Undocumented local scope for variable (even exported!)

[Pavel Tolkachev]

Configuration Information [Automatically generated, do not change]:
Machine: i386
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='i386' 
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='i386-redhat-linux-gnu' 
-DCONF_VENDOR='redhat' -DSHELL -DHAVE_CONFIG_H  -D_GNU_SOURCE 
-D_FILE_OFFSET_BITS=64  -I.  -I. -I./include -I./lib -I/usr/include -O2 
-march=i386 -mcpu=i686
uname output: Linux dwebr1 2.4.7-10 #1 Thu Sep 6 17:27:27 EDT 2001 i686 unknown
Machine Type: i386-redhat-linux-gnu

Bash Version: 2.05
Patch Level: 8
Release Status: release

Description:
      In some reasonably common code, bash seems to put the variables in 
undocumented local scope. Here is the code:
-----cut here-(script 2)---
a=1
export a
echo "a=$a"
echo "bc" | while read b; do
        a=2
        export a
        echo "a=$a"
done
echo "a=$a"
-----cut here--(script 2)--
and here is the output
-----cut here-(result 1)---
a=1
a=2
a=1
-----cut here-(result 1)---

At the same time, if we do not use a pipe to the while, for example:
-----cut here--(script 2)--
a=1
export a
echo "a=$a"
while true; do
        a=2
        export a
        echo "a=$a"
        break
done
echo "a=$a"
-----cut here--(script 2)--
The output is as expected:
-----cut here--(result 2)--
a=1
a=2
a=2
-----cut here--(result 2)--

In fact, it seems to me that the Korn-shell on my Linux box is actually 
implemented somehow using bash code because it gives the same result. There is 
no link, and the file size is different but it gives the same result for the 
script 1. The same script 1 run by the Korn-shell on Solaris or AIX gives the 
expected result (result 2). But bash gives the result 1 consistently on all 
those platforms (Linux AIX and Solaris) for script 1 (and result 2 for script 
2).

Repeat-By:
      See the code above -- no special circumstances are required

Have a nice day,
Pavel


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