How to do exactly depends on what your file contains.
For instance, taking the simplest case that the file itself contains just dates but not other fields, then it is pretty straightforward (assuming the file is not extremely large):
Code:
use Date::Parse;
open FILE, "<MyDates.txt";
my @dates = <FILE>;
my @sorted_dates = sort {
str2time($a) <=> str2time($b)
} @dates;
foreach (@sorted_dates) {
print $_;
}
Input File:
21 Dec 2005
23 Oct 2002
8 June 2004
Output:
23 Oct 2002
8 June 2004
21 Dec 2005
If the date is a certain column of the file, you may need to do some data extraction in the sort() block. How to do depends on the structure of your file. This is just a simple example to illustrate the idea.
Code:
use Date::Parse;
open FILE, "<MyDates2.txt";
my @dates = <FILE>;
my @sorted_dates = sort {
my ($d1, $d2) = map { /^(.+):.+$/ && $1 } ($a, $b);
str2time($d1) <=> str2time($d2)
} @dates;
foreach (@sorted_dates) {
print $_;
}
Input file:
21 Dec 2005:Event A
23 Oct 2002:Event B
8 June 2004:Event C
Output:
23 Oct 2002:Event B
8 June 2004:Event C
21 Dec 2005:Event A
Hi,
I have an entry file for a perl script from which I need to remove duplicate entry.
For example:
one:two:three
one:four:five
two:one:three
must become :
one:two:three
two:one:three
The duplicate entry is only the first field. I try many options of sort system command but don't... (4 Replies)
Perl file::find can I sort the out put
I am using file::find in my script but how I wish to process each file found in date order.
Can I sort this module?
eg
part of current script is....
use File::Find;
# Recursively find all files and directories in $mqueue_directory
find(\&wanted,... (2 Replies)
Hi,
I have a file of names and I want perl to do a sort on this file. How can I sort this list of names using perl? I'm thinking of a command like:
@sorted = sort { lc($a) cmp lc($b) } @not_sorted # alphabetical sort
The only thing I'm sort of unsure of is, how would I get the name in my... (6 Replies)
hello
i have a requirement where i have a direcotry in which i get files in the format
STOCKS.20080114.dat
STOCKS.20080115.dat
STOCKS.20080117.dat
STOCKS.20080118.dat
i need to loop through the directory and sort by create date descending order and i need to process the first file.
... (1 Reply)
hi all
i want help in sortng date in paragraphs within file ,
i want to ask as if there any option to sort a certain pattern of file not the rest of file.i.e the data of file become sorted with respect to date
i have a log file as follows
!! *A0628/081 /08-01-10/13 H... (1 Reply)
I need to extract the date part from the file name (20080221 in this ex) and compare it with the current date and delete it, if it is a past date.
$file = exp_ABCD4_T-2584780_upto_20080221.dmp.Z
really appreciate any help.
thanks
mkneni (4 Replies)
Hi All,
I am having a pipe delimited file .In this file the 3rd column is having date values.I need to get the min date and max date from that file.
I have used
cut -d '|' test.dat -f 3|sort -u
But it is not sorting the date .How to sort the date column using unix commands
Thanks ... (4 Replies)
I now have a 230,000+ lines long text file formatted in segments like this:
Is there a way to sort this file to have everything in chronological order, based on the date and time in the text? In this example, I would like the result to be: (19 Replies)
Hello All,
Need a shell script to sort entries in a file by date and time. Below are the entries in the file, i need to sort it first by the date and then time
Note :- Date is in MM/DD/YY format and date comes as the 6th & time comes on 7th coloumns respectively.
150 pbnawldb001-b... (10 Replies)
Hi Experts,
I have a filelist collected from another server , now want to sort the output using date/time stamp filed.
- Filed 6, 7,8 are showing the date/time/stamp.
