Visit Our UNIX and Linux User Community

Linux and UNIX Man Pages

Test Your Knowledge in Computers #811
Difficulty: Easy
RGBA stands for red green blue alpha.
True or False?
Linux & Unix Commands - Search Man Pages

bup-tag(1) [debian man page]

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

NAME
bup-tag - tag a commit in the bup repository SYNOPSIS
bup tag bup tag <tag name> <committish> bup tag -d <tag name> DESCRIPTION
bup tag lists, creates or deletes a tag in the bup repository. A tag is an easy way to retreive a specific commit. It can be used to mark a specific backup for easier retrieval later. When called without any arguments, the command lists all tags that can be found in the repository. When called with a tag name and a com- mit ID or ref name, it creates a new tag with the given name, if it doesn't already exist, that points to the commit given in the second argument. When called with '-d' and a tag name, it removes the given tag, if it exists. bup exposes the contents of backups with current tags, via any command that lists or shows backups. They can be found under the /.tag directory. For example, the 'ftp' command will show the tag named 'tag1' under /.tag/tag1. Tags are also exposed under the branches from which they can be reached. For example, if you create a tag named 'important' under branch 'computerX', you will also be able to retrieve the contents of the backup that was tagged under /computerX/important. This is done as a convenience, and should the branch 'computerX' be deleted, the contents of the tagged backup will be available through /.tag/important as long as the tag is not deleted. OPTIONS
-d, --delete delete a tag EXAMPLE
$ bup tag new-puppet-version hostx-backup $ bup tag new-puppet-version $ bup ftp "ls /.tag/new-puppet-version" files.. $ bup tag -d new-puppet-version SEE ALSO
bup-save(1), bup-split(1), bup-ftp(1), bup-fuse(1), bup-web(1) BUP
Part of the bup(1) suite. AUTHORS
Gabriel Filion <lelutin@gmail.com>. Bup unknown- bup-tag(1)

Check Out this Related Man Page

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)

Featured Tech Videos