It is not a given that Perl will be any faster than Awk. In most cases it won't be.
Here is a code snippet that will get you started with multi-line records from a file:
Code:
#!/usr/bin/env perl
$i=0;
$throw_away=<DATA>; # read the first record delim...
while (defined($record=<DATA>)) {
if ($record !~ /recordstart/) {
$record .= <DATA>;
redo unless eof(DATA);
}
$record =~ s/^recordstart\Z//m;
# now you have the full record...
print "====record $i:\n$record\n";
$i++;
}
__DATA__
recordstart
val1 1
val2 2
val3 4
recordstart
val1 5
val2 6
val3 1
val4 1
recordstart
val1 1
val2 3
val3 6
An alternate is to use the Perl record separator to help you:
Code:
{
local $/="recordstart\n";
$throw_away=<DATA>;
$i=0;
while ($record=<DATA>) {
chomp $record;
$i++;
# now you have the individual records:
print "record $i:\n$record";
}
}
Hey everyone ...
I wanted to process the contents of a file, as in modify its contents. whats the best way to do it on perl? In more detail I hav to go through the contents of the file, match patterns n then modify the contents of the same file depending on the matching results. Any help is... (2 Replies)
I need a script to process a huge single line text file:
The sample of the text is:
"forward_inline_item": "Inline", "options_region_Australia": "Australia", "server_event_err_msg": "There was an error attempting to save", "Token": "Yes", "family": "Family","pwd_login_tab": "Enter Your... (1 Reply)
Qspace ABC
Queue doCol: true
Queue order: fifo
Queue setCol: red
Queue order: fifo
Qspace XYZ
Queue getCol: true
Queue order: fifo
I need to append every line in this file with Qspace & Queue, so that final o/p shall look like this,
Qspace: ABC Queue: doCol
Qspace: ABC Queue: doCol... (2 Replies)
I am trying to read in a 2 column data file into Perl Hash array index. Here is my code.
#!/usr/bin/perl -w
use strict;
use warnings;
my $file = "file_a";
my @line = ();
my $index = 0;
my %ind_file = ();
open(FILE, $file) or die($!);
while(<FILE>) {
chomp($_);
if ($_ eq '')
{
... (1 Reply)
Can Someone explain me why even using Tie::IxHash I can not get the output data in the same order that it was inserted? See code below.
#!/usr/bin/perl
use warnings;
use Tie::IxHash;
use strict;
tie (my %programs, "Tie::IxHash");
while (my $line = <DATA>) {
chomp $line;
my(... (1 Reply)
Hi,
In Perl, is it possible to use a range of numbers with '..' as a key in a hash?
Something in like:
%hash = (
'768..1536' => '1G',
'1537..2560' => '2G'
);
That is, the range operation is evaluated, and all members of the range are... (3 Replies)
Hi to everybody.
I have a script in AWK with a revursive function, when I make the recursive call I'm loosing values in the local variables. So I'm trying to do the script in Perl, but I don't know Perl.
I want to load several hashes with the data in a pipe separated file. In AWK it looks... (0 Replies)
Hi,
I have an hashes of hash, where hash is dynamic, it can be n number of hash. i need to compare data_count values of all .
my %result (
$abc => {
'data_count' => '10',
'ID' => 'ABC122',
}
$def => {
'data_count' => '20',
'ID' => 'defASe',
... (1 Reply)
Hello,
I extracted a list of files in a directory with the command ls . However this is not my computer, so the ls functionality has been revamped so that it gives the filesizes in front like this :
This is the output of ls command : I stored the output in a file filelist
1.1M... (5 Replies)
Discussion started by: ajayram
5 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)