|
|
Sponsored Content
Top Forums
Programming
I have no clue what's the point - fcntl() ?
Post 302075939 by atticus on Wednesday 7th of June 2006 04:47:25 PM
06-07-2006
I have no clue what's the point - fcntl() ?
hi, I need to know how to lock a file. I used the following code, but after executing the program the file 'write.txt' remined empty, and I have no idea why.Maybe I'm not using the corresponding syntax for blocking a file. But I deleted then the blocking part and the problem persisted.
see to code:
......
f=open("read.txt",O_RDONLY);
fcntl(f,F_SETLK);
read(f,buffer,sizeof(buffer));
g=open("write.txt",O_WRONLY);
write(g,buffer,sizeof(buffer));
close(g);
fcntl(f,F_UNLCK);
close(f);
.......
then I tried to replace open with fopen (so I use FILE *g of course, and fprintf()) but still nothing was in that file(write.txt).So I have no clue. If you got sometime pls say somethin'. I need to do this as soon as I can. You are welcomed to say somethin' smart
10x
see to code:
......
f=open("read.txt",O_RDONLY);
fcntl(f,F_SETLK);
read(f,buffer,sizeof(buffer));
g=open("write.txt",O_WRONLY);
write(g,buffer,sizeof(buffer));
close(g);
fcntl(f,F_UNLCK);
close(f);
.......
then I tried to replace open with fopen (so I use FILE *g of course, and fprintf()) but still nothing was in that file(write.txt).So I have no clue. If you got sometime pls say somethin'. I need to do this as soon as I can. You are welcomed to say somethin' smart
10x
Last edited by atticus; 06-07-2006 at 06:40 PM..
|
|
7 More Discussions You Might Find Interesting
1. UNIX for Advanced & Expert Users
Anyone know of a guide or instructions for Solaris
I got to configure a SBUS HBA to talk to a tape robot.
I have done this on a switch but not point to point.
just going HBA >>>>> TAPE Fibre simple two nodes
Kie (6 Replies)
Discussion started by: kie
6 Replies
2. Solaris
df shows that the filesystem is filling up and the usage is 94%.
However when I actually traverse to the directory I du shows only about
10% of the space occupied!
Below is the output of df and du:
>>>df -kh
/cbmdata/00 470M 393M 29M 94% /cbmdata/00
>>>/cbmdata/00>... (3 Replies)
Discussion started by: zombiezparadize
3 Replies
3. Programming
Hi,
Unless I am missing some serious differences in Mac and linux in terms of C programming, I dont know why this would happen. Please take a look at the following piece of code fragment:
bool add_input_to_db(Cons *new_data) {
// Set the attributes of the lock
struct flock fl =... (3 Replies)
Discussion started by: newhere
3 Replies
4. Programming
I have very simple client - server setup, where client connects, exchanges some messages with the server and then closes socket and exits. Everythink works OK, except when I am trying to change socket to be non-blocking AND the shell happens to be plain old Bourne. It runs no problem under ksh or... (3 Replies)
Discussion started by: migurus
3 Replies
5. Shell Programming and Scripting
Hello
I have a Perl script that works on non-darwin Mac OS X environments and I think I have narrowed down the issue to a file locking problem.
In other linux environments, the flock struct is defined differently. I have adjusted this via the reference for Mac OS X fcntl(2) man page. The... (4 Replies)
Discussion started by: flagman5
4 Replies
6. Shell Programming and Scripting
hi,
I would like to ask or is it possible to dump a hex using dd from starting point to end point just like the "xxd -s 512 -l 512 <bin file>"
I know the redirect hexdump -C but i can't figure it out the combination options of dd.
Hope someone can share their knowledge..
Thanks in... (3 Replies)
Discussion started by: jao_madn
3 Replies
7. Linux
Good evening, friends
I'm learning with a book: Programming Linux by Kurt Wall (Prentice Hall)
The code below could run in two windows (./lockit /tmp/foo in both for example). There is not problem with the read block (first byte) but when one, apply the write block while in the other is... (1 Reply)
Discussion started by: joe_cosmo
1 Replies
LEARN ABOUT REDHAT
unix2dos
unix2dos(1) General Commands Manual unix2dos(1) NAME
unix2dos - UNIX to DOS text file format converter SYNOPSYS
unix2dos [options] [-c convmode] [-o file ...] [-n infile outfile ...] Options: [-hkqV] [--help] [--keepdate] [--quiet] [--version] DESCRIPTION
This manual page documents unix2dos, the program that converts text files in UNIX format to DOS format. OPTIONS
The following options are available: -h --help Print online help. -k --keepdate Keep the date stamp of output file same as input file. -q --quiet Quiet mode. Suppress all warning and messages. -V --version Prints version information. -c --convmode convmode Sets conversion mode. Simulates unix2dos under SunOS. -o --oldfile file ... Old file mode. Convert the file and write output to it. The program default to run in this mode. Wildcard names may be used. -n --newfile infile outfile ... New file mode. Convert the infile and write output to outfile. File names must be given in pairs and wildcard names should NOT be used or you WILL lost your files. EXAMPLES
Get input from stdin and write output to stdout. unix2dos Convert and replace a.txt. Convert and replace b.txt. unix2dos a.txt b.txt unix2dos -o a.txt b.txt Convert and replace a.txt in ASCII conversion mode. Convert and replace b.txt in ISO conversion mode. unix2dos a.txt -c iso b.txt unix2dos -c ascii a.txt -c iso b.txt Convert and replace a.txt while keeping original date stamp. unix2dos -k a.txt unix2dos -k -o a.txt Convert a.txt and write to e.txt. unix2dos -n a.txt e.txt Convert a.txt and write to e.txt, keep date stamp of e.txt same as a.txt. unix2dos -k -n a.txt e.txt Convert and replace a.txt. Convert b.txt and write to e.txt. unix2dos a.txt -n b.txt e.txt unix2dos -o a.txt -n b.txt e.txt Convert c.txt and write to e.txt. Convert and replace a.txt. Convert and replace b.txt. Convert d.txt and write to f.txt. unix2dos -n c.txt e.txt -o a.txt b.txt -n d.txt f.txt DIAGNOSTICS
BUGS
The program does not work properly under MSDOS in stdio processing mode. If you know why is that so, please tell me. AUTHOR
Benjamin Lin - ( blin@socs.uts.edu.au ) MISCELLANY
Tested environment: Linux 1.2.0 with GNU C 2.5.8 SunOS 4.1.3 with GNU C 2.6.3 MS-DOS 6.20 with Borland C++ 4.02 Suggestions and bug reports are welcome. SEE ALSO
dos2unix(1) 1995.03.31 unix2dos v2.2 unix2dos(1)