using sed in a tcl file

Question

Hi I am new tcl and have faced the issue like below.

In this code, I was trying to get only line 1 and 2 from a file and want to put them into another variable. But this code didn't work for me.

set sed_com "${line1},${line2}p";               # the value of this sed command is 1,2p
set tmp  [exec sh -c {sed -n "${sed_com}" file.tmp | tail -n 1}]; # this one won't work 
set tmp  [exec sh -c {sed -n "1,2p" file.tmp | tail -n 1}];       # this one will work

I was wondering if there is a way that we could make the tcl file interpret it like the line 3?

Answer 1

Why are you complicating things by throwing in the sh -c ? You can just do:

set tmp [exec sed -n $sed_com file.tmp | tail -n 1]