expect: Parse variables from stdin

Question

I am running an expect script that will generate some dynamic input coming from stdin .

Is there a way/pattern that addresses the concept of reading from the stdin and storing (?) somewhere the relevant input to be processed/parsed in a latter step?

example :

./myexpectscript.sh arg1 arg2 ..

Running command with id 9494
Running command with id 9494
Running command with id 9494
Running command with id 9494
Command execution finished

I actually want to store the above id, 9494 .

The script actually runs an api call to a remote server and has a duration of several seconds (for what that matters).

edit : the following snippet does not seem to resolve the issue:

expect -re Running command with id [0-9]+

set output \$expect_out(1,string)

as it gives me an error:

invalid command name "0-9"
    while executing
"0-9"
    invoked from within
"expect -re Running command with id [0-9]+"
    (file "./myexpectscript.sh" line 17)

have also tried it with quotes, ie

expect -re "Running command with id [0-9]+"

Answer 1

Use {...} to define your regex, use \\d for decimal number, and capture the string with (...) .

Set a variable with the captured string with $expect_out .

expect -re {Running command with id (\d+)} {
    set cmd_id $expect_out(1,string)
}
puts $cmd_id