I have a SQL script that requires values from the environment in order to execute. I found a way to get the desired results but my process is a little choppy. Any suggestions on how to clean this up would be greatly appreciated.
SQL Script
-------------
select a, b, c
from d
where a =... (1 Reply)
I have written a script to ftp a file from Unix to an NT machine to authenticate ftp login I have added the information into the .netrc file when logged in using ftp the commands are not executed. Does anybody know how to make the command execute once username and password have been provided using... (2 Replies)
Basically, I would like to run an mpirun query on my web server to query your databases via yours when using the BLAST program, however the server seems not able to execute even basic mpirun programs such as cpi (to calculate pi). Are there any settings I should take note of?
I am running Perl... (0 Replies)
Hi, guys !
I have at home a simple network. I have a server that shares the internet connection to my computer and another another computer which is located in another room. When I want to download something, I'd like to download directly on the server, without letting my computer on. The server... (2 Replies)
Hi Folks,
I have a small doubt, the binary commands under /bin and /sbin as well as other path binary files, if you peek deep into that, you can find the difference in the way of normal perl programming and some commands will be like binary files. how are the commands executing like the... (3 Replies)
Hi Friends,
I have a situation here, where I have a script running in one server, namely "SERVER1". Within this script which runs in SERVER1, I have a set of commands which has to connect to a different server (namely "SERVER2") and execute the commands accordingly. I have no experience at all... (1 Reply)
I need to execute a command to run my script several times with varying parameters
perl ex.pl -b 130198 -e 130884 -c plot plot.txt 1_plot.txt
perl ex.pl -b 1345 -e 1308 -c plot plot.txt 2_plot.txt
perl ex.pl -b 1345567 -e 130898 -c plot plot.txt 3_plot.txt
.
.
.
100's of excutions
... (2 Replies)
Hi,
I am stuck into a situation where i want to execute a command in my shell script well along with a previous command in order to achieve something but i am not figuring out a way.
here is a snippet:
service management restart
rm -rf lock.file
in the above, if you see, i am trying to... (5 Replies)
Hello.
I am new in shell script. Could anyone help me?
I have un shell script. I need each command in it be sequentielly, when the first command ends the second starts. When the second ends et third starts, and so on
Thanks in adavance (1 Reply)
If you want to capture the output of any command, we then will be writing the system command in `` or qx.
`` an qx works fine with all linux and windows system commands.
But when I execute the below code.. it is displaying the output on the screen directly instead of storing to variable
... (3 Replies)
Discussion started by: giridhar276
3 Replies
LEARN ABOUT OSX
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 v5.16.2 2012-08-26 sort(3pm)