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Full Discussion: Expect Script - Variables are Empty immediately after "Setting" Them?
Top Forums Shell Programming and Scripting Expect Script - Variables are Empty immediately after "Setting" Them? Post 302780011 by mrm5102 on Wednesday 13th of March 2013 04:51:24 PM
Old 03-13-2013
Expect Script - Variables are Empty immediately after "Setting" Them?
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
 

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LEARN ABOUT LINUX

bashbug

BASHBUG(1)							      bashbug								BASHBUG(1)

NAME

       bashbug - report a bug in bash

SYNOPSIS

       bashbug [--help] [--version] [bug-report-email-addresses]

DESCRIPTION

       bashbug is a utility for reporting bugs in Bash to the maintainers.

       bashