$() fails if stdin and stdout are not open

Article View: gnu.bash.bug

Article #880

#880

From: Michael Cook
Date: Wed, 12 Aug 1992 17:28

33 lines
1462 bytes

If bash is run with stdin and stdout closed, the backquoting mechanism fails.
Look:

bash$ bash -c 'echo foo$(echo bar)baz >/dev/tty' >&- <&-
foobaz

If either stdin or stdout is open, it works okay:

bash$ bash -c 'echo foo$(echo bar)baz >/dev/tty'
foobarbaz
bash$ bash -c 'echo foo$(echo bar)baz >/dev/tty'          <&-
foobarbaz
bash$ bash -c 'echo foo$(echo bar)baz >/dev/tty'      >&-
foobarbaz
bash$ bash -c 'echo foo$(echo bar)baz >/dev/tty'      >&- <&-
foobaz
bash$ bash -c 'echo foo$(echo bar)baz >/dev/tty' 2>&-
foobarbaz
bash$ bash -c 'echo foo$(echo bar)baz >/dev/tty' 2>&-     <&-
foobarbaz
bash$ bash -c 'echo foo$(echo bar)baz >/dev/tty' 2>&- >&-
foobarbaz
bash$ bash -c 'echo foo$(echo bar)baz >/dev/tty' 2>&- >&- <&-
foobaz
bash$

(On our system (ULTRIX 4.2), when an X session is started, the $SHELL that is
run to startup the window manager has stdin and stdout closed.  Lord only
knows why...)

Bash should be made smart enough to handle this, shouldn't it?

Michael.

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Message-ID: <mcook.713640511@fendahl.dev.cdx.mot.com>

Path: arc1-ca.pugleaf.net!sparky!uunet!cis.ohio-state.edu!merlin.DEv.cdx.mot.COM!mcook

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Newsgroups: gnu.bash.bug
Path: arc1-ca.pugleaf.net!sparky!uunet!cis.ohio-state.edu!merlin.DEv.cdx.mot.COM!mcook
From: mcook@merlin.DEv.cdx.mot.COM (Michael Cook)
Subject: $() fails if stdin and stdout are not open
Message-ID: <mcook.713640511@fendahl.dev.cdx.mot.com>
Sender: gnulists@ai.mit.edu
Organization: Motorola Codex, Canton, Massachusetts
Distribution: gnu
Date: Wed, 12 Aug 1992 17:28:31 GMT
Approved: bug-bash@prep.ai.mit.edu
Lines: 34