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Bash scripts may misbehave if SHELLOPTS is exported and 'monitor' is enabled
- From: "David Picton" <djpicton at gmail dot com>
- To: cygwin at cygwin dot com
- Date: Wed, 3 Jan 2007 13:44:36 +0000
- Subject: Bash scripts may misbehave if SHELLOPTS is exported and 'monitor' is enabled
I have noticed that a few scripts misbehave if SHELLOPTS is exported,
or defined in the environment before bash is first invoked. (I had
set SHELLOPTS=igncr in the system environment - but I've backed this
out to avoid the problems). The
problems seem to be caused by incorrect signal handling.
In particular, the current version of 'man' crashes with a strange message:
$ man bash
Bash is an sh-compatible command language interpreter that executes
commands read from the standard input or from a file. Bash also incor-
porates useful features from the Korn and C shells (ksh and csh).
Bash is intended to be a conformant implementation of the Shell and
Utilities portion of the IEEE POSIX specification (IEEE Standard
1003.1). Bash can be configured to be POSIX-conformant by default.
+ Stopped(SIGTTIN) ( cd "/usr/share/man" && ( echo ".pl 1100i"; /usr/
bin/cat '/usr/share/man/man1/bash.1'; echo ".\\\""; echo ".pl \n(nlu+10" ) | /us
r/bin/tbl | /usr/bin/nroff -Tlatin1 -mandoc | /usr/bin/less -isrR )
Error executing formatting or display command.
System command (cd "/usr/share/man" && (echo ".pl 1100i"; /usr/bin/cat '/usr/sha
re/man/man1/bash.1'; echo ".\\\""; echo ".pl \n(nlu+10") | /usr/bin/tbl | /usr/b
in/nroff -Tlatin1 -mandoc | /usr/bin/less -isrR) exited with status 38144.
No manual entry for bash
(I tested this on a fresh installation of the Cygwin base packages, so
sure that other people will be able to reproduce it! I've reproduced
it on two machines, both running Windows XP Professional. Note that I
have to type 'stty sane' to restore normal terminal operation after
the bug has occurred.)
It turned out that the problem has something to do with the 'monitor'
option being enabled. Normally it would be turned off in
noninteractive scripts, but if SHELLOPTS is in the environment the
setting (turned on by interactive shells) gets propagated to all
The bug disappears if:
1. I keep SHELLOPTS out of the environment, or
2. I change /bin/nroff to use /bin/ash instead of /bin/bash, or
3. I disable the monitor option (set +o monitor) before invoking man
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