Solved

have function to check file whether are opening

Posted on 2000-03-22
16
194 Views
Last Modified: 2006-11-17
have function to check a file whether are open?
0
Comment
Question by:gameboss
  • 7
  • 4
  • 3
  • +2
16 Comments
 
LVL 8

Expert Comment

by:us111
Comment Utility
hmm I don't know a function which tell you if the file is opened
Try that:

<?
  $f = fopen("myfile.txt", "r");
  if ($f <> false)
       print "The file is opened";
?>
0
 
LVL 2

Expert Comment

by:maxkir
Comment Utility
No.
0
 

Expert Comment

by:mrvithan
Comment Utility
I amn't quite sure but it may depend on the software. If it locks the file, of couse you can't open it.
0
 

Author Comment

by:gameboss
Comment Utility
I want use it in a multi users system.
multi user want write same file ,
when one user open a file,other user can get a message and exec another program,I do not want other user get  error message.
0
 
LVL 8

Expert Comment

by:us111
Comment Utility
well I have no idea how we can do that.......
Create a database with filename and opened as fields.

if an user opens a file : update the database with filename and opened=true
on close: opened=false

if an user opens a file which is already opened : check the filename in the database.

It could be a solution
0
 
LVL 2

Expert Comment

by:gravity
Comment Utility
Some pseudo code (how *do* you spell pseudo ?)

Check to see if lock file exists and put result in $open
while ($open==false) {
write lock file
open file
do whatever with file
close file
unlink lock file
check to see if lock file exists and put result in $open
}

Hope that enlightens.
0
 
LVL 8

Expert Comment

by:us111
Comment Utility
gravity has right too
0
 
LVL 2

Expert Comment

by:maxkir
Comment Utility
Try this code, i didn't test it.

$fp = fopen($filename, "w");

$attempts = 0
while ( !flock($fp, 2) && ($attempts++ < 10) )
{
   // file is locked by someone else
   sleep(1);
}

if ($attempts == 10)
{
   fclose($fp);
   die("unable to aquire a lock");
}

// We get a lock
// Do things
fwrite($fp, "Stuff");

// Release lock :
flock($fp, 3);
fclose($fp);
0
How to improve team productivity

Quip adds documents, spreadsheets, and tasklists to your Slack experience
- Elevate ideas to Quip docs
- Share Quip docs in Slack
- Get notified of changes to your docs
- Available on iOS/Android/Desktop/Web
- Online/Offline

 

Author Comment

by:gameboss
Comment Utility
to maxkir:
the "flock()" always return true,so the "while()"part of your code always be run.
0
 

Author Comment

by:gameboss
Comment Utility
to maxkir:
the "flock()" always return true,so the "while()"part of your code always be run.
0
 

Author Comment

by:gameboss
Comment Utility
to maxkir:
the "flock()" always return true,so the "while()"part of your code always be run.
0
 
LVL 2

Expert Comment

by:maxkir
Comment Utility
First, it will be run only 10 attempts only if flock returns false.

Second, why it will always return true ? It returns true when it will be able to acquire the lock.

Another way - use semaphores:

$sem = 0x12345;
$sem_id = sem_get($sem);

sem_acquire($sem_id);
$fp = fopen("/tmp/aaa", "w");

for($i=0; $i<100000; $i++)
{
fwrite($fp, "Stuff");
}
 fclose($fp);
sem_release($sem_id);


0
 

Author Comment

by:gameboss
Comment Utility
to maxkir:
I tryed on my computer(windows95).
whatever the file whether be lock,your code always sleep 10 seconds.

0
 
LVL 2

Accepted Solution

by:
maxkir earned 30 total points
Comment Utility
Well, I see. You can't use semaphores.

And i suggest that flock works only on UNIX/WinNT, but I'm not sure.

Well, then use gravities or us111 comments ...
0
 

Author Comment

by:gameboss
Comment Utility
Adjusted points from 10 to 30
0
 

Author Comment

by:gameboss
Comment Utility
thank you very much.
0

Featured Post

How to run any project with ease

Manage projects of all sizes how you want. Great for personal to-do lists, project milestones, team priorities and launch plans.
- Combine task lists, docs, spreadsheets, and chat in one
- View and edit from mobile/offline
- Cut down on emails

Join & Write a Comment

Foreword (July, 2015) Since I first wrote this article, years ago, a great many more people have begun using the internet.  They are coming online from every part of the globe, learning, reading, shopping and spending money at an ever-increasing ra…
This article discusses how to create an extensible mechanism for linked drop downs.
Learn how to match and substitute tagged data using PHP regular expressions. Demonstrated on Windows 7, but also applies to other operating systems. Demonstrated technique applies to PHP (all versions) and Firefox, but very similar techniques will w…
This tutorial will teach you the core code needed to finalize the addition of a watermark to your image. The viewer will use a small PHP class to learn and create a watermark.

763 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

10 Experts available now in Live!

Get 1:1 Help Now