Here is the input:
#----------------------------------------------------------------------
-rw------- 1 root ... (3 Replies)
Discussion started by: rveri
3 Replies
LEARN ABOUT CENTOS
sort
sort(3pm) Perl Programmers Reference Guide sort(3pm)NAME
sort - perl pragma to control sort() behaviour
SYNOPSIS
use sort 'stable'; # guarantee stability
use sort '_quicksort'; # use a quicksort algorithm
use sort '_mergesort'; # use a mergesort algorithm
use sort 'defaults'; # revert to default behavior
no sort 'stable'; # stability not important
use sort '_qsort'; # alias for quicksort
my $current;
BEGIN {
$current = sort::current(); # identify prevailing algorithm
}
DESCRIPTION
With the "sort" pragma you can control the behaviour of the builtin "sort()" function.
In Perl versions 5.6 and earlier the quicksort algorithm was used to implement "sort()", but in Perl 5.8 a mergesort algorithm was also
made available, mainly to guarantee worst case O(N log N) behaviour: the worst case of quicksort is O(N**2). In Perl 5.8 and later,
quicksort defends against quadratic behaviour by shuffling large arrays before sorting.
A stable sort means that for records that compare equal, the original input ordering is preserved. Mergesort is stable, quicksort is not.
Stability will matter only if elements that compare equal can be distinguished in some other way. That means that simple numerical and
lexical sorts do not profit from stability, since equal elements are indistinguishable. However, with a comparison such as
{ substr($a, 0, 3) cmp substr($b, 0, 3) }
stability might matter because elements that compare equal on the first 3 characters may be distinguished based on subsequent characters.
In Perl 5.8 and later, quicksort can be stabilized, but doing so will add overhead, so it should only be done if it matters.
The best algorithm depends on many things. On average, mergesort does fewer comparisons than quicksort, so it may be better when
complicated comparison routines are used. Mergesort also takes advantage of pre-existing order, so it would be favored for using "sort()"
to merge several sorted arrays. On the other hand, quicksort is often faster for small arrays, and on arrays of a few distinct values,
repeated many times. You can force the choice of algorithm with this pragma, but this feels heavy-handed, so the subpragmas beginning with
a "_" may not persist beyond Perl 5.8. The default algorithm is mergesort, which will be stable even if you do not explicitly demand it.
But the stability of the default sort is a side-effect that could change in later versions. If stability is important, be sure to say so
with a
use sort 'stable';
The "no sort" pragma doesn't forbid what follows, it just leaves the choice open. Thus, after
no sort qw(_mergesort stable);
a mergesort, which happens to be stable, will be employed anyway. Note that
no sort "_quicksort";
no sort "_mergesort";
have exactly the same effect, leaving the choice of sort algorithm open.
CAVEATS
As of Perl 5.10, this pragma is lexically scoped and takes effect at compile time. In earlier versions its effect was global and took
effect at run-time; the documentation suggested using "eval()" to change the behaviour:
{ eval 'use sort qw(defaults _quicksort)'; # force quicksort
eval 'no sort "stable"'; # stability not wanted
print sort::current . "
";
@a = sort @b;
eval 'use sort "defaults"'; # clean up, for others
}
{ eval 'use sort qw(defaults stable)'; # force stability
print sort::current . "
";
@c = sort @d;
eval 'use sort "defaults"'; # clean up, for others
}
Such code no longer has the desired effect, for two reasons. Firstly, the use of "eval()" means that the sorting algorithm is not changed
until runtime, by which time it's too late to have any effect. Secondly, "sort::current" is also called at run-time, when in fact the
compile-time value of "sort::current" is the one that matters.
So now this code would be written:
{ use sort qw(defaults _quicksort); # force quicksort
no sort "stable"; # stability not wanted
my $current;
BEGIN { $current = print sort::current; }
print "$current
";
@a = sort @b;
# Pragmas go out of scope at the end of the block
}
{ use sort qw(defaults stable); # force stability
my $current;
BEGIN { $current = print sort::current; }
print "$current
";
@c = sort @d;
}
perl v5.16.3 2013-03-04 sort(3pm)