Two more critters for your menagerie
Code:
% uname -a
NetBSD hp.lan 7.99.25 NetBSD 7.99.25 (GENERIC.201601041220Z) #0: Mon Jan 4 14:54:30 UTC 2016 builds@b41.netbs\
d.org:/home/builds/ab/HEAD/i386/201601041220Z-obj/home/source/ab/HEAD/src/sys/arch/i386/compile/GENERIC i386
% . subshell.sh
setting a=1 ...
About to enter subshell ...
From within subshell the value of a : 1
Assigning 2 to a ...
From within subshell the value of a : 2
Working directory changed to /etc
Leaving subshell
Back home from trip to subshell ...
Value of a : 1
Working directory: /not/etc
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% uname -a
SunOS redacted 5.10 Generic_150400-28 sun4v sparc sun4v
% . subshell.sh
setting a=1 ...
About to enter subshell ...
From within subshell the value of a : 1
Assigning 2 to a ...
From within subshell the value of a : 2
Working directory changed to /etc
Leaving subshell
Back home from trip to subshell ...
Value of a : 1
Working directory: /not/etc