I am going to write a TCP server program using c. Can anyone give me some advices on whats and what not to do specially when using select?
There would be a lot of data to be transferred both on the server and back to the client. I already have a simple server here but the server uses a lot of resources. Maybe 3 to 4 connections and the server's load would rise to unacceptable levels.
Which do you think is better to use fork or select?
I am writing a script to do a speed measurement from my ISP's test ftp server. To do this interactively I connect to the server, enter credentials, enable hash and download a test file. The process concludes with something like
Quote:
################################################################
226 Transfer complete.
1048576 bytes received in 2.87 secs (356.6 kB/s)
So I entered the credentials for the server in my .netrc file and created a little bash script as follows
Quote:
#!/bin/bash
cd ~/Desktop
# poiuytrewq is the limit string of the "here" document
[code]...
The script executes as expected EXCEPT that I do not see the statistics at the end of the transfer. It terminates thusly
Quote:
#################################################################################################### ############################################
ken@taylor12:~/Desktop$
I have tried adding another ftp command such as ls to the end of the "here" document (in case the results were clipped by the bye command) but to no avail. The ls result immediately follows the ### - no stats I am at a loss.
I want to write some PHP for a website that'll have the data that the script will generate written inside a table with thin black line around it, much like LQ itself. My problem is: how do I draw the box that the text will be inside of, since the amount of text will vary - if I have a GIF with a picture of a box, that'll be of a fixed length, and my script can then only generate that much text, for it to look nice. Or do I need to fiddle with the GD library to get done what I want?
View 4 Replies View RelatedSo basically, there is a really cool writing system I have been working on. It could be viewed (for simplification purposes) like an encryption method for the Latin script.
Facts about the writing system:
It has a little over 300 symbols.
It is syllable-driven.
It is highly compositional (eg. "c", "ca", "cae", "ca " and "ci." all map to different symbols - and NOT by overlaying elements)
Symbols have medium graphical complexity (comparable to Korean Hangul, or Japanese Hiragana)
Has a rather complex set of diacritics (~10, some of which can go on any symbol)
Has no ligatures
How transliteration occurs:
Sequences of Latin symbols map to certain symbols. Example below:[G][rou][p ][hu][g.]Characters sequences between "[" and "]" map to a single symbol (so it would take only 5 symbols to write "Group hug.").
How I want it to work:
I would like to have a daemon that: Intercepts all text displayed on the screen.
Converts it to my writing system (changes letter sequences with individual Unicode codes)
Leaves unsupported symbols unchanged.
Displays all the text on the screen using my font and characters intertwined with the fonts and characters left unchanged.
For example, if you take the following line of C++ code:for (i = 1; i <= n; i++)
I would like it displayed like this:[fo][r ]([i ]= [1]; [i ]<= [n]; [i]++)
Bold-symbols should be in my Unicode font with special symbols defined for this writing system, and the rest should be in its original font and encoding. Also, I would like this encoding to hold for display-purposes only. The data in the memory should remain unaffected. This also means real-time adjustments: if I open a text editor (say, from the OpenOffice Suite) and I start typing, I would like to see what I type encoded with my writing system, even though the document actually contains Latin letters. This also means that the symbol immediately before the cursor may change as you type.
I have written a daemon server. I would like to add the ability for the daemon to update itself. That is, it should be able to download the latest version of the code (when it receives a signal from a client) and then restart itself. I am stuck on getting the daemon to restart itself. The problem is killing the old daemon without killing the process that is starting the new daemon. In my latest attempt, the daemon that is updating itself runs a program in a subshell (using system) that starts a restarter daemon that runs the original daemon (again using system) with the restart command option. With the restart option, the new version of the daemon sends a terminate signal to the old version. Obviously, when I run the original daemon manually with the restart option, it restarts reliably. I figured that issuing the same restart command from a daemon would adequately isolate the process doing the restarting from the program being restarted. Using ps, I can see that the daemon does actually restart. However, the client locks. In fact, a few times, the OS locked and I had to reset.
View 7 Replies View RelatedHow to write a mkdir with -p option. I am struggling for creating subfolders. the chdir() is not working and thus subdirectories can't be created.
Code:
I'm not able to write to a file using my perl cgi script which is as fallows:
Code:
#!/usr/bin/perl -w
use strict;
print "Content-type: text/html
[Code]....
I am trying to write .pgm images using the O_DIRECT flag in open().I have a char* buffer which has the image data. I know that I have to align the buffers and have done that using posix_memalign() yet only a part of the image gets written.Has someone used O_DIRECT for writing files successfully?
View 1 Replies View RelatedI'm trying to write a simple, console based application in linux, in c++. I know how to start in Eclipse and I have some experience in c++ from Windoze. I would like to ask, if there is some tutorial available on writing console apps. I mean, I know from using linux that there are two conventions on using parameters in command line (-v and --version for example).
View 2 Replies View RelatedMy platform is linux Centos 5. I have read that to learn programming is to read well-written code and take some project to work with. I am always fascinated by routers and firewalls. Like pfsense and vyatta. May be my searching skills are worst but i am not able to find any good tutorials. Ofcourse i dont expect anyone to write a complete router on their blog but wasnt even close to it.
View 1 Replies View RelatedI am running a java application on centos. For now I have a gsm modem connected via the the usb cable. Below is the message I get when I type the command dmesg | grep tty
serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
00:0c: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
usb 2-2: pl2303 converter now attached to ttyUSB0
[code]....
