Write in file problem

My problem is:
I wanna write in a file. But what happen if another application is writing in that file in the same time?
Is it possiple to check if anyone is writing in this file or what can i do not to get in a write conflict?
I use the class FileOutputStream to write in the file.

It is the job of the operating system to make sure that two applications don't write to the same file at once.
Bascially, you don't need to worry about this at all, it is handled automatically by Windows/linux etc for you.

Similar Messages

Time stamp data write to file problem

Hello!
I'm just learning LabView, and have arrived at the stage of writing time-stamped data to text files.
This seems clear enough, however when I examine the file written to disk, I find 4 unexpected characters: 3 spaces and one seemingly random number or punctuation mark, preceding every line!
An example is:
   .2005-07-15 10:55:40.0 the value is 0.0000 cm
   .2005-07-15 10:55:40.5 the value is 1.0000 cm
The four characters "   ." are those whose origin I can't understand. I can't seem to get rid of them.
They seem to change with the input string, but not in a manner I can predict or understand.
Any hints or explanations would be greatly appreciated, as I'm at wit's end after 1/2 day of puzzling over this little problem!
Alex
Attachments:
time stamp data write VIs.zip ‏24 KB

Alex,
You found one of the subtle little things that can be frustrating to old-timers and newcomers alike. I did not recognize it until I read the help file (and I have been using LV since version 1.2).
First, the three characters before the commas are nulls (\00).
The reason they are there is in the help file for the Write File.vi. By wiring an array to the data input, you caused the VI to write a header telling what data format was used.
I modified your VI to simply concatenate the strings and then write a simple string to the file. I think this may be what you were after.
Lynn
Attachments:
write timestamp text line to file v3.vi ‏47 KB

Xcode writting/reading file problem

Hi,
im using xcode to compile in c language, but im having problem with files, writting/reading simply doesnt work (to be exact i have to say that i copied source code to dev-c++ on windows platform to check the code and it works normaly as it should) any suggestions?
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int main (int argc, const char * argv[])
char tekst[]="tujesttekstktorychchcezapisacdopliku";
          char tekst2[20];
FILE *plik;   /*r=read, w=write, rwx-obydwachyba, wb-tryb binarny*/
          if ((plik=fopen("text", "w"))==NULL)
printf("plik nie zostal otworzony");
          fprintf(plik, "%s" ,tekst); /*wpisanie tekstu*/
          fscanf(plik, "%s",tekst2);
printf("tekst2: %s\n", tekst2);
          if (fclose(plik)!=0)
printf("blad przy zamykaniu");
    printf("Hello, World!\n");
    return 0;
the result of this program is "hello world" ONLY.
file is clean, same thing with test2 variable.
in copied code opening mode is "w" but ive checked almost all options ofc including binary file modes (both doesnt work)
any suggestions?
Message was edited by: Entwu

while( (len = in2.read(b,0,1024)) != -1 )
bytcount=bytcount+1024;
inFile.write(b,0,1024);
} This is where you go wrong ... suppose you're reading, say 100 bytes instead of the maximum 1024;
you're still writing 1024 bytes instead of those 100 bytes; your 'bytcount' goes berzerk too. Have a
look at this -- while( (len = in2.read(b,0,1024)) != -1 ) {
   bytcount=bytcount+len;
   inFile.write(b,0,len);
} kind regards,
Jos

FileWriter Problem, cannot write a file larger than 8K

Hi,
My servlet write 2 files. The problem is the second file I wrote cannot exceed 8K
PrintWriter os = new PrintWriter(new FileWriter("temp\\q0.dat"));
os.close();
PrintWriter os2 = new PrintWriter(new FileWriter("temp\\q1.html"));
I have the following write statement:
os2.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0 Transitional//EN\">");
os2.println("<HTML><HEAD><TITLE> Q1 </TITLE>");
os2.println("</HEAD><BODY><FORM METHOD=POST ACTION=\"\"><BLOCKQUOTE><TABLE border=\"0\">");
The problem is if I use this kind of statement, some println statement not appear in the destination file q1.html (those lines at bottom)
then if I turn these 3 statement and change to 1 print statement, more letter write to q1.html?
Pls tell me what's wrong with my program! Thank you

You didn't close the second PrintWriter after you finished using it?

