tclexpect

read variable inside text file used as list in TCL

I've this part of TCL/expect code:

commands.txt sample content:
  configure terminal
    interface Vlan10
    ip address 192.168.1.1 255.255.255.0 

set commands "commands.txt"
#
set f [open "$commands"]
set commands [split [read $f] "\n"]
close $f
#
foreach cmd $commands {
    expect { 
    "*#" {
    send "$cmd\n" 
}

and it works as intended, for every command to be sent to a switch, it does "expect Cisco prompt *# then send commands in list line by line, with newline at the end".

Now I would like to use a variable previously set in the script (like: set ip "192.168.2.2") inside the command file, like this:

 cat commands.txt
  configure terminal
  Interface Vlan10
  ip address $ip 255.255.255.0

how can I do that?

Now, the variable gets ignored and obviously gets sent as literal string. eg:

ip address $ip 255.255.255.0

thanks

Solution

  • Use the subst command: https://www.tcl.tk/man/tcl8.6/TclCmd/subst.htm

    It performs all the usual string interpolations like $ for variable substitutions and [] for command substitutions and \ for backslash substitutions.

    You can limit it to variable substitution only by using the right argument:

    send "[subst -nocommand -nobackslashes $cmd]\n"