How to execute AWK in TCL list with variables?

Question

I need to run a few commands from terminal via a TCL script. This TCL script works fine.

set cmd_list [list {mkdir testdir} {cd testdir} ]
set dataportInterface "eth0"
lappend cmd_list [list ifconfig -a | grep -m 1 $dataportInterface]

However, as soon as I add the awk command, it starts failing. Error is "Failed : extra characters after close-brace".

lappend cmd_list [list ifconfig -a | grep -m 1 $dataportInterface | awk 'BEGIN {FS="[:]"} { print $1 } END {}' | xargs -t ethtool -S]

I have tried several possibilities, but none of them work. For example, if I try

lappend cmd_list {  }

then, $dataportInterface's value eth0 is not taken.

I tried putting a \ in front of all special characters (: " ' [ { and that threw the error $1 not recognized. I put the awk command in {{ brackets and that didn't work either. (error: doesn't recognize {{awk)

What is the correct way to go about this, and why?

In that case, $dataportInterface is not changed to eth0. However, if I hardcode eth0, it works. (But that's not what I'm looking for) — sbhatla
– sbhatla, Commented Nov 9, 2015 at 21:49
Fair enough. You'll need to use something to format your string then. Also you appear to have a stray ] after $dataportInterface in that ifconfig command. — Etan Reisner
– Etan Reisner, Commented Nov 9, 2015 at 21:53

Colin Macleod · Accepted Answer · 2015-11-09 21:52:44Z

1

Single quotes have no significance to Tcl - try changing '...' to {...}

answered Nov 9, 2015 at 21:52

Colin Macleod

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2 Comments

Peter Lewerin Over a year ago

@EtanReisner: wrapping the argument to awk in braces will not interfere with variable expansion in the argument to grep.

Etan Reisner Over a year ago

I understand what this answer was intending to say now. It should, in light of my comment and the response, be written more clearly and explicitly. In that it should explain what the issue is more specifically. Why changing the single quotes to {} (in place) will help. etc.

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