rwl@franklin.ee.umr.edu (Wayne Little) (05/08/91)
From: rwl@ee.umr.edu (Wayne Little) Newsgroups: comp.sys.unix.wizards Subject: How to redirect just stderr under the C Shell? References: Sender: Reply-To: rwl@ee.umr.edu (Wayne Little) Followup-To: Distribution: world Organization: University of Missouri - Rolla Keywords: "C shell",csh, stderr, redirect Under the C shell, I know I can redirect both stdout & stderr with the ">&" combination; e.g. make >& make.log will put both the stdout and stderr ouputs in make.log. *BUT* after all these years I still can't figure out how to redirect *just* stderr independently of stdout under the C Shell. Under the Bourne shell, one can just do "N>" where N is the number of the file descriptor you want to redirect, so "2>" will redirect stderr. e.g. make > make.stdout 2> make.stderr would separate the stdout from the stderr in 2 different files as indicated. I'm at a loss under the C Shell. Can some wizard please come to my rescue and solve this 10-year mystery for me??? Thanks in advance, -- Wayne Little rwl@ee.umr.edu; Univ. of Missouri-Rolla EE Dept.; (314) 341-4546 "I have read in Plato and Cicero sayings that are very wise and very beautiful; but I never read in either of them: "Come unto me all ye that labour and are heavy laden." St. Augustine
tchrist@convex.COM (Tom Christiansen) (05/08/91)
From the keyboard of rwl@ee.umr.edu (Wayne Little):
:*BUT* after all these years I still can't figure out how to redirect
:*just* stderr independently of stdout under the C Shell.
:I'm at a loss under the C Shell.
In general, it can't be done.
Now, I'm sure someone will suggest
( foo > foo.stdout ) >& foo.stderr
but that's not right: stdout is mangled. Someone else
will suggest
( foo > /dev/tty ) >& foo.stderr
but that's not right, as stdout is no longer going where it
had been going.
If your system should support /dev/fd pseudo-devices, this
ought to work:
( foo > /dev/stdout ) >& foo.stderr
But few of us have that feature on our systems.
--tom
--
Tom Christiansen tchrist@convex.com convex!tchrist
"So much mail, so little time." willcr@bud.sos.ivy.isc.com (Will Crowder) (05/09/91)
In article <1991May08.154738.26889@convex.com>, tchrist@convex.COM (Tom Christiansen) writes: > From the keyboard of rwl@ee.umr.edu (Wayne Little): > > [How do I redirect stderr independent of stdout under C Shell?] > > In general, it can't be done. > > Now, I'm sure someone will suggest > > ( foo > foo.stdout ) >& foo.stderr > > but that's not right: stdout is mangled. How is stdout mangled? Is it because "isatty(fileno(stdout))" will no longer be true? > Someone else > will suggest > > ( foo > /dev/tty ) >& foo.stderr > > but that's not right, as stdout is no longer going where it > had been going. Now this, at least, I see. If the above were part of a pipeline in which stdout had already been redirected, things would go awry quite quickly, as well as in a number of other scenarios as well, I'm sure. Redirector emptor! :) :) :) |> If your system should support /dev/fd pseudo-devices, this |> ought to work: |> |> ( foo > /dev/stdout ) >& foo.stderr |> |> But few of us have that feature on our systems. I sure wish my system (Sun) did! That sounds like the right general solution to me. Actually, I suggested both of the above in e-mail, with the disclaimer "I'm no wizard." Glad I put that disclaimer on there...although I did get mail back from Wayne saying it worked fine for his particular case. |> -- |> Tom Christiansen tchrist@convex.com convex!tchrist |> "So much mail, so little time." ^^^^^^^^^^^ That's why I posted this... Will -------------------------------------------------------------------------------- Will Crowder, MTS | "I was gratified to be able to answer quickly, (willcr@ivy.isc.com) | and I did: I said I didn't know." INTERACTIVE Systems Corp. | -- Mark Twain
tchrist@convex.COM (Tom Christiansen) (05/09/91)
Quoting myself...
:If your system should support /dev/fd pseudo-devices, this
:ought to work:
:
: ( foo > /dev/stdout ) >& foo.stderr
:
:But few of us have that feature on our systems.
As has been pointed out to me in mail, no, that shouldn't work.
(All I can say is that I'm one who doesn't have such a feature.)
There is, however, one tried and true way to do this: :-)
sh -c "cmd 2>cmd.err"
--tom
--
Tom Christiansen tchrist@convex.com convex!tchrist
"So much mail, so little time." tchrist@convex.COM (Tom Christiansen) (05/09/91)
From the keyboard of willcr@ivy.isc.com:
:In article <1991May08.154738.26889@convex.com>, tchrist@convex.COM (Tom
:Christiansen) writes:
:>
:> Now, I'm sure someone will suggest
:>
:> ( foo > foo.stdout ) >& foo.stderr
:>
:> but that's not right: stdout is mangled.
:
:How is stdout mangled? Is it because "isatty(fileno(stdout))" will no
:longer be true?
Perhaps stolen would have been a better word choice than mangled.
Let's same it's in a script that's being run like this:
script > script.out
The foo output no longer goes to script.out, where I expect it.
--tom
--
Tom Christiansen tchrist@convex.com convex!tchrist
"So much mail, so little time."