The UNIX and Linux Forums - High Level Programming

noob question about fork

edgarvm — Fri, 20 Nov 2009 00:50:21 GMT

Hi everyone:

I'm developing a dynamic library for notifications, this library is used for a daemon that i've programmed, when something goes wrong the library should send an email to an administrator, but since sending an email is a non-vital process then it can fail (it should work as an asynchronous process) so i'm considering to do that by using the fork function, however the entire process of daemon will be forked and i would be responsible for destroying the child process, so my question is, does exist any way more efficient to do this?

thanks in advance

stat64 support on 32bit platform

guru13 — Wed, 18 Nov 2009 16:18:21 GMT

I have to get the size and ownership of a file on a 32 bit solaris 10.stat function fails to provide the information as the file size is greater than 2GB(26GB).Is stat64 supported on 32 bit platforms.Can i use the function on all the platforms

Test Coverage - executing this code

Jakeman1086 — Tue, 17 Nov 2009 22:23:12 GMT

Hi,

I am trying to gain test coverage on the 'fold' program in unix and am having difficulty executing the following code:

Code:

if(ferror (istream))

{

        error (0, errno, "%s", filename);

        if(!STREQ (filename, "-"))

                fclose (istream);

        return 1;

}

if (!STREQ (filename, "-") && fclose (istream) == EOF)

{

        error (0, errno, "%s", filename);

        return 1;

}

How could I cause an error to occur in the input stream using the fold command in the command prompt (i.e. fold < input).

Thank you!

Unicode programing in C

broli — Tue, 17 Nov 2009 20:25:14 GMT

im starting to go a little serious with c, woking in a personal project that will read a xml, which might contain Unicode characters (i know it will on my system, which is set to es_AR.UTF-8)

im using mxml, and the documentation says it uses utf8 internally (no worries here).
so i need to be sure im using utf8 in my program. to be sure that i can safely interact with mxml and to be sure my program will work in all languages.

i have been reading alot, but i dont quite fully get how i can accomplish this.

im going for something simple, something easy that wont demand much of me.

my program will read user input (from cli for now, gtk later), and will save it in xml (is a config file for other app). it will also have the option to read a xml, and use it as a base for a new one

now, i have a few concrete questions.
a) do i have to use a special type of variable?
if a) is true, then i need a hole new set of functions? (for strcmp, or strstr)
b) can i work with unicode characters using char *?
if b) is true, how do i "make" them utf8?
c) is a mix of the above? then how to choose the mix ratio?

i appreciate any help, manual, link, ect that can help me understand how this works. (that includes source code)

thanks

cc -- Unsatisfied symbols -- on HP-UX 10.2

Dirk_ — Tue, 17 Nov 2009 16:25:50 GMT

Greetings,
I am slowly learning a few things but am far from being an expert. I am at the point now that I
would like to be able write some ANSI C code on HP-UX 10.2. Just a hobbie... I am just using cc,
which came with the HP-UX 10.2 ...
I don't have the manuals for the development environment...
Anyway, I have the following sample code that illustrates that I am missing a library file
when cc attempts to link??? That is the conclusion I have come to.
I have looked through man pow, and man math and have not found the information I am looking for.

I am not sure 1) which library file is missing and 2) the syntax I need to use to poperly compile
and link in the object files.
Following is sample code that illustrates the issue I am having with cc
Thanks in advance,
Dirk

Code:

$ uname -a

HP-UX green B.10.20 A 9000/782 2015827886 two-user license

=========

cat ex4_6.c

#include 

#include 

 

 

main ()

{

float polyresult;

polyresult = 3 * powf(2.55, 3) + 2 * powf(2.55, 2) + 6;

printf("the result is %f\n", polyresult );

 

}

 

 

$ cc ex4_6.c

/usr/ccs/bin/ld: Unsatisfied symbols:

powf (code)

DOM query selected path and show as xml

penyu — Tue, 17 Nov 2009 11:35:11 GMT

First, I am sorry if this question not this room scope,

I have a XML file :

file: book.xml

Code:











  Everyday Italian

  Giada De Laurentiis

  2005

  30.00







  Harry Potter

  J K. Rowling

  2005

  29.99

I using this script If I want to show output of my script as xml file:

Code:

Now, I want to select specific path of XML node. The output that I want is like:

Code:







  Everyday Italian

  Giada De Laurentiis

  2005

  30.00

and this is my script:

Code:

Unfortunatelly, the script totally error. I dont know how to fix this. :(

Could you somebody please tell me how to print output only selected path criteria as xml?

Your answer really appreciated,

Thanks,
Denny

String copy in C language

tqlam — Mon, 16 Nov 2009 17:18:46 GMT

Hello,

I have a text file (FILE.txt) that contains the following information:

userAxxx.name@email.com userA
userBxxx.name@email.com userB
userxxCx.name@email.com userC
and more....

in scripting, I can easily do a grep and awk to store an email info into a string variable as following:

EMAL=`grep userA | awk '{print $1}' FILE.txt`
or
EMAIL=`nawk '$2 == "userB" {print $1}' FILE.txt

BUT, how do I translate above into C language?

I'm new in c programming and very appreciate for your help.

