode):
%s/\s*\w\+\s*$//
This tells it to find optional whitespace, followed by one or more word characters, followed by optional whitespace, followed by end of line—then replace it with nothing.
The question's been answered already, but here's what I'd more likely end up doing:
Record a macro:
qq to record a macro into register "q"
$ to go to the end of the line
daw to delete a word
q to stop recording
Then select the rest of the lines:
j to go down a line
vG to select to the end of the file
And apply the macro:
:norm #q
Some similar alternatives:
:%norm $daw
qq$dawjq (note the added j) then 999#q to replay the macro many times. (Macro execution stops at the first "error" -- in this case, you'd probably hit the bottom of the file, j would not work, and the macro would stop.)
The key for this is the :substitute command; it is very powerful (and often used in vi / Vim).
You need to come up with a regular expression pattern that matches what you want to delete. For the last word, that's whitespace (\s), one or more times \+ (or any number (*), depending on how you want to treat single-word lines), followed by word characters (\w\+), anchored to the end of the line ($). Note that word has a special meaning in Vim; you may want to use a different atom (e.g. \S). Voila:
:%s/\s\+\w\+$//
For the second word, you can make use of the special \zs and \ze atoms that assert for matches, but do not actually match: Anchored at the start (^), match a word, then start the match for a second one:
:%s/^\w\+\s\+\zs\w\+\s\+//
Soon, you'll also want to reorder things, not just remove them. For that, you need to know capturing groups: \(...\). The text matched by those can then be referred to in the replacement part. For example, to swap the first and second words:
:%s/^\(\w\+\s\+\)\(\w\+\s\+\)/\2\1/
For details, have a look at the help, especially :help :substitute and :help pattern.
To remove the second word from the start of a line, use the following:
:%s/^\(\s*\w\+\s\+\)\w\+\s*/\1/
Update
To treat special characters as part of the word, you have to use the \S (which matches all non-whitespace characters) instead of \w (which matches only word characters [0-9A-Za-z_]). Then, the command would be:
:%s/^\(\s*\S\+\s\+\)\S\+\s*/\1/

Delete all but the first instance of a line

How to delete all but the first instance of a line, which is known?
For instance, I have
LOADING CONDITION : LIGHTSHIP CONDITION
several of these spread out through the file's contents. I would like to keep only the first instance which is somewhere near the top.
Ideas anyone?
You can use the :global command combined with a range.
:0/LOADING CONDITION/+,$g//d
Explanation:
[range]g/{pat}/{cmd} run a command, {cmd}, on every line matching {pat} inside the giving line range, [range].
0/LOADING CONDITION/ starting with the first line find the pattern LOADING CONDITION
0/LOADING CONDITION/+1 start the range 1 line below the first instance
+1 can be shorted to just + because the 1 can be assumed.
,$ the end of the range will be the last line in the file which is refereed to as $
g// use the last search pattern. In this case the pattern from the range
:delete or :d for short is the ex command used to delete the lines
For more information see
:h :g
:h :d
:h range
gg (make cursor back to top)
/LOADING CONDITION : LIGHTSHIP CONDITION (enter)
n
:.,$g//d
My PatternsOnText plugin provides a command (and other related ones) that makes this very simple:
:DeleteDuplicateLinesOf /^LOADING CONDITION : LIGHTSHIP CONDITION$/

Resources