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problem in embeded command substitution

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# 1  
Old 08-07-2008
problem in embeded command substitution
$ echo $(tty|sed 's#/[a-z]*/##')
pts/0
$ who | grep $(tty|sed 's#/[a-z]*/##')
grep: 0652-033 Cannot open 0551-011.
grep: 0652-033 Cannot open Standard.
grep: 0652-033 Cannot open input.
grep: 0652-033 Cannot open is.
grep: 0652-033 Cannot open not.
grep: 0652-033 Cannot open a.
grep: 0652-033 Cannot open tty..
$


does anybody know why the command substitution gots error here?
does any rule forbid the command substitution in pipeline?
thanks in advance!
# 2  
Old 08-07-2008
Because it's in a pipeline, tty is not connected to your terminal.

You can work around it by running tty first, and then grepping.

Code:
tty=$(tty | sed 's#/[a-z]*/##')
who | grep "$tty"

# 3  
Old 08-07-2008
got it, thanks!
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