Write file problem

Hi, guys
I have a problem to write a file using PrintWriter. What I want to do is my program takes file name and path, if the same name file exist in the folder, data ppended at the end of the existing file, otherwise it generates the new file.
File file_out = new File(path, title);
       //System.out.println(file_out.getName());
       if (fileName_out.getName().equals(""))
         JOptionPane.showMessageDialog(this,"Invalid File name",
               "Invalid File nmae",JOptionPane.ERROR_MESSAGE);
         return(false);
     else
               try
                    boolean created = file_out.createNewFile();
                    if(created)
                        fileOutput = new PrintWriter(new FileWriter(fileName_out));
                        return(true);
                    else
                        fileOutput = new PrintWriter(new FileWriter(fileName_out,true));
                        fileOutput.println("File Name"+"\t"+"Slope(m)"+"\t"+"y-intercept(b)"+"\t"+"Correlation(r)");
                        return(true);
                catch (IOException exc)
                     System.err.println("Can not open the file " );
                     return(false);
                }I don't know what's wrong with, when I run this program, it doesn't make any file and issues NullPointerException.
Anybody got solutions?
Thanks a lot,

File file_out = new File(path, title);
       //System.out.println(file_out.getName());
       if (fileName_out.getName().equals("")) Is there a reason why you assign something to the variable file_out and then start working with a different variable fileName_out? Which you probably haven't assigned anything to, leading to NullPointerExceptions?

Write to text file problem

I have a write to 'text file' in a sub vi. It is a popup where user can change his program.
For some reason, only the first time it is called, it actually writes to the text file.
As long as the sub vi is in memory, and I call it again and press ok to write to text file, nothing happens.
I've tried 'close file', but that doesnt help. Deleting the files from the disk before again calling the sub vi doesnt help either, it wont write
to file again. Is this a bug or am I missing something?! Im on labview 2010

Post your VI (along with sub-VI's if any).
I am not allergic to Kudos, in fact I love Kudos.
Make your LabVIEW experience more CONVENIENT.

Can't read or write some files, internet is failing, youtube won't load, software I tried to install was in Slovenian, not dutch or english like in my systempreferences settings, pictures and files won't preview with spacebar, etc. Malware?

Specs:
iMac 10.8.5
3,4 GHz Intel Core i7
32 GB 1600 MHz DDR3
Can't read or write some files, internet is failing, youtube won't load, security software I tried to install was in Slovenian, not dutch or english like in my systempreferences settings, pictures and files won't preview with spacebar and are randomly corrupted, when I entered something in the Youtube searchbar (when it was still working) it send me to a site with sexadds.
I tried restart my iMac and when I was logged back in, my dock preferences were reset.
Also tried to download some security software to check my Mac for malware, but when I did, I tried several, I got a notification that said something like 'dumpfiles (don't know if this is the right translation...) damaged'.
I'm taking screenshots from all the weird notifications I get and even three quarters off the screenshots I took in the last three hours are already unreadable.
It started this morning when I tried opening a Premiere Pro file on which I worked the night before.
When I tried opening it, it said the file was damaged and could not be openend.
I tried opening it with AE or importing the file in a new project but nothing helped.
When I tried looking for autosaves, this is the really weird part, there were none.
Even though there are autosaves from my other projects, this one was completely gone.
It looked like the day before never happened on my computer.
Also when I openend Premiere all the recent projects had been wiped.
So at first I thought it was a Premiere Pro failure.
But than, later on the day, I tried loading some RAW files from my compact flash card.
This is where I would get an error (error -36) which said some data cannot be read or written.
I tried importing the files with a view different technics, from dragging to importing via Lightroom and I succeeded with Image Browser.
But when I tried moving the files to an other folder the same error occurred.
While dealing with this issue I wanted to put on some soothing music on youtube.
This is when the next weird thing occurred: youtube wasn't completely loading in Chrome. I refreshed a view times, checked the internet connection and still no difference.
When I tried in Safari it did work but when I clicked enter on the searchbar in Youtube, a page with sexadds appeared (I didn't install AdBlock in Safari...).
I read about this 'phishing' where you are redirected to a site were a possible malware installment can take place...
I don't know if it's connected to any of the problems I've been having but I just never experienced this on a mac, I have been a Mac user for 10 years now.
On top of it all, internet started working worse and worse and now it's not even working at all. I had to fill in the password over and over, normally it remembers.
Just like my system preferences, all the preferences I had with Chrome where also reset.
Also somewhere in between I got this notification: Mac OS X must restore library to run programs. Type your password to allow.
To me this is all very weird and suspicious. I have clearly no idea what's going on. Could this be another sort of trojan horse or malware?
Some background info which could be helpful for solving this mystery:
two months ago the one year old Fusion Drive in my iMac just broke out of nowhere.
I got it replaced by a qualified apple repair store.
When I got my computer back, all the files where gone.
I got on the internet without AdBlock installed yet.
A game or whatever it was, can't clearly remember, got installed by accident.
I deleted it immediately.
Only two weeks later, I couldn't log in to my account. It didn't recognize my password and username.
So I brought my mac back to the store.
Here the repair guy said it was a minor thing and he just needed to reconnect my account. He also mentioned he found a downloaded game name Sparta and it probably had something to do with the error.
I asked him; could it be a virus? He replied no way.
I don't know why I couldn't be a virus, just because it's a mac doesn't mean it cannot be done.
So today I tried installing anti virus software (such as avast- was in a weird language looked like slovenian, clamxav - was in slovenian) but I couldn't install them.
PLEASE help me! I don't know what to do anymore, I work fulltime and I need my computer, I have no time to bring it in for repair, are there other perhaps easier ways?
Could this be the work of a virus or a malware? Or is it a disk permissions issue?

