Hi,
I have a database (a simple .dat file) which has multiple records (structure datatype) in it.
I would like to know if we can use write() system call to update/modify intermediate records in this file (using C). If so, could somegive give a code snippet of the same. :-)
Thanks in advance... (2 Replies)
Hi,
I just stuckup in doing some regular expressions on a file.
I have data which has multiple FHS and BTS segments like:
FHS|12121|LOCAL|2323
MSH|10101|POTAMAS|2323
PID|121221|THOMAS|DAVID|23432
OBX|2342|H1211|3232
BTS|0000|MERSTO|LIABLE
FHS|12121|LOCAL|2323
MSH|10101|POTAMAS|2323... (3 Replies)
problem with piping one output to another.Would like to avoid the intermediate file creation.The piping does nt work on places where files have been created and goes in an endless loop.
sed -e "s/^\.\///g" $LINE1| sed -e "s/_\(\)/kkk\1/g" > $file1
tr -s '_' ' ' < $file1| \
sort -n -k... (1 Reply)
I have a file with data extracted, and need to insert a header with a constant string, say: H|PayerDataExtract
if i use sed, i have to redirect the output to a seperate file like
sed ' sed commands' ExtractDataFile.dat > ExtractDataFileWithHeader.dat
the same is true for awk
and... (10 Replies)
Suppose host B does not allow public/private key authentication - only secureID authentication. I already have a master ssh connection from host A to host B. Host A does allow public/private key authentication. Is there any way to connect from host C to host B by way of the master ssh connection... (2 Replies)
Hi, I am running a script which produces a number of intermediate output files for each time step. is there a way to remove these intermediate files and just retain the final output at every end of the loop, like sort of an initialization process? this the inefficient way i do it.
for i in... (3 Replies)
I am trying to extract the file names alone, for example "TVLI_STATS_NRT_XLSTWS03_20120215_132629.csv", from below output
which was given by the grep.
sam:/data/log: grep "C10_Subscribe.000|subscribe|newfile|" PDEWG511_TVLI_JOB_STATS.ksh.201202*
Output:
... (6 Replies)
Hi,
Can maybe some of the UNIX-guys recommend an online UNIX intermediate level documentation with examples (not too dry :-).
More the post-beginner level, for someone who has to play around with files and directories, with chmod, grep, sed, a little awk maybe...
bw,
Omar KN
(once tasted... (2 Replies)
Dear Help,
I have an input file which looks like -
121 300
122 345
124 567
127 234
$1 has 125 and 126 missing. How can I output those missing values?
Thanks (6 Replies)
Discussion started by: Indra2011
6 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)