Using a Variable in a sed command called in Tcl Sc

2019-09-01 06:23发布

问题:

I want to use the following command in a tcl script :

sed -n '452,$ { /wire/ {p;q} }' /tmp/foo

For that I have changed this command as follow :

set MIDLINE2 [ exec sed -n {1134,$ {/wire/{=;q}}} foo.txt ] 

It gives me correct answer but in place 1134 I want to use variable $MIDLINE that has value 1134. How can I do that ? Please suggest some way.

回答1:

This is a simple problem of quoting. You're using curly braces which inhibits variable substitution. Since you want variable substitution you need to use something else.

set MIDLINE2 [ exec sed -n "$MIDLINE,\$ {/wire/{=;q}}" foo.txt ]

Notice that you have to put a backslash in front of the literal $, otherwise Tcl will try to substitute that, too.



标签: tcl