It sounds like you may have multiple problems, but none of them are likely to be caused by malware.
First, the internet-related issues may be related to adware or a network compromise. I tend to lean more towards the latter, based on your description of the problem. See:
http://www.adwaremedic.com/kb/baddns.php
http://www.adwaremedic.com/kb/hackedrouter.php
If investigation shows that this is not a network-specific issue, then it's probably adware. See my Adware Removal Guide for help finding and removing it. Note that you mention AdBlock as if it should have prevented this, but it's important to understand that ad blockers do not protect you against adware in any way. Neither would any kind of anti-virus software, which often doesn't detect adware.
As for the other issues, it sounds like you've got some serious corruption. I would be inclined to say it sounds like a failing drive, except it sounds like you just got it replaced. How did you get all your files back after the new drive was installed?
(Fair disclosure: I may receive compensation from links to my sites, TheSafeMac.com and AdwareMedic.com, in the form of buttons allowing for donations. Donations are not required to use my site or software.)

Write to file(AVI) synchronizate data

I receive a USB Camera signal and a CAN(Control Area Network) signal.
I like two signal parallel displaying and write to file (one or more) and after read.
I practise IMAQ AVI Write Frame.vi with DATA.
I receive USB Camera signal around 15fps (but this is not constant). Two CAN messages receive 10ms/sec.
(200 CAN messages per sec -> 1camera signal/14 messages: I make a queue. When receive a Camera signal, than in all queue data associated with the image to write).
I make two loop:
First: read USB Camera and save AVI with data
Second: read CAN messages
My problem is bottleneck CAN bus?
(webcam_can2.vi)
Attachments:
CAN_AVI.llb ‏465 KB

Hi
For the VI in the attachment (from the CAN_AVI.llb) the
problematic part is the " call library function node" which is defined
as the wecanusb.dll.
What should be done ? How the input
parameters should be processed to be outputted by the " call library
function node" block ?
thank you..
Message Edited by HIDIR on 04-23-2009 03:43 PM
Message Edited by HIDIR on 04-23-2009 03:44 PM
Message Edited by HIDIR on 04-23-2009 03:47 PM
Attachments:
examine.doc ‏56 KB

Lion server file sharing issue with windows API read/write ini file (GetPrivateProfileString)

