Trying to empty file using > but the file size increasing when next append

Thread Tools Search this Thread
Top Forums UNIX for Dummies Questions & Answers Trying to empty file using > but the file size increasing when next append
# 1  
Old 06-23-2008
Trying to empty file using > but the file size increasing when next append

AIX 5.3 / KSH

I have a Java application which creates a log file a.log. I have a KSH script which does the following action

cp a.log /directory2/b.log
> a.log

After this the file size goes to 0 as per "ls -l"

Then next time when the application writes into this file, the file size is goes to the previous before the ">" operation happened.

I tried the Code in a different style:
cp a.log /directory2/b.log
cp /dev/null a.log

No change. What is the best way to do this?

***NOTE: I cannot use rm -f/touch method for cleaning up the log file because it requires a restart of the application.
# 2  
Old 06-23-2008
Yes, some applications are written like that and if you can't stop the appl. for wrapping the log, you will have to expand the FS, if possible... or persuade people of a short downtime of some minutes once per week at night per cron to clean up and wrap.
# 3  
Old 06-23-2008
Thanks for response.

Expand FS means increasing the size of the mount?

Any idea why the log file size becomes 0 immediately I executed ">" operation ($ > a.log) and the file size resets to earlier size (some 100MB) immediately after the first byte written into the log file?

I cannot both rely on removing the file or expanding the file. The only solution I can go for is a safe cleanup of this file, without removing or renaming.

Appreciate your thoughts.
# 4  
Old 06-23-2008
I think it is exact the same size like before after you nulled it, because it is maybe cached by the appl. or something like that. Seems it accepts the writing 1st, but a file handle appears to be still open on that file that revokes the former action somehow. I am no programmer, maybe someone else can explain it in detail.

Expand FS means increasing the size of the mount?
Yes, if that's an option for you. The appl. might crash, spit errors or something like that if it runs out of space anyway.

I cannot both rely on removing the file or expanding the file. The only solution I can go for is a safe cleanup of this file, without removing or renaming.
You misunderstood me. When you are allowed to get a short downtime maybe once a week, depending on how fast the log is growing, or once per night, whatever, you stop the application graceful, cp that file to a.log.`date %+w` for example, compress it and just null the original like you tried already "> a.log". When your log files are set, start your appl. again.
Write a little script for this and put it as a cronjob - done.
# 5  
Old 06-23-2008
Thanks for the points and really good. I think I need to go back to Application Developers to see if they can rotate the logs cleanly...

The approach you had mentioned (using the crontab) is already in place, except that the application restart.

Thank you so much for your help... Smilie

Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Emergency UNIX and Linux Support

Script to fill the file system mount with empty files to desired size

We are regularly using for our testing, where we are manually filling up the mount with desired size with following command dd if=/dev/zero of=file_2GB bs=2048000 count=2000 We are planning to automate the task where taking input for % of size as one input and the name of the file system... (8 Replies)
Discussion started by: chandu123
8 Replies

2. Solaris

Help with increasing file system size in Sun OS 5.9

Hi, I have recently taken up to support these SunOS 5.9 sun4u sparc SUNW,Sun-Fire-V240 boxes and got a request to increase the size of /backup01 as its getting filled up quickly and can't play much on it as these are production servers. As I have no idea about how to do this, can anyone let me... (0 Replies)
Discussion started by: phanidhar6039
0 Replies

3. Shell Programming and Scripting

Symbolic link to an empty file shows size 2

Hi, I have created an empty file and a symbolic link to a file. But when I issue the following commands, I am getting the output 2. stat -c "%s" linkfile du -hb linkfile Why this is happening? (4 Replies)
Discussion started by: royalibrahim
4 Replies

4. Shell Programming and Scripting

if file is NOT empty, then append content to file

hi people, i have texts down.txt and down-new.txt and i want to check; - if down-new.txt is NOT empty, then write date and its content to /home/gc_sw/down.txt for example; down.txt:AAAA SSSS down-new.txt:123 456 and after checking down-new.txt is NOT empty, down.txt should... (10 Replies)
Discussion started by: gc_sw
10 Replies

5. Linux

Increasing total data size per file system request for block drivers

Hi All, I am writing a block driver for a 2GB SD card where i get the total amount of data per request as follows: struct request *req; uint card_addr,total_bytes; struct request_queue *rq = BlkDev->queue; req = elv_next_request(rq); .. .. card_addr = req->sector*512;... (1 Reply)
Discussion started by: amio
1 Replies

6. Shell Programming and Scripting

Unix file empty.. but size is greater than zero??/

Hi, I have a file by redirecting some contents in unix shell. Even when there is no content that is being redirected, the file size still shows greater than zero. but even if there is no matching pattern the file APPRES has size greater than 0bytes. awk -f AA.awk $logfile>APPRES... (3 Replies)
Discussion started by: justchill
3 Replies

7. Solaris

increasing file system size

Hi Can anyone explain me how to increase the filesystem size. We can do it when the system is running? It needs an reboot? (8 Replies)
Discussion started by: rogerben
8 Replies

8. HP-UX

Help on increasing fs size

Hi Experts, I am not sure whether my question should be in this thread or some other one. I am using HP Tru64 system. Currently one of my filesystem /others is almost full. I need to know the exact commands to increase this filesystem. Please show me how to check for free partitions and add... (5 Replies)
Discussion started by: kingsto88
5 Replies

9. AIX

Increasing File Size on AIX

Hi I am a bit green to AIX - but when our backup operator tries to do a restore from one AIX box to another, he get's the error: 'A file cannot be larger than the value set by ulimit' I am wondering what is the impact of increasing the AIX filesize limit of 2 gb to unlimited. And how would... (1 Reply)
Discussion started by: Rosie C
1 Replies

10. UNIX for Dummies Questions & Answers

increasing ufs file system size in solaris

How do i increase the filesystem size on a root partition? There is a slice with root on it, its like 2 gigs and nothing else is broken out except home. I want to increase root filesystem (and slice) and break out /usr and /var. This is solaris 9, only has solaris volume manager on it. ... (6 Replies)
Discussion started by: BG_JrAdmin
6 Replies
Login or Register to Ask a Question

Featured Tech Videos