what does this symbol ~ represent in unix for example....
If i create directories called personal and lab and lab5 and the command chmod 776~/lab5 is issued. What results would i expect to get. basically i know that chmod 776 would prevent others from executing the files in the directory but... (2 Replies)
Many scripts are executed in the following way.
. /scriptname
Even when the file does not have execute permission, it can be executed this way. How does this work? (6 Replies)
Hi,
I am a newbie in unix shell scripting and I am trying to understand the result of the following line :
ls -l $1*$4*ready
I understand the ls-l but the rest is just really confusing. Any help would be appreciated.
TIA (3 Replies)
Hello... I am getting ready to create a bunch of groups for several of our servers all of which are running Aix 5.3. We really want to keep people away from using the root login and as such the systems have been hardened using aixpert and if it is absolutely needed people must su -.
There are... (1 Reply)
What is the significance of the forward slash(/) while specifying a directory?
cp -av /dir/ /opt/
and
cp -av /dir /opt
Does effectively the same job it seems? (2 Replies)
I'm taking a LINUX and UNIX class and we are using bash as the shell in terminal. On my mac-book I use zsh only because my professor had a pretty cool start-up file for it.
It has benefited me in becoming familiar with different shells. However, I'm having a hard time understanding the purpose... (4 Replies)
Hi Everyone,
in the below "xyz (Exception e)" part... after the curly braces, there is a new line and immediately few tabs are present before closing curly brace.
xyz (Exception e) {
}
note: there can be one or more newlines between the curly braces.
My desired output should be ... (6 Replies)
Discussion started by: NY_777
6 Replies
LEARN ABOUT DEBIAN
devel::refcount
Devel::Refcount(3pm) User Contributed Perl Documentation Devel::Refcount(3pm)NAME
"Devel::Refcount" - obtain the REFCNT value of a referent
SYNOPSIS
use Devel::Refcount qw( refcount );
my $anon = [];
print "Anon ARRAY $anon has " . refcount($anon) . " reference
";
my $otherref = $anon;
print "Anon ARRAY $anon now has " . refcount($anon) . " references
";
DESCRIPTION
This module provides a single function which obtains the reference count of the object being pointed to by the passed reference value.
FUNCTIONS
$count = refcount($ref)
Returns the reference count of the object being pointed to by $ref.
COMPARISON WITH SvREFCNT
This function differs from "Devel::Peek::SvREFCNT" in that SvREFCNT() gives the reference count of the SV object itself that it is passed,
whereas refcount() gives the count of the object being pointed to. This allows it to give the count of any referent (i.e. ARRAY, HASH,
CODE, GLOB and Regexp types) as well.
Consider the following example program:
use Devel::Peek qw( SvREFCNT );
use Devel::Refcount qw( refcount );
sub printcount
{
my $name = shift;
printf "%30s has SvREFCNT=%d, refcount=%d
",
$name, SvREFCNT($_[0]), refcount($_[0]);
}
my $var = [];
printcount 'Initially, $var', $var;
my $othervar = $var;
printcount 'Before CODE ref, $var', $var;
printcount '$othervar', $othervar;
my $code = sub { undef $var };
printcount 'After CODE ref, $var', $var;
printcount '$othervar', $othervar;
This produces the output
Initially, $var has SvREFCNT=1, refcount=1
Before CODE ref, $var has SvREFCNT=1, refcount=2
$othervar has SvREFCNT=1, refcount=2
After CODE ref, $var has SvREFCNT=2, refcount=2
$othervar has SvREFCNT=1, refcount=2
Here, we see that SvREFCNT() counts the number of references to the SV object passed in as the scalar value - the $var or $othervar
respectively, whereas refcount() counts the number of reference values that point to the referent object - the anonymous ARRAY in this
case.
Before the CODE reference is constructed, both $var and $othervar have SvREFCNT() of 1, as they exist only in the current lexical pad. The
anonymous ARRAY has a refcount() of 2, because both $var and $othervar store a reference to it.
After the CODE reference is constructed, the $var variable now has an SvREFCNT() of 2, because it also appears in the lexical pad for the
new anonymous CODE block.
PURE-PERL FALLBACK
An XS implementation of this function is provided, and is used by default. If the XS library cannot be loaded, a fallback implementation in
pure perl using the "B" module is used instead. This will behave identically, but is much slower.
Rate pp xs
pp 225985/s -- -66%
xs 669570/s 196% --
SEE ALSO
o Test::Refcount - assert reference counts on objects
AUTHOR
Paul Evans <leonerd@leonerd.org.uk>
perl v5.14.2 2011-11-15 Devel::Refcount(3pm)