Hello,
I try to config lion server as file server for a windows application we use at work. All other computers are windows 7 or XP, lion server is the only mac. I choose lion server because it's size, quality and personal love of apple products.
10.7.2 lion server's samba file sharing works almost perfectly with all my windows machines, I can copy, delete, modify any text files or office files without any issue, but the most important windows application for my business doesn't work with samba file sharing. After some digging, I found it is because windows program can't read or write INI file stored on lion share. Windows API GetPrivateProfileString always returns empty if the INI file is store on lion share.
You can download a small application for read/write windows INI file from codeproject.com to test this problem:
http://www.codeproject.com/KB/files/ini.aspx
I can open/edit the in file using any text editor without any problem. The only problem is with those windows APIs. ACL is turned on for my lion share and assigned "delete" rights to samba users.
I install samba3 on the same server; it works perfectly with windows API. My windows program also works. Looks like there is something wrong with lion server's sambax.
I'd prefer to use built-in samba even I have samba3 working. Built-in samba is very immature right now, but considered how young it is, I will give apple some time to make it mature.
Does anyone have same issue or knows how to fix it?
Thanks,
Michael.

All the memory is fine. The server rarely if ever goes down when there are only around 10-12 users connected. When there are 20+ users connected and working heavily it goes down often. When I say working heavily, I mean they are transferring huge files to the SAN (100GB+), sometimes 5 at a time per user, and there are a bunch of others who are reading large video files at a minimum of 220MB/sec from the SAN.
Though this worked on Snow Leopard without any issues, Lion just doesn't seem to be able to handle it. The odd thing is, on Snow Leopard there was only a single 1GB ethernet connection to a NAS system, whereas with Lion we have a much more powerful machine with a 6-port 10GB ethernet card and a 4 lane 8GB fiber card to a true SAN. You would think that the newer scenario with Lion would handle far more users with ease.
So far, very disappointing with regards to Lion's file serving performance.

Airport Extreme, Airdisk, and Vista - large file problem with a twist

Hi all,
I'm having a problem moving large-ish files to an external drive attached to my Airport Extreme SOMETIMES. Let me explain.
My system - Macbook Pro, 4gb ram, 10gb free HD space on macbook, running latest updates for mac and vista, external hard drive on AE is an internal WD in an enclosure w/ 25gb free (its formatted for pc, but I've used it directly connected to multiple computers, mac and pc, without fail), AE is using firmware 7.3.2, and im only allowing 802.11n. The problem occurs on the Vista side - havent checked the mac side yet.
The Good - I have bit torrents set up, using utorrent, to automatically copy files over to my airdisk once they've completed. This works flawlessly. If i connect the hard drive directly to my laptop (macbook running bootcamp w/ vista, all updates applied), large files copy over without a hitch as well.
The Bad - For the past couple weeks (could be longer, but I've just noticed it recently being a problem - is that a firmware problem clue?) If i download the files to my Vista desktop and copy them over manually, the copy just sits for a while and eventually fails with a "try again" error. If i try to copy any file over 300mb, the same error occurs.
What I've tried - well, not a lot. The first thing i did was to make sure my hard drive was error free, and worked when physically connected - it is and it did. I've read a few posts about formatting the drive for mac, but this really isnt a good option for me since all of my music is on this drive, and itunes pulls from it (which also works without a problem). I do however get the hang in itunes if i try to import large files (movies). I've also read about trying to go back to an earlier AE firmware, but the posts were outdated. I can try the mac side and see if large files move over, but again, i prefer to do this in windows vista.
this is my first post, so im sure im leaving out vital info. If anyone wants to take a stab at helping, I'd love to discuss. Thanks in advance.

Hello,
Just noticed the other day that I am having the same problem. I have two Vista machines attached to TC w/ a Western Digital 500 gig USB'd. I can write to the TC (any file size) with no problem, however I cannot write larger files to my attached WD drive. I can write smaller folders of music and such, but I cannot back up larger video files. Yet, if I directly attach the drive to my laptop I can copy over the files, no problem. I could not find any setting in the Airport Utility with regards to file size limits or anything of the like. Any help on this would be much appreciated.