Code:
int main ()
{
[code]...
I have assignment to write bash script and I have to submit it after tommorow . I do not have experience to finish it by myself.I am really need help if any one can contact me. on my email I will be thanks him/ her.
View 14 Replies View RelatedReading and writing text files in C?
View 9 Replies View RelatedI would like to write a program that can read every ethernet frame arriving on a specific hardware NIC, without a TCP/IP stack otherwise doing anything on that NIC. Likewise I want to be able to write out to that NIC. So every arriving ethernet frame, of all types, would be readable (probably one at a time to preserve frame boundaries). And every write of exactly that same data would send frames out. The data read and written would be the whole ethernet frame. The kernel would do nothing else with this data, but other NICs would still operate as usual.
What I would be doing is that on 2 separate NICs, copying frames from one to the other, as in bridging. But I would also be doing modifications per what my program needs to do (not at liberty to say what that would be). What facility would I need to be looking at to do this? There is no ethernet device file. Would raw sockets be able to do this? The programming language will be C.
I created a small C++ program which starts a server in a separate thread and waits the user to press q using the standard input/output. Something like:
Code:
printf(...);
server->Start();
[code]....
I am trying to learn how to write a kernel module. I am following the excellent guide from The Linux Documentation Project called The Linux Kernel Module Programming Guide v.2.6.4.
My machine is running Ubuntu Lucid Lynx (10.04)
Code:
I installed the corresponding linux headers and just to make sure I also installed the linux source and extracted it in /usr/src
I am trying to run the following trivial kernel module
Code:
I just want to read and write some values (integer) to my driver. I used put/get user but always getting errors.
driver
Quote:
int Wert;
static int device_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsinged long arg)
int ret;
[code]...
Quote:
int WERT
ret=ioctl(fd, SETIT, WERT)
ret=ioctl(fd, GETIT, WERT)
if i say in C++ WERT is 5 the value arg of the driver becomes 5 but not WERT the returnvalue of get and put user is -1 so it failed.
I'm currently doing a tutorial for writing kernel modules. Right now I'm still at the very beginning, i.e. writing my helloworld stuff.
But what I like to do now is to write stuff onto the console, and I don't get it. According to my tutorials I can print stuff on the console using the printk()-function as long as the priority-level of the macro used in printk() is lower than the console_loglevel (how can I find that value out btw?).
But it doesn't work for me. Even if I use KERN_EMERG it still gets only logged, but not printed on the console and I thought KERN_EMERG get always printed...
Here's my code:
Code:
Code:
Everything works fine. But as soon as there are any blanks in mystring, e.g.
Code:
I always get
Code:
Why do I get this error and how can I insert string with blanks?
I want to write data to serial port ( ttyS ) from inside the kernel.
View 5 Replies View RelatedDoes anyone have some material about statistics using ubuntu / linux server, or a text which generally describes the ubuntu server?I need urgent, i'm writing specialization work about administration apache and ftp server on ubuntu 10:10 server, so I need something for the conclusion.
View 7 Replies View RelatedI need help creating a script that makes a log file in wich to save information about every user that uses the ftp command (information like username and date) and the server to wich he is trying to connect.
View 2 Replies View RelatedI am trying to read a file character wise and trying to write the same character to another file. In this process, I unable to read and write white spaces successfully to the new file. The script reads the white spaces but while writing the white space is lost. The section of the code, is given below. Please advice how can i read and retain the white space while writing to a new file.
Code:
if [ -s f_test.txt ] && [ -f f_test.txt ]; then
echo "File Exists !!"
while read -n1 char; do
[code]....
My C foo is terrible! I am working with some code which reads lines from a file and then reformats the lines and writes them to a new file.The input lines look like this:
Code:
+[NEOTEST?]
+[NEOTEST]
[code]...
My program need to monitor the foler to know which file under the folder is being opened/created for writing. I add the folder into watch list using inotify_add_watch, when a file -- say 'AA' -- is created, I'll get the event through read api call. But the inotify_event only have file name 'AA' and a event mask. these parameters can't help me to know how the 'AA' is created/openned. So I have to scan the /proc folder to get to know how is 'AA' created/openned. I don't think this is a efficient way, especially if there are lots of files are openned/created in a short time span.
View 3 Replies View RelatedThere is the Archive::Zip I think I can use with Perl 5.10 but I don't know how. I don't want to read or write any files, just zip something in memory, with best compression, like
$text = "this is a test";
$zippedtext = &Zip($text);
sub Zip {
[code]...
I guess it's only a few lines.
I have written interrupt handlers for a keyboard as well as the serial port RS232.
I have seen the book written by O'Reilly w.r.t the device drivers.
I wanted to know *exactly* what parts of Linux kernel should i understand well for having a crystal clear view of writing any kind of device driver ?
It it safe to read a shared integer while another thread is writing to it on a multicore system?
View 3 Replies View Relatedi am working on this thread: [URL] if it is better to open a file every time i need to write to it or should i keep a file open the whole time and when i am done with the script, close it and sendmail it out?
Or i just thought of this: i could keep concatenating to a string and just sendmail when done.
What do I need to start writing some php code? I've seen some tutorials where they install xampp, but I see it installs php, mysql and other stuff, my slackware already has mysql, so I don't know if installing xampp would cause some conflicts. What do I need to install considering that I already have mysql?
View 2 Replies View Related