Shell Programming and Scripting

Hello All,

I have embedded some expect code inside a Bash script I'm writing, but for some reason any variable I 'set' to something is
showing as empty immediately on the next line...

I haven't run into this problem before so I'm not sure what it could be...? I'm guessing it has something to do with the code
being embedded in another script..?


Here's my Code:

Code:

#!/bin/bash

echo "Here, in Bash Script"

# other stuff.....:......


/usr/bin/expect - << EOF

    set my_var "Hello World"

    puts "my_var = $my_var\n"

EOF

echo "Back from Expect Script"

exit 0

And my Output:

Code:

Here, in Bash Script
my_var = 

Back from Expect Script

Anyone know why the variables are NOT being set? I'm Stumpped..!!!
Any thoughts would be very much appreciated.


Thanks in Advance,
Matt

---------- Post updated at 04:51 PM ---------- Previous update was at 04:17 PM ----------

Figured it out...!!

You need to escape the '$' in front of any/all variables. I think this is due to using the "<<" which is open to variable expansion, so
I think that's why they need to be escaped...

So if the code is like this, it will work:

Code:

#!/bin/bash

echo "Here, in Bash Script"

# other stuff.....:......


/usr/bin/expect - << EOF

    set my_var "Hello World"

    puts "my_var = \$my_var\n"

EOF

echo "Back from Expect Script"

exit 0

*Notice the '\' in front of "\$my_var" in the puts statement...

And my Output:

Code:

Here, in Bash Script
my_var = Hello World

Back from Expect Script

Hopefully that helps someone in the same predicament I was in...

Thanks,
Matt

Exactly right. The $ gets substituted first, otherwise.

There is also an alternative way:

Code:

<<"EOF"

This kind of here-doc will not substitute, at all.

Hey Corona, thanks for the reply!

Ohh ok, cool... So if you quote the "EOF" then do you not need to escape the '$' for all the variables?


Thanks Again,
Matt

Exactly. (The ending EOF is not in quotes, incidentally.)

The only problem is, if you actually want to substitute anything, you really can't.

Hey Corona, thanks again for the reply!

Yea, that should be fine, I don't think I'll need to do that in there anyway... Its just basically only like 10 lines or so of code, so nothing crazy
going on in there.

Anyway, thanks again for the info, much appreciated!

Thanks,
Matt