Error writting to file:

Error writting to file:
C:\Config.Msi\e0cc87.rbf. Verify that you have access to that directory

I had this exact same problem just now, trying to upgrade to 10.7.
I even got that error msg when trying to UNINSTALL iTunes!
After hours of frustration trying everyone's different suggestions, I downloaded Revo Uninstaller http://www.cnet.com.au/apps/revo-uninstaller-10610875/ which solved the problem.
Use it to help uninstall iTunes and related software components in the following order and then restart your computer:
iTunes
QuickTime
Apple Software Update
Apple Mobile Device Support
Bonjour
Apple Application Support (iTunes 9 or later)
Then you can install iTunes from scratch.
Good luck

Write to file taking too long.

Hi,
I have a peculiar problem . I have used state machine architecture to build my code. In one particular state i write the data accquired and strore the wave form graphs as jpegs on the disk.
File open and close happen only once outside the while loop. I am using "Write FIle" vi to write the data. Data is first bundled into a cluster and then writte. I use "Write JPEG FIle" to store graphs as JPEGS.
When i create the executable and run, the program stops here in this state for an indefinite amount of time. (sometimes 60 secs, 80 secs)
and then continues. Multiple tests have confirem that the problem is either due to file write or JPEG write.
Can anyone please tell me the cause of error
what happens to all the pop ups (errors thrown by labview when running the program) when the program is converted ino an executable?
Rgds
Prithvi.

Hi prithvi,
I suppose you work on a windows system. Windows may buffer the contents of a folder to allow faster directory queries. So sometimes your access is granted very fast,
sometimes not (= getting new directory listing)...
It's always a good idea to have a well structured folder tree for your files. Why don't you use subfolders for each measurement? Why don't you use a subfolder for each new day/hour, depending of the number of measurements done it that time?
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome

Bug in writing Integer Data in Hex in Write Spreadsheet File

It appears that Write to Spreadsheet File forces all data to I64. Try writing an I16 or I32 array with a negative number. Format specification to 4x, 8x or whatever is ignored and you get a full completent of 16 bytes with a lot of FF's at the beginning making it I64
Chief Scientific Officer & Ex-Head
Advanced Centre for Materials Science
Indian Institute of Technology
Kanpur 208016
Phones: +91-512-2597830, 3927830(Off), 2574628 (Res), 9336117477 (Mob)
Fax: +91-512-2597459
E-mail: [email protected], [email protected], http://home.iitk.ac.in/~sg

Hi;
it's not a bug it's a feature :-)
Whenever you want to format numbers the formatting routine will try to leave as much digits as needed/possible. When you format I8 then 2 digits are ok, I16 needs 4 digits and so on.
You can easily test this behaviour when using the 'Array to spreadsheet string' function (it's also used inside 'Write spreadsheet file'). When saving negative integers as Hex formatted ALL digits are needed to describe the number and so you get all of them in your text file!
The only problem is: 'Write to spreadsheet file' only knows about I64. Whenever you want to save negative numbers you get 16 digits regardless of format string.
Solution:
Change the 'write to spreadsheet file' as described before or do the formatting on your own by using 'array to spreadsheet string'!
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome

File Read and Write using File Adapter in Bpel

In Bpel Process i am using File Adapter ( Schema is Opaque) for read and write the file contents. i am able do successful deployment and read, write function in first time deployment, after that again i tired to run the application, its not going to write the content of file, its only writing the file with out data's or content in that file.
Please help me...
Saravanan

