David Korn writes:
> cc: [EMAIL PROTECTED]
> Subject: Re: [ast-users] How to redirect terminal stdin/stout to implement a
> gdb-like "set inferior tty" in kshdb?
> --------
>
> > Recently I needed to debug a GNU autoconf configure script which seems
> > to do funky things with stdin and stdout. I realized that the shell
> > debuggers really should have the equivalent of gdb's "set inferior
> > tty" (
> > http://www.mcs.vuw.ac.nz/cgi-bin/info2www?(gdb)Input/Output)
> I tried this url and I got the message
> Sorry! - Couldn't find target: "Input/Output)" in file "gdb".
Sorry, the outside parentheses were not indented to be part of the URL. So
remove that final ")". Or to a google search for:
gdb 'set inferior-tty'
> >
> > The below is a little test that I came up with.
> >
> >
> > #!/usr/local/bin/ksh
> >
> > exec 7<&0 </dev/null 6>&1 # Line taken from an autoconf "configure"
> > script.
> > #...
> > typeset -i _Dbg_fdi
> > exec {_Dbg_fdi} <>/dev/pts/1
> > while read "foo >" args <&${_Dbg_fdi}
> > print -- "$line" >&${_Dbg_fdi}
> > done
> >
> > Unfortunately this doesn't work. I get the message:
> >
> > exec: {_Dbg_fdi}: not found
> That is because you put a space between {_Dbg_fdi} and <>. Just as a digit
> must preceded the redirection operator without a space, the same is true
> for {...}.
Ah, foiled again whether spaces must be/cannot be inserted. Thanks.
> >
> > Also, I'd like to test to see if a string name of a device is a valid
> > terminal. Here's what I'm currently using:
> >
> >
> > function _Dbg_is_tty {
> > (( $# != 1 )) && return 1
> > [[ -r "$1" && -w "$1" ]] && return 0
> > return 1
> > }
> Shouldn't [[ -t 1 ]] work?
If you mean -t $1 then, then my understanding is that -t uses file
descriptors; parameter $1 is the name of the device you want to
consider using as a tty.
If you mean -t 1 as in file descriptor 1, that works, but the name of
the device comes from the user. At this point I haven't tried issued a
redirect to open the name to get a descriptor yet. I could do that and
then make the test test, but then I have to make sure that file
descriptor (which might not be 1 because we're debugging a program and
the program might be using 1 itself) is moved around and that on error
when I don't have a valid tty recovery keeps the old file descriptor.
> >
> > One could also throw in a test for character devices. But is there
> > something better?
> >
> > Thanks.
>
> David Korn
> [EMAIL PROTECTED]
>
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