Deleting few selected characters from a file in vi/vim editor

Question

Below is the command to delete first N characters in vi:

:%s/^.\{N}//g

However, I don't understand the meaning of ^.\\{N} ; can anyone explain the meaning of each character by character ?
How to extend this command to delete in-between characters from lines ?

eg deleting 4th to 50th characters from given range of lines

Answer 1

You can match specific columns with \\%c or \\%v

Delete 4th to 50th column:

 :%s/\%4c.\{-}\(\ze\%50c\|$\)//

To only delete IFF there is a 50th column:

 :%s/\%4c.\{-}\ze\%50c//

To use virtual columns (eg handy if you use tab stops):

 :%s/\%4v.\{-}\ze\%50v//

Oh,

• .\\{-} is a non-greedy match of zero or more characters.
• \\ze is the end-of-match directive, this stops the match at column 50

Answer 2

Here is the regex part explanation

^ is the start-of-the-line anchor.

. matched any character.

N indicates the number of characters the previous token will be matched

{} is used to group the count. For example you can use it as {1, 9}

So it says, From the beginning of the line, match N characters and the rest is VIM stuff.

Answer 3

^ is the start-of-line anchor; . is the universal match, {N} repeats the previous match N times.

To delete the 4th to 50th character, use :%s/^\\(.\\{4}\\).\\{46}/\\1/g .

However, it's probably easier to use rectangular selection mode: from normal mode, move to the start location, then hit Ctrl+V and you can create a rectangular selection by moving the cursor.