[tlug] Sticky problem with pipes, head and tails

[Stuart Luppescu <slu@example.com>]

Hello, As you can see from my signature in this message (yes, I know
it's longer than 4 lines), I use the R fortune function to generate a
fortune, which is then fed to the signature program, which constructs a
named pipe containing the fortune-bearing sig, which is then included in
mail messages. The problem is that it's got extraneous junk in it and I
can't figure out how to get rid of it. This is the command that
generates the fortune:

/usr/bin/R --no-save --no-restore -q < /home/sl70/print-fortune.R

This produces this:
> library(fortunes)                                                             
> fortune()

Michael Watson: Hopefully this one isn't in the manual or I am about to get shot :-S
Peter Dalgaard: *Kapow*...
   -- Michael Watson and Peter Dalgaard (question on axis())
      R-help (February 2006)

> 

I would like to remove the first two lines and the last line, so I
changed the command to this:
/usr/bin/R --no-save --no-restore < /home/sl70/print-fortune.R  |tail \
-n  +23  | head -n -2 2> /dev/null

That give the desired result when I run it at the command line, but when
I feed it to the signature program, I get this message:

Program /usr/local/bin/r-fortune doesn't seem to exist

This is the program code that produces this error:

         /* check for existence of program by forking and then trying to
               exec() it in the child */
            pid = fork();
            switch (pid) {
            case -1:            /* oh well */
                perror("Couldn't fork() a child process");
                exit(EXIT_FAILURE);
            case 0:             /* in child */
                /* close stdout */
                close(1);
                execlp(producer, producer, (char *) 0);
                exit(EXIT_FAILURE);
            default:
                waitpid(pid, &exit_status, 0);
                if (exit_status != EXIT_SUCCESS) {
                    fprintf(stderr, "Program %s doesn't seem to exist\n",
                            producer);
                    exit(EXIT_FAILURE);
                }

Unfortunately, I don't understand this at all. Can anyone give me a clue
as to what's happening?

Thanks.
-- 
Stuart Luppescu -=- slu .at. ccsr.uchicago.edu        
University of Chicago -=- CCSR 
才文と智奈美の父 -=-    Kernel 2.6.34-gentoo-r1                
> library(fortunes) > fortune()  Maybe you should
 contact Microsoft, and get them to modify their
 tools so they work on the R sources?    -- Duncan 
 Murdoch (answering the question if there is a way 
 compiling the R       sources using VisualC++)    
 R-help (April 2004)  >

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