$() fails if stdin and stdout are not open

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1 total messages Started by Michael Cook Wed, 12 Aug 1992 17:28

#880

Author: 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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