Variable assignments specified with eval shell built-in
According to the POSIX specifications eval is a special shell built-in, which should imply that variable assignments specified together with it should remain in effect after the built-in completes. Thus one would expect IFS to be changed after this:
But it isn't:
Last edited by fpmurphy; 01-08-2011 at 11:43 AM..
Reason: fixed link
Im facing problem in assigning value of eval array variable as normal variable..
x=0
eval DATA${x}="FJSVcpcu"
x=`expr $x + 1`
eval DATA${x}="FJSVcsr"
if x=0, type -> eval echo \$DATA$x , its give me FJSVcpcu
i want assign this value into an variable as
variable=`eval echo... (3 Replies)
Hi,
I have multiple functions that can be called by any shell script. These functions have inbuilt echo statements to logs their activity into a log file. When I run multiple shell scripts that call these functions, they all log into the same log file and I am not able to differentiate which... (2 Replies)
Hello,
I have a script that does an scp to a server and then gets the number of process running on that server, the o/P should be stored in a variable for further processing
eval `echo "ssh -q $Infa_user@$host 'csh -c $CMD '"`
where
CMD="ps -ef | grep -i ${INFA_REPO} | grep -v grep | wc... (2 Replies)
Hi,
i have an issue with eval and variable assignment.
1) i have a date value in a variable and that date is part of a filename,
var1=20100331
file1=${var1}-D1-0092.xml.zip
file2=${var2}-D2-0092.xml.zip
file3=${var3}-D3-0092.xml.zip
i am passing the above variables to a script via... (11 Replies)
Hi Gurus,
I am having 2 parameters as below
parm1=value1
parm2=parm1
I want to evaluate parm1 value using eval echo \$$parm2 and later i want to assign this value to other variable which i will be using in if statement like :
if ]; then
do this.......
fi
could you please suggest... (5 Replies)
Hi guys,
Does awk have a built-in variable which I can use to display the input file it's currently reading?
I'm currently concatenating multiple files using awk and later on do some parsing. But for now, I want to add an extra column in the main output data file - basically putting in the... (3 Replies)
Hi all,
I'm not exactly a shell script guru, so this is probably a very silly question and I'm not seeing the point, but you know, sometimes it happens...
I have this script which adds entries to local arp cache using it to find the corresponding IP address.
# export MAC=00:25:90:34:3d:f2... (16 Replies)
pattern1=book
{
x=1
eval echo \$pattern$x
}
book (this is the output)
But when I assign a variable to the output of the eval it doesn't work unless I prefix 2 times backslash before $ as shown below.
{
a=`eval echo \\$pattern$x`
echo $a
}
book
Why here twice "\" has to be... (3 Replies)
Is there a safe way to evaluate variable declarations within a script whether they come from a .conf file, user input, or stdin?
Example .conf file:
server=ftp.xxxx.com
port=21
user="$USER" # Hopefully allow this type of substitution
domain="$DOMAIN"
server="$(malicious... (4 Replies)
Discussion started by: Michael Stora
4 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)