Please help me out: I've seen this construct
several times, like in scrutinizer's today's post
but I can't find (manuals, man pages, internet FAQs,...) an explanation of what it does resp. stands for. Any hint is appreciated!
Hi all
I have tried to search for this, but keep getting a MySQL db connect error, so am posing the question here, and taking a risk of incurring the wrath of the mods with my first post...
I have the following test script:
#!/bin/bash
HTTPD=`/bin/ps -axcu | /usr/bin/grep httpd... (6 Replies)
Hi Guys,
could someone tell me what this ksh construct does
typeset -r PROG_PWD=${0%/*} does
I understand the -r for readonly but I would very much appreciate a definitive account of what this will set $PROG_PWD to.
If I run this at the cmd line it it gets set to /usr/bin but I would... (2 Replies)
I was checking my error logs today and ran into some errors I have not seen before maybe somebody has run into these before?
/etc/cron.quarter-hourly/owusers.sh:
Set effective gid to mail(12) failed!
/usr/local/mailwatch/check_sendmail_relay.sh: line 8:
thanks (1 Reply)
Hi all,
Sorry to ask this easy question but I am stuck. In a scenario i am executing one shell script which contains a if - else construct :
if ; then
echo $line
$line >> successful_build.txt
else
$line >> failed_services.txt
fi
explaination : if the... (5 Replies)
I recently was handed responsibility for a script which has array references that are new to me and I could use some help understanding them.
Parts of the config file and script are included. This script collects backups from a jail server of the jails running on that host. Several jail... (1 Reply)
Hi all
i have been trying to do a small 'question and answer' script using if-else statement and a combination of pipe. I have succeeded in allowing the user to login with user name and password stored in a sequence username/password in a file named "pass" like this:
echo "please enter your... (14 Replies)
Hi,
I need to construct the below path from the two available directory path,
O/P
/home/data/test/run/ht/WEB/HTML
/home/data/test/run/ht/WEB/JSP
/home/data/test/run/ht/WEB/CSS
Path:1
------
/home/data/test/run/
Path:2
------
/home/data/share/app/01/lang/ht/WEB/HTML... (5 Replies)
Hi all,
I thought this would be simple, but I've been having a lot of trouble trying to write this IF statement, if I may ask for help pls:
In BASH, how would I construct the if statement:
Should ONLY be true if USEROPTscript=="yes"]] AND $mode=="INSTALL" /or/ $mode=="CHANGE" ]]... (3 Replies)
Discussion started by: jmccoughlin
3 Replies
LEARN ABOUT DEBIAN
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)