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From: arisawa@ar.aichi-u.ac.jp
Date: Wed,  9 Aug 2006 19:00:34 +0900
To: Fans of the OS Plan 9 from Bell Labs <9fans@cse.psu.edu>
Subject: [9fans] Environment variable
Topicbox-Message-UUID: 9ad2d132-ead1-11e9-9d60-3106f5b1d025

Hello 9fans,

I found something weird about environment variable.

term% a=alice
term% b=$a
term% xd -c /env/a
0000000   a  l  i  c  e 00
0000006
term% xd -c /env/b
0000000   a  l  i  c  e 00
0000006
term%

OK. /env/a is same as /env/b as it should be.

term% a=''		# null string is assigned to a
term% b=$a
term% xd -c /env/a
0000000  00
0000001
term% xd -c /env/b
0000000  00
0000001
term%

This is also OK.


term% b=`{cat /env/a}
term% xd -c /env/b
0000000
0000000
term% b=`{echo $a}
term% xd -c /env/b
0000000
0000000
term% b=`{echo ''}	# echo null string
term% xd -c /env/b
0000000
0000000
term%

??? /env/b is empty ! not same as /env/a

term% xd -c $a
xd: can't open
term%

OK I have not a file of $a

term% xd -c $b

xd is waiting a data from stdin!

Bug or specification?

Kenji Arisawa