Hi Eric
In my domain.log file having the following details. In this file im unable to find out what the exact problem. Please look at this and help me.
<2008-01-22 18:25:42,024> <INFO> <default.collaxa.cube.compiler> validating "C:\product\10.1.3.1\OracleAS_1\bpel\domains\default\tmp\.bpel_BPELProcess2_1.1_298e83988d77b6640c33dfeec11ed31b.tmp\BPELProcess2.bpel" ...
<2008-01-22 18:25:49,850> <INFO> <default.collaxa.cube.engine.deployment> <CubeProcessFactory::generateProcessClass>
Process "BPELProcess2" (revision "1.1") successfully compiled.
<2008-01-22 18:25:49,914> <INFO> <default.collaxa.cube.activation> <AdapterFramework::Inbound> Loading JCAActivationAgent for {portType=Read_ptt}
<2008-01-22 18:25:49,914> <INFO> <default.collaxa.cube.activation> <AdapterFramework::Inbound> JCAActivationAgent::load - Locating Adapter Framework instance: OraBPEL
<2008-01-22 18:25:49,930> <INFO> <default.collaxa.cube.activation> <AdapterFramework::Inbound> JCAActivationAgent::load - Done loading JCAActivationAgent for processId='bpel://localhost/default/BPELProcess2~1.1/
<2008-01-22 18:25:49,930> <INFO> <default.collaxa.cube.engine.deployment> Process "BPELProcess2" (revision "1.1") successfully loaded.
<2008-01-22 18:26:02,698> <INFO> <default.collaxa.cube.activation> <AdapterFramework::Inbound> JCAActivationAgent::uninit Shutting down the JCA activation agent, processId='bpel://localhost/default/BPELProcess2~1.0/', activation properties={portType=Read_ptt}
<2008-01-22 18:26:02,698> <INFO> <default.collaxa.cube.activation> <AdapterFramework::Inbound> Adapter Framework instance: OraBPEL - performing endpointDeactivation for portType=Read_ptt, operation=Read
<2008-01-22 18:26:02,698> <INFO> <default.collaxa.cube.ws> <File Adapter::Outbound> Endpoint De-activation called in adapter for endpoint : D:\MAXIMUS_Project_Softwares\jdevstudiobase10132\jdev\mywork\MyLabs\BPELProcess2\in
<2008-01-22 18:26:02,698> <INFO> <default.collaxa.cube.activation> <AdapterFramework::Inbound> JCAActivationAgent::init - Initializing the JCA activation agent, processId='bpel://localhost/default/BPELProcess2~1.1/
<2008-01-22 18:26:02,698> <INFO> <default.collaxa.cube.activation> <AdapterFramework::Inbound> JCAActivationAgent::initiateInboundJcaEndpoint - Creating and initializing inbound JCA endpoint for:
process='bpel://localhost/default/BPELProcess2~1.1/'
domain='default'
WSDL location='rd.wsdl'
portType='Read_ptt'
operation='Read'
activation properties={portType=Read_ptt}
<2008-01-22 18:26:02,698> <INFO> <default.collaxa.cube.activation> <AdapterFramework::Inbound> Adapter Framework instance: OraBPEL - endpointActivation for portType=Read_ptt, operation=Read
<2008-01-22 18:26:02,730> <INFO> <default.collaxa.cube.activation> <File Adapter::Inbound> Endpoint Activation called in File Adapter for endpoint: D:\MAXIMUS_Project_Softwares\jdevstudiobase10132\jdev\mywork\MyLabs\BPELProcess2\in
<2008-01-22 18:26:02,730> <INFO> <default.collaxa.cube.activation> <AdapterFramework::Inbound> Adapter Framework instance: OraBPEL - successfully completed endpointActivation for portType=Read_ptt, operation=Read
<2008-01-22 18:26:02,890> <WARN> <default.collaxa.cube.activation> <File Adapter::Inbound> PollWork::run exiting, Worker thread will die
<2008-01-22 18:26:04,171> <INFO> <default.collaxa.cube.ws> <File Adapter::Outbound> Managed Connection Created
<2008-01-22 18:26:04,171> <INFO> <default.collaxa.cube.ws> <File Adapter::Outbound> Connection Created
<2008-01-22 18:26:04,171> <INFO> <default.collaxa.cube.ws> <File Adapter::Outbound> FileInteraction Created

How can I write a file and fill it in periods?

Hi Every body!
I need help with this.
I have my aplication(power quality analiser),This VI obtain several varibles and make a lot of calculus and operation, to obtein others parameters in real time so my problem is Save the acquire data and calculus data into a file (similar as a report) every period(custumizable for the user in time units)
I mean make a only one file wich is write every period continuously , e.g. Start my principal VI and this event start the write of file, past one period,make other row or colum into the same file and continue that way until we stop the principal VI.
How can I make that?
Thaks very much
Best Regards

Hi,
assuming you have your trigger (notifier or just periodically) you can append the data to a single record.
Open the file, set the file position to the end, write the data and close the file.
Hope this helps

Write in file problem

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