Indirect variables in Bash Post: 302769088

9 More Discussions You Might Find Interesting

1. UNIX for Advanced & Expert Users

Compound indirect variable references

Using bash, I'm trying to read a .properties file (name=value pairs), assigning an indirect variable reference for each line in the file. The trick is that a property's value string may contain the name of a property that occurred earlier in the file, and I want the name of the 1st property to...

2. Shell Programming and Scripting

Length of an indirect variable

The construct ${#parameter} returns the number of characters in the parameter and ${!parameter} specifies an indirect variable. My question is: How do I combine these two. What I want is ${#!parameter} but this gives an error. Of course I can use: dummy=${!parameter} ${#dummy} but that's a...

3. Shell Programming and Scripting

Bash variables

Ummm can anybody help me with this one? Its prob quite simple. I bascially have a file name say J1x2x3x7.dat Im using the file name as a variable in a bash script. Want I want to do is extract most of the file name and make it a new variable expect with say one of the number now a...

4. Linux

How to get an Indirect Variable Value..?

Hi, I've got a small problem. If varible A stores "B" and Variable B stores C, How to get the value of variable B by using only Variable A..? I tried the following but didnt work pease help.. $ var1=vikram $ echo $var1 vikram $ vikram=sampath $ echo $vikram sampath $ echo...

5. Shell Programming and Scripting

Indirect variable assignment

Hi I have variable A_B=alpha also var1="A" var2="B" I want to retrieve the value alpha using var1 and var2 , somthing like echo ${${var1}_${var2}} that works. Obviously this is receiving syntax error

6. Shell Programming and Scripting

Does SH support indirect expansion like BASH?

Hello, is there a kind soul who can answer me, does the SH support double substitution known as indirect expansion similar to BASH? The syntax for bash is ${!var}. For instance in bash I can write something like this: VAR="value" REF_VAR="VAR" echo ${!REF_VAR} and get the "value"...

7. Shell Programming and Scripting

Indirect Referral Script

I have a file with two columns of numbers (member IDs): 1 1 2 1 3 1 4 2 5 4 6 1 7 5 8 3 9 2 Think of column 1 as the referee and column 2 as the referrer. Is there a good way to backtrack who referred who? I would like an output, for this example here to be: 1 1 2 1 3 1 4 2 1

8. Shell Programming and Scripting

BASH arrays and variables of variables in C++

Sometimes it is handy to protect long scripts in C++. The following syntax works fine for simple commands: #define SHELLSCRIPT1 "\ #/bin/bash \n\ echo \"hello\" \n\ " int main () { cout <<system(SHELLSCRIPT1); return 0; } Unfortunately for there are problems for: 1d arrays:...

9. Shell Programming and Scripting

Passing awk variables to bash variables

Trying to do so echo "111:222:333" |awk -F: '{system("export TESTO=" $2)}'But it doesn't work

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)