Uncommenting the file Post: 302656159

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Top Forums Shell Programming and Scripting Uncommenting the file Post 302656159 by ddreggors on Thursday 14th of June 2012 10:08:10 AM

06-14-2012

Registered User

I know this is not a sed solution but in vim you can do a range based search replace. That way you can see what you have done and then undo if you don't want to keep that change..

open file in vim and do the following:

Code:

:6,$s/^#//

Then if you don't like what it did:

Code:

To explain...

The ":" places you in command mode in vi/vim. The "6,$" is telling vi/vim to start at line "6" and end at "$" (end of file). Then the "s/^#//" tells vi/vim that we are doing a search/replace operation. Searching for "#" at the beginning of the line (^) and then in the replace side we leave blank to remove the "#" if found.

Just like sed, "s/<search>/<replace>/" uses regex. You can use regex patterns as normal in the search side. It even supports keeping part of the found string as in sed. Use "(" and ")" in the search and "\1" in the replace.

The undo is easy... simply make sure you are not in command mode by hitting the "ESC" key and then hit "u" to undo your changes (Ctrl+r for redo).

Cheers

ddreggors

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bup-margin

bup-margin(1)						      General Commands Manual						     bup-margin(1)

NAME

       bup-margin - figure out your deduplication safety margin

SYNOPSIS

       bup margin [options...]

DESCRIPTION

       bup margin  iterates  through  all  objects  in	your  bup repository, calculating the largest number of prefix bits shared between any two
       entries.  This number, n, identifies the longest subset of SHA-1 you could use and still encounter a collision between your object ids.

       For example, one system that was tested had a collection of 11 million objects (70 GB), and bup margin returned 45.  That  means  a  46-bit
       hash  would be sufficient to avoid all collisions among that set of objects; each object in that repository could be uniquely identified by
       its first 46 bits.

       The number of bits needed seems to increase by about 1 or 2 for every doubling of the number of objects.  Since SHA-1 hashes have 160 bits,
       that  leaves 115 bits of margin.  Of course, because SHA-1 hashes are essentially random, it's theoretically possible to use many more bits
       with far fewer objects.

       If you're paranoid about the possibility of SHA-1 collisions, you can monitor your repository by running bup margin occasionally to see	if
       you're getting dangerously close to 160 bits.

OPTIONS

       --predict
	      Guess  the offset into each index file where a particular object will appear, and report the maximum deviation of the correct answer
	      from the guess.  This is potentially useful for tuning an interpolation search algorithm.

       --ignore-midx
	      don't use .midx files, use only .idx files.  This is only really useful when used with --predict.

EXAMPLE

	      $ bup margin
	      Reading indexes: 100.00% (1612581/1612581), done.
	      40
	      40 matching prefix bits
	      1.94 bits per doubling
	      120 bits (61.86 doublings) remaining
	      4.19338e+18 times larger is possible

	      Everyone on earth could have 625878182 data sets
	      like yours, all in one repository, and we would
	      expect 1 object collision.

	      $ bup margin --predict
	      PackIdxList: using 1 index.
	      Reading indexes: 100.00% (1612581/1612581), done.
	      915 of 1612581 (0.057%)

SEE ALSO

       bup-midx(1), bup-save(1)

BUP

       Part of the bup(1) suite.

AUTHORS

       Avery Pennarun <apenwarr@gmail.com>.

Bup unknown-															     bup-margin(1)