problem in embeded command substitution

wrl · #1 (**permalink**) 08-07-2008

$ 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!

era · #2 (**permalink**) 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"

wrl · #3 (**permalink**) 08-07-2008

got it, thanks!

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