11-04-2008
10 More Discussions You Might Find Interesting
1. UNIX for Dummies Questions & Answers
Does anyone know how to use grep/egrep to find a string that contains a null character?
i.e.: the string looks like this: null0001nullN
well I want to be able to : grep '0001N'
is there a wildcard character or something that I can put in the grep to include the nulls? (3 Replies)
Discussion started by: weerich
3 Replies
2. UNIX for Dummies Questions & Answers
Hi,
suppose you have the following line at your crontab :
5 * * * * /usr/mine/script > /dev/null 2>&1
now i understood that the " > /dev/null 2>&1 outputs both Standard outpout and Standard Error messages to the /dev/null device or file...
the first part , " > /dev/null " transfers... (1 Reply)
Discussion started by: BAM
1 Replies
3. UNIX for Advanced & Expert Users
I'm testing out some ESMTP AUTH stuff, and it requires that the username and password be on the same line separated by a null character. Does anyone know how to echo the ASCII null character?
Thanks,
Alex (3 Replies)
Discussion started by: vertigo23
3 Replies
4. UNIX for Dummies Questions & Answers
Hi,
I would like to use grep to find files which contain NULL characters. I'm not sure how to represent the null character in the grep statement.
Could anyone help please?
Thanks!
Helen :confused: (5 Replies)
Discussion started by: Bab00shka
5 Replies
5. Shell Programming and Scripting
Hi All,
I have a problem with Null values while reading line by line from a text file. I wrote a shell script to read set of file names from a text file line by line, and zipping the each individual file and copying those zip files into some separate directory, and removing the original file... (3 Replies)
Discussion started by: npk2210
3 Replies
6. UNIX for Dummies Questions & Answers
How are these two different? They both prevent output and error from being displayed. I don't see the use of the "&"
echo "hello" > /dev/null 2>&1
echo "hello" > /dev/null 2>1 (3 Replies)
Discussion started by: glev2005
3 Replies
7. Shell Programming and Scripting
Hi All,
I am writting a Sell Script, that takes Search String & File Name from the terminal and check for Null Status. If either is NULL then pgm should quit.
I wrote the following:
bash-3.2$ cat null_status_of_parameters.sh
#!/bin/sh
#WASS that takes Search String & File Name from... (2 Replies)
Discussion started by: manishdivs
2 Replies
8. UNIX for Advanced & Expert Users
I have a huge file with record length around 5000 characters.
There is an ETL tool datastage which is writing this data to the file(AIX server). At position 4095 i have seen NULL Character(^@).
when i am using this command "head -1 file_nm | sed 's/\000//g'" --- the output is displaying... (3 Replies)
Discussion started by: issaq84mohd
3 Replies
9. Shell Programming and Scripting
We have a flat file with below data :
^@^@^@^@00000305^@^@^@^@^@^@430^@430^@^@^@^@^@^@^@^@^@09079989530As we can see ^@ is Null character in this file
I want to remove only the first few null characters before string 00000305
How can we do that, any idea. I want a new file without first few... (5 Replies)
Discussion started by: simpltyansh
5 Replies
10. AIX
Hello,
Does anyone know how to housekeeping the null 2>&1 file in /dev?
its fill up my system, please help.
Thanks :b: (3 Replies)
Discussion started by: only
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)