Hi,
I have a shell script. What should I do to allow only single instance of the script to be run by a user at a time. That is, Only one user can run that script at a given point of time.
Please help..
Its very important for my project
Thanks in advance (4 Replies)
Hi,
I have a script. I want only one instance of the script to be running at any point of the time. How can I do it.
what would be the exact format of the ps command for doing this. For example the name of my script is "Inst.sh"
Thanx in advance (2 Replies)
Hi there, if i have a simple getopts like below ...how can i make it so that if somebody enters more than one -g argument for example, it will error with a " you cannot enter more than one -g" or something like that.?
I want to only allow one instance of a -g or a -h etc ..
while getopts... (1 Reply)
Hi All,
I have searched the forum but couldn't find exactly what I need. Hopefully someone may be able to help.
I'm trying to put a script together that will extract numbers from a text file and multiply them by, for example 1.5 or 1.2
Sample file looks like this...... (1 Reply)
There are a lot of ways to extract text from between two strings, but what if those strings occur multiple times and you only want the text from the first two strings? I can't seem to find anything to work here. I'm using sed to process the text after it's extracted, so I prefer a sed answer, but... (4 Replies)
Hello,
I did offline HACMP(PowerHA) upgrade 5.4.1 to 5.5 - basically stopped HACMP services and upgraded cluster.* filesets.
Tried to start services again - topsvcs refused to start on second node complaining that node instance numbers are different - and indeed they are different.
This is... (2 Replies)
Hi All
I need help
am having a source file as below
emp
dept
class
subclass
region
country
division
first i need to get line count and i need to divide by 3 it is an parameter passing value
number of lines 7 (8 Replies)
Hi I am part of a academic organization and I want to send a fax to the students however there must be a quicker way to get the fax numbers extracted from the online forms they sent me.
The file looks like this (numbers are fake in order to protect identity):
Biochemistry Major
Michael... (3 Replies)
Hi,
I want to write one program in C in Unix OS which will check the running status of a process time to time. If the process is stopped somehow by any means, it will ensure that the process is restarted and only one copy of the process image should run in memory at any point of time for the user.... (2 Replies)
I have a csv dataset like this :
C,rs18768
G,rs13785
GA,rs1065
G,rs1801279
T,rs9274407
A,rs730012
I'm thinking of use like awk, sed to covert the dataset to this format: (if it's two character, then keep the same)
CC,rs18768
GG,rs13785
GA,rs1065
GG,rs1801279
TT,rs9274407... (7 Replies)
Discussion started by: nengcheng
7 Replies
LEARN ABOUT PHP
debug_zval_dump
DEBUG_ZVAL_DUMP(3) 1 DEBUG_ZVAL_DUMP(3)debug_zval_dump - Dumps a string representation of an internal zend value to outputSYNOPSIS
void debug_zval_dump (mixed $variable, [mixed $...])
DESCRIPTION
Dumps a string representation of an internal zend value to output.
PARAMETERS
o $variable
- The variable being evaluated.
RETURN VALUES
No value is returned.
EXAMPLES
Example #1
debug_zval_dump(3) example
<?php
$var1 = 'Hello World';
$var2 = '';
$var2 =& $var1;
debug_zval_dump(&$var1);
?>
The above example will output:
&string(11) "Hello World" refcount(3)
Note
Beware the refcount
The refcount value returned by this function is non-obvious in certain circumstances. For example, a developer might expect the
above example to indicate a refcount of 2. The third reference is created when actually calling debug_zval_dump(3).
This behavior is further compounded when a variable is not passed to debug_zval_dump(3) by reference. To illustrate, consider a
slightly modified version of the above example:
Example #2
<?php
$var1 = 'Hello World';
$var2 = '';
$var2 =& $var1;
debug_zval_dump($var1); // not passed by reference, this time
?>
The above example will output:
string(11) "Hello World" refcount(1)
Why refcount(1)? Because a copy of $var1 is being made, when the function is called.
This function becomes even more confusing when a variable with a refcount of 1 is passed (by copy/value):
Example #3
<?php
$var1 = 'Hello World';
debug_zval_dump($var1);
?>
The above example will output:
string(11) "Hello World" refcount(2)
A refcount of 2, here, is extremely non-obvious. Especially considering the above examples. So what's happening?
When a variable has a single reference (as did $var1 before it was used as an argument to debug_zval_dump(3)), PHP's engine opti-
mizes the manner in which it is passed to a function. Internally, PHP treats $var1 like a reference (in that the refcount is
increased for the scope of this function), with the caveat that if the passed reference happens to be written to, a copy is made,
but only at the moment of writing. This is known as "copy on write."
So, if debug_zval_dump(3) happened to write to its sole parameter (and it doesn't), then a copy would be made. Until then, the
parameter remains a reference, causing the refcount to be incremented to 2 for the scope of the function call.
SEE ALSO var_dump(3), debug_backtrace(3), References Explained, References Explained (by Derick Rethans).
PHP Documentation Group DEBUG_ZVAL_DUMP(3)