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Full Discussion: C Program to search and read all named pipes in current directory
Homework and Emergencies Homework & Coursework Questions C Program to search and read all named pipes in current directory Post 302578508 by natwickley on Thursday 1st of December 2011 06:33:45 PM
Old 12-01-2011
C Program to search and read all named pipes in current directory
Use and complete the template provided. The entire template must be completed. If you don't, your post may be deleted!

1. The problem statement, all variables and given/known data:


Write a C program to search the current directory for all pipes.

1. It will print the pipe names, one per line.
2. Print the number of pipes found.
3. Search for all pipes whose contents contain your ID and print the entire contents of that/those pipe(s).

2. Relevant commands, code, scripts, algorithms:

Running inside a bash shell, compiling with g++, professor provides a directory of pre-existing pipes and pipe writers to prevent the block that you get from waiting for a pipe read or write to start

3. The attempts at a solution (include all code and scripts):

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

int main()
{
FILE *read_fp;
char buffer[BUFSIZ + 1];
int chars_read;
memset(buffer, '\0', sizeof(buffer));
read_fp = popen("uname -a", "r");
if (read_fp != NULL) {
chars_read = fread(buffer, sizeof(char), BUFSIZ, read_fp);
if (chars_read > 0) {
printf("Output was:-\n%s\n", buffer);
}
pclose(read_fp);
exit(EXIT_SUCCESS);
}
exit(EXIT_FAILURE);
}

4. Complete Name of School (University), City (State), Country, Name of Professor, and Course Number (Link to Course):
University of North Texas, Denton, Texas, USA
Course is 3600, "Systems" taught by Professor Goodman
www . cse . unt . edu /~goodman/CS3600/cs3600.html

Note: Without school/professor/course information, you will be banned if you post here! You must complete the entire template (not just parts of it).


I don't have a problem reading from the pipe. I can specify a named pipe with the popen command and read from a named pipe. The above code can do that. The problem I have is that I am given the task to read from all the named pipes in the directory using a C program. I can easily write a bash script like "for all files in *" do blah. I know that I can do a system call and I can make a system call for the pwd to figure some things out but I don't know how to isolate pipes from the general files inside the C program. In a bash script I can use "test" to do that but is there a way to suck a list of named pipes into a C program in Unix? Finding named pipe assistance seems to be quite difficult on google so I'm trying out here.

Any ideas how to pull in the list of pipes into the C program?
 

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LEARN ABOUT DEBIAN

togeomview

TOGEOMVIEW(1gv) 														   TOGEOMVIEW(1gv)

NAME

       togeomview - send commands or OOGL objects to geomview

SYNOPSIS

       togeomview [-c] [-g]  [pipename	[program args ...]]

DESCRIPTION

       togeomview  sends a stream of geomview commands, or OOGL-format geometric data, to a cooperating copy of geomview.  If geomview is not run-
       ning, it is automatically started.  ('geomview' must be on the $PATH of the user running 'togeomview' in order for this to work.)

       Typical usage is:
	    someprogram | togeomview	(to send commands) or
	    someprogram-generating-OOGL-data | togeomview -g  (to send geometry)
       i.e. a program pipes geometric data into ``togeomview''; the data is displayed by a copy of geomview run with the  -M  option  and  a  name
       matching the one given to togeomview.

       Togeomview  uses  a  named  pipe  in  the directory /tmp/geomview to communicate with geomview.	If unspecified, the pipe's default name is
       "OOGL".	When sending geometry (-g), a geomview object with the same name as the pipe appears in geomview's object browser.

       By default, when no suitable copy of geomview is running, togeomview invokes "geomview" with arguments  specifying  the	appropriate  named
       pipe.  A different command may be specified as in:

	    togeomview	OOGL  gv -wpos 300x300 -c my_startup_script

       which  communicates  through a pipe named OOGL, and (if necessary) invokes the given gv command.  The pipe name is required if a command is
       specified.

       After togeomview has created it, the named pipe may be written as an ordinary file.  For example, one could use

	    togeomview pipename < /dev/null

       to invoke a listening copy of geomview, and then run a program which simply wrote to /tmp/geomview/pipename.

FILES

       /tmp/geomview

BUGS

       The pipe-based communications scheme imposes several restrictions.

       If no copy of geomview is reading from the pipe, or if geomview gets far enough behind, a program writing data to  ``togeomview''  will	be
       forced to block after sending a few kilobytes.

       Because of the buffering in the pipe, the sender may be substantially ahead of the geomview display.

       If  geomview  exits,  the sending program receives a write-on-broken-pipe (SIGPIPE) signal, which will kill it unless measures are taken to
       catch or ignore that signal.

       Only one copy of geomview can read from a given pipe at a time.	If a second copy attempts to read from it, both will probably fail.   It's
       fine to have multiple copies of geomview reading from different pipes.

       Note  that  togeomview  will  invoke  geomview if no extant copy is listening to the relevant pipe; it can't connect to an existing copy of
       geomview started by other means.

SEE ALSO

       geomview(1), oogl(5)

Geometry Center 						    21 May 1993 						   TOGEOMVIEW(1gv)
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