Here is one approach:
producing for your sample data:
and for your sample data and one non-matching file:
The syntax
is called process substitution. This also worked with "ksh 93s+". See man pages for details on specific commands.
If it is possible that the files could be very long, you could add a preliminary screening for size: check the length of the two files, if the lengths are different, then you need not sort and compare, but declare immediately that they are different ... cheers, drl
Last edited by drl; 08-08-2009 at 08:41 AM..
Reason: Edit 1: spelling correction
If I have 3 kinds of files in directory DATA1:
FileA.20060315.dat, FileB.20060315.dat, FileC.20060315.dat
FileC.20060316.dat
FileA.20060317.dat, FileB.20060317.dat
FileA.20060318.dat, FileB.20060318.dat, FileC.20060318.dat
If 3 files have the same date then run
$cat FileA.20060315.dat... (3 Replies)
Dear All.
Im trying to know how exactly the command "compare" works, does it compare line by line or field by field, and the most important thing is that why the files have to be sorted before we compare them?
Thanks in advance (7 Replies)
I have four files, I need to compare these files together.
As such i know "sdiff and comm" commands but these commands compare 2 files together. If I use sdiff command then i have to compare each file with other which will increase the codes.
Please suggest if you know some commands whcih can... (6 Replies)
Hello all -
I am to this forum and fairly new in learning unix and finding some difficulty in preparing a small shell script. I am trying to make script to sort all the files given by user as input (either the exact full name of the file or say the files matching the criteria like all files... (3 Replies)
Team,
I have two files and I am trying to find the lines unique to file1. So i have executed the below command at shell prompt and got the correct results
comm -23 <(sort test) <(sort test1)
When i run the same command in Bash shell script, i got the correct results.
But when i run... (5 Replies)
Hello All,
Iam using below method to sort and compare files. First iam doing sorting and changing the same file and then doing comparing and taking the final result to another file.
sort -o temp.txt file1
mv temp.txt file1
sort -o temp.txt file2
mv temp.txt file2
sort -o temp.txt... (6 Replies)
To make it easier, i gave following example. It is not homework or classwork. Instead, i have a huge csv file dump from tsql with 15 columns and around 300 rows. I was able to extract content that needs to be really converted. Here is the extract:
ES FP,B1ES FP,70000,I,SL22,SL22 (70000)
ES... (0 Replies)
To make it easier, i gave following example. It is not homework or classwork. Instead, i have a huge csv file dump from tsql with 15 columns and around 300 rows. I was able to extract content that needs to be really converted. Here is the extract:
ES FP,B1ES FP,70000,I,SL22,SL22 (70000)
ES... (8 Replies)
Hello,
I am new to Unix and would like to seek a help, please.
I have 2 files (file_1 and file_2), I need to perform the following actions.
1 ) Sort the both file by the column 26-36 (which is Invoice number)
what is sort command with the column sort?
2) Compare the file_1.sorted and... (3 Replies)
Discussion started by: Usagi
3 Replies
LEARN ABOUT MOJAVE
sort5.18
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 { $current = sort::current; }
print "$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 { $current = sort::current; }
print "$current
";
@c = sort @d;
}
perl v5.18.2 2013-11-04 sort(3pm)