how to use exceptfds argument in select system call Post: 302213912

Sponsored Content

Top Forums UNIX for Advanced & Expert Users how to use exceptfds argument in select system call Post 302213912 by jim mcnamara on Friday 11th of July 2008 10:17:22 AM

07-11-2008

Registered User

Code:

 #define MASK(f)     (1 << (f))
           #define NTTYS 4

                int tty[NTTYS];
                int ttymask[NTTYS];
                int readmask = 0;
                int readfds;
                int nfound, i;
                struct timeval timeout;

                   /* First open each terminal for reading and put the
                    * file descriptors into array tty[NTTYS].  The code
                    * for opening the terminals is not shown here.
                    */

                for (i=0; i < NTTYS; i++) {
                   ttymask[i] = MASK(tty[i]);
                   readmask |= ttymask[i];
                }

                timeout.tv_sec  = 5;
                timeout.tv_usec = 0;
                readfds = readmask;

                /* select on NTTYS+3 file descriptors if stdin, stdout
                 * and stderr are also open
                 */
                if ((nfound = select (NTTYS+3, &readfds, 0, 0, &timeout)) == -1)
                   perror ("select failed");
                else if (nfound == 0)
                   printf ("select timed out \n");
                else for (i=0; i < NTTYS; i++)
                   if (ttymask[i] & readfds)
                      /* Read from tty[i].  The code for reading
                       * is not shown here.
                       */
                else printf ("tty[%d] is not ready for reading \n",i);

jim mcnamara

View Public Profile for jim mcnamara

Find all posts by jim mcnamara

10 More Discussions You Might Find Interesting

1. UNIX for Advanced & Expert Users

how to differentiate system call from library call

Hi, Ho do I differentiate system call from library call? for example if I am using chmod , how do I find out if it is a system call or library call? Thanks Muru

2. Programming

error "Invalid argument" returned after call sched_setscheduler

the code is below and the was run on Solaris 9. ----------------------------- struct sched_param param; param.sched_priority = 99; if(sched_setscheduler(0, SCHED_RR, &param) == -1) { perror("setting priority"); exit(1); } ------------------------------- after the...

3. Shell Programming and Scripting

Function call with argument doubt

Hi all, I am having a problem with user defined function call. I am new into the concept of shell script UDFs. My function is: iterate_directory() { cd $1 k=0 for i in * do if then ARR=${i} fi done echo ${ARR } }

4. Programming

Having some trouble with select() call in C

I have this while loop: while (notdone) { //Set the timers waitd.tv_sec = 5; waitd.tv_usec = 0; FD_ZERO(&tempreadfds); FD_ZERO(&tempwritefds); FD_ZERO(&readfds); /* initialize the read fd set */ FD_ZERO(&writefds); /* initialize the write fd set */ ...

5. Shell Programming and Scripting

Passing argument to system call in awk script

So, I have this script. It reads a CSV file that has a mixture of object names with IP addresses (parsing out that part I have working), and object names which have a DNS name. I want to be able to run a "dig +short" based off of the name given to me in the line of the awk script, and then deal...

6. Programming

select() system call takes longer than the timeout specified

Below is my code. Every once in a while the select call takes as long as 150 seconds (discovered by printing time before and after this statement) while the timeout specified into it is only 1 second. Any clue why? I can't believe that select call which has been around for centuries can have a bug,...

7. UNIX for Dummies Questions & Answers

How to select correct partition and kernel argument for grub?

I use command-line mode of GRUB to load kernel, but I can not know how to chose the partition and kernel argument, as followed : please tell me how to do deal with , thanks!

8. Homework & Coursework Questions

program to send messages to parent using pipes and select system call

Write a program using select, which will create some number of child processes that continuously send text messages to the parent process using pipes. Each child has its own pipe that it uses to communicate with the parent. The parent uses select () to decide what pipes should be processed to...

9. UNIX for Advanced & Expert Users

Issues with select system call

1. We are using client-server model communication using TCP/IP protocol 2. The TCP socket created with O_NON_BLOCK flag 3. When we make attempt to send large data to other process, the send is partially successful. It means we attempt to send 90K data, OS sent only 40K data successfully. ...

10. Shell Programming and Scripting

Conditionally replace nth argument of every function call

I have very large perl source code file and I want to replace every occurrence function say foo,The function foo has some arguments and I want to replace 2nd argument,the current argument is hex integer and i want to replace it to equivalent string.Also I want to replace function name foo with...

LEARN ABOUT OPENSOLARIS

tc-tcindex

Traffic control index filter(8)                                        Linux                                       Traffic control index filter(8)

NAME

       tcindex - traffic control index filter

SYNOPSIS

       tc filter ... tcindex [ hash SIZE ] [ mask MASK ] [ shift SHIFT ] [ pass_on | fall_through ] [ classid CLASSID ] [ action ACTION_SPEC ]

DESCRIPTION

       This  filter allows to match packets based on their tcindex field value, i.e. the combination of the DSCP and ECN fields as present in IPv4
       and IPv6 headers.

OPTIONS

       action ACTION_SPEC
              Apply an action from the generic actions framework on matching packets.

       classid CLASSID
              Push matching packets into the class identified by CLASSID.

       hash SIZE
              Hash table size in entries to use. Defaults to 64.

       mask MASK
              An optional bitmask to binary AND to the packet's tcindex field before use.

       shift SHIFT
              The number of bits to right-shift a packet's tcindex value before use. If a mask has been set, masking is done before shifting.

       pass_on
              If this flag is set, failure to find a class for the resulting ID will make the filter fail and lead to the next filter  being  con-
              sulted.

       fall_through
              This  is  the  opposite  of  pass_on  and the default. The filter will classify the packet even if there is no class present for the
              resulting class ID.

SEE ALSO

       tc(8)

iproute2                                                            21 Oct 2015                                    Traffic control index filter(8)

10 More Discussions You Might Find Interesting

1. UNIX for Advanced & Expert Users

how to differentiate system call from library call

Discussion started by: muru

2. Programming

error "Invalid argument" returned after call sched_setscheduler

Discussion started by: robin.zhu

3. Shell Programming and Scripting

Function call with argument doubt

Discussion started by: canishk

4. Programming

Having some trouble with select() call in C

Discussion started by: Legend986