Is it possible to combine a regular expression with a aritmetical expression? For example, taking a 8-numbers caracter sequece and casting each output of a grep, comparing to a constant.
THX! (2 Replies)
What does the regular expression +~).*'] mean while using it with regexec.When the string "RCHNUSNT35C~rs07/ASM-RS07" is used with the regular expression +~).*'] regexec gives an error. I know what regexec does,but i do not understand what this expression means wrt to this string...
any help... (2 Replies)
I currently list and sort all the files in a directory which begin with an Upper Case C and end with the extension '#finished#'.
Here is the command I use:
ls -tr $currentDir/*.#finished#
what i need to do now is list all the files in a directory that begin with upper case C and end... (3 Replies)
CA_RELEASE has a value of 6. I need to check if that this is a numeric value. if not error.
source $CA_VERSION_DATA
if * ]
then
echo "CA_RELESE $CA_RELEASE is invalid"
exit -1
fi
+ source /etc/ncgl/ca_version_data
++ CA_PRODUCT_ID=samxts
++ CA_RELEASE=6
++ CA_WEEK_NO=7
++... (3 Replies)
Hi all,
How am I read a file, find the match regular expression and overwrite to the same files.
open DESTINATION_FILE, "<tmptravl.dat" or die "tmptravl.dat";
open NEW_DESTINATION_FILE, ">new_tmptravl.dat" or die "new_tmptravl.dat";
while (<DESTINATION_FILE>)
{
# print... (1 Reply)
Hello All,
I'm trying to extract the lines between two consecutive elements of an array from a file.
My array looks like:
problem_arr=(PRS111 PRS213 PRS234)
j=0
while } ]
do
k=`expr $j + 1`
sed -n "/${problem_arr}/,/${problem_arr}/p" problemid.txt
---some operation goes... (11 Replies)
Hi,
I am quite knew to scripting and I am trying to get a regular expression to work to check that a user enters a valid version number such as 1 or 1.1 or 12.3 etc. I dont seem to be able to get it to work as it picks up versions such as 1.......2. I only want it to work with a single dot.... (12 Replies)
I would like to extract "JDBC Thin Client" from (PROGRAM=JDBC Thin Client); and "C:\Python26\python.exe" from (PROGRAM=C:\Python26\python.exe); "txm_v_awsrf_db.pr" from (PROGRAM=txm_v_awsrf_db.pr).
if input line like "(PROGRAM=)", it return unknown.
Would you help suggest a regular... (4 Replies)
Discussion started by: cstsang
4 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)
12-12-2011