Thanks so much,
tqlam

how to execute the sql quires from shell script?

vij_krr — Mon, 16 Nov 2009 05:56:11 GMT

hi all,

I'm new to shell scripting, i want to know how to use the sql statements from the shell script? is there any documents or pdf to learn from the begining? plese provide me some useful links on the same.

Thanks all in advance..,:b:

pthread and mutex question

michael23 — Sun, 15 Nov 2009 18:28:28 GMT

Hello,
I have got some issue with the struct variable with passed arguments
the variable in the sturct is only recognize the last value their assigned to
I'm pretty confused why the mutex didn't work out

here is my program:

Code:

#include

#include

 

pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;

struct arg_struct {

  int arg1;

  int deposit;

};

 

void *print_the_arguments(void *arguments)

{

  pthread_mutex_unlock(&lock);

  struct arg_struct *args = arguments;

  int j;

  j = args -> deposit;

  printf("%d\n", args -> arg1 + j);

  pthread_exit(NULL);

  return NULL;

  pthread_mutex_lock(&lock);

}

 

int main()

{

  pthread_t some_thread;

  struct arg_struct args;

  args.arg1 = 5;



  args.deposit = 3;



  //pthread_mutex_unlock(&lock);

  pthread_create(&some_thread, NULL, &print_the_arguments, (void *)&args)   != 0;

  //pthread_mutex_lock(&lock);



  args.deposit=10;

  pthread_create(&some_thread, NULL, &print_the_arguments, (void *)&args)   != 0; 



  return pthread_join(some_thread, NULL);

}

I'm expect the result would like this
8
18

instead I've got this
15
15

any idead to solve this problem?
thanks in advance :)

Connecting child processes to the server

xyzt — Sat, 14 Nov 2009 20:47:48 GMT

I try to fork child processes and they connect to a server.
At the beginning, I create a socket(1 socket for all child processes), after that at each child process I connect to the server using connect function but I get this error msg:"Transport endpoint is already connected"

but if I create a socket for every child processes and connect the child processes to the server, I get no error.

if the memory space of the parent is copied, why this problem occurs?what is the difference between the two methods?

Need a flight program

linux2flight — Sat, 14 Nov 2009 00:05:01 GMT

I am building a UAV and building a computer control system. I am wanting to use a small linux disro (puppy, damn small) so that i need no drives except sd card reader. I am wondering if anyone knew of a flight control program or something that can be motified to work. The basics are that i am gonna use a 3g cell to communicate and for gps, a small decent mother board an amd phenom II processor, 2X 4g ddr2, and a sdcard reader. NO DRIVES- too much weight. I have tested the prototype and it flies. I know a phone isnt instant but thats ok. it will used to give cooridants and to give commands. I plan to have the computer to control, by usb, a control board but want some input before i start building it. Any ideas or suggestions or help would be appreciated.

Shell SQLPlus

nmahendran — Fri, 13 Nov 2009 12:57:59 GMT

Hi,

I am trying to execute the update statment in shell sqlplus.But nothing prompts.if i do ctrl+c i got the below error.

SQL> update table set enabled='N' where type_code='xx';
^C update table set enabled='N' where type_code='xx'
*
ERROR at line 1:
ORA-01013: user requested cancel of current operation.

if i use select statement records are retrived,
is it i need any access permissions...if so how to give that
can anyone advice this.

Hairy Problem! lseek over 4G

macroideal — Fri, 13 Nov 2009 08:57:12 GMT

recently my project needs me to lseek a position over 4G size....
i found in linux or unix the parameters are all ulong 32 bits...the limit dooms the movement of a position over 4G
I was told that i should lseek64 to meet my need... but i have no idea where i can get the function neither by "man lseek64"....
do you how to use the function "lseek64" or similiar functions by which i can jump over 4G, thanx .:(:(:(:(:(:(:(:(:(

Compile a proc/c++ file in debug mode.

ehari — Thu, 12 Nov 2009 10:56:54 GMT

Hi,

I'm using the following commands to execute a proc file, but I'm unable to debug the program. What modifications do I need to make in the command options to debug the program created.

I have a proc1.pc file, using the following three steps to generate the proc1 exe. After the proc1 exe is generated, I'm unable to debug that file. Please help.

Code:

1.       proc proc1.pc

2.       cc -I ${ORACLE_HOME}/precomp/public -c proc1.c

3.       cc -bloadmap:proc1.map -lm -lld -L $ORACLE_LIB $ORACLE_LIB/libcommon9.a $ORACLE_LIB/libgeneric9.a -lclntsh -o proc1 proc1.o

makefile help

vij_krr — Thu, 12 Nov 2009 10:05:01 GMT

Hi all,

I'm new to make files . I'm writing a make file to compile and create .so files. i've 20 .cpp files. I want to compile one file at a time and then i've to create 1 .so for each file that i compiled.

for eg:

list.mk is having all the 20 .spp files.

name = a.cpp
name =+ b.cpp
....

if i give CC -o $(name) it is taking all the 20 at the same time. but i want to take one file at a time and compile it.

simply if i give
display:
@echo " Name = $(name) "

then it has to display
Name = a.cpp
Name = b.cpp etc..
not like Name = a.cpp b.cpp c.cpp n all..

Thanks in advance