Chapter 12. Send
In this chapter, I will provide more detail about the send
command, including its ability to send strings with special timings between the letters of a string. I will revisit the concepts from the previous two chapters—dealing with multiple processes—in the context of send
. Finally, I will describe some interactions between send
and other parts of Expect such as how to send
without echoing.
The descriptions in this chapter will explicitly refer to the send
command, but most of them apply to the related commands send_user
, send_error
, and send_tty
.
Implicit Versus Explicit Spawn Ids
The previous chapter showed the differences between controlling expect
with spawn_id
versus using the -i
flag. The send
command can be controlled in the same way. For example, the two lines are equivalent—both send the string foo
to the process corresponding to the spawn id in the proc
variable.
set spawn_id $proc; send "foo" send −i $proc "foo"
While the first line is longer, setting the spawn id is simpler if a single process is the focus of interaction for a group of commands. For example, if a login is performed, the implicit method (using spawn_id
) looks like this:
set spawn_id $proc expect "login:" send "$name\r" expect "Password:" send "$password\r" expect "$prompt"
Using explicit −i
parameters requires more characters and is more difficult to read.
expect −i $proc "login:" send −i $proc "$name\r" expect −i $proc "Password:" send −i $proc "$password\r" expect −i $proc "$prompt"
Setting ...
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