Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!ukc!edcastle!lfcs!kgg
From: kgg@lfcs.ed.ac.uk (Kees Goossens)
Newsgroups: comp.windows.x
Subject: Re: io redirect of xterm -e cmd
Message-ID: <3227@castle.ed.ac.uk>
Date: 10 Apr 90 09:50:05 GMT
References: <3222@castle.ed.ac.uk> <9005@chaph.usc.edu>
Reply-To: kgg@lfcs.ed.ac.uk (Kees Goossens)
Organization: Laboratory for the Foundations of Computer Science, Edinburgh U
Lines: 59

In article <9005@chaph.usc.edu> jeenglis@alcor.usc.edu (Joe English) writes:
>kgg@lfcs.ed.ac.uk (Kees Goossens) writes:
>>I would like to redirect some of the output of a program I usually run as
>>xterm -e program into a separate X window.
>>Why doesn't the following work?
>>
>>{
>>	FILE *f;
>>	f = open ( "/tmp/zap", "w" );
>>	system "/usr/local/bin/X11R4/xterm -e cat /tmp/zap";
>>
>>	... here I use fprintf(f,...); for writing to that X window
>>	    and fprintf(stdout,...); for writing to the X window in
>>	    which the program was started ...
>>
>>	fclose(f);
>>}
>
>The problem is, cat only reads to the end of the file
>and then exits.  
>
>If you use 'tail -f' instead of 'cat' in the call to
>system() it will work, but you have to get the pid
>of the tail or xterm process and kill it or else it
>will never exit.

The following works:
{
FILE *file = NULL;
int  i = 0;

	if ( ( file = fopen ( "tmp", "w" ) ) == NULL ) {
		printf("Could not open file\n");
		exit(-1);
	}
	system ("xterm -geometry 80x24+0+0 -e tail -24lf tmp &");
	for (i=0; i<100; i++)
		fprintf ( file, "Hello there %d\n", i );
	fclose(file);

	... and need to kill xterm here ...
}

>
>A better solution would be to use 'f=popen("xterm -e cat")' 
>instead of a temporary file.
>
This does not work, as the stdin is inside the window, rather than f,
so it'll just sit there until you type ^D inside the window.
Is there a way of curing this? (It'd be nicer than the solution above.)

>--Joe English

	Kees
----
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