Woops.
"file descriptor" 0 is the standard input.
file descriptor 1 is the standard output
file descriptor 2 is the standard error output
On Wed, Apr 29, 2009 at 09:15:06AM +0100, Ralph Corderoy wrote:
>
> Hi Michail,
>
> > may be I am missing something trivial, but I can not find a
> > command-line switch in groff to direct output to file.
>
> No, I'm pretty certain there isn't one.
>
> > Output redirection is no problem in shell scripts, but if groff is to
> > be spawned from another program it becomes a problem, either you spawn
> > a shell runing a script or spawn groff and have to bother with piping
> > output. You can not just fire off groff and forget about it. What a
> > miss :(
>
> When you say "spawn a shell runing a script" I assume you know you can
> give the shell a command to execute with the -c option without a script
> file needing to exist on disc? For example, in C,
>
> ret = system("groff foo.tr >foo.ps");
>
> will cause sh(1) to be execve(2)'d with
>
> execve("/bin/sh", ["sh", "-c", "groff foo.tr >foo.ps"], [/* 55 vars */])
>
> So yes, that does involve a shell being started just to run groff, but
> then you're wanting the shell's I/O redirection syntax to be
> interpreted. As I think you're saying, you could avoid this by manually
> forking and setting up file descriptor 0 to be writing to foo.ps before
> execing groff but it's hassle and system() is just easier.
>
> An option shouldn't be added to groff to do this. By that logic, awk,
> sed, make, date, and wc should all grow an --output option too.
>
> Cheers,
>
> Ralph.
--
Mike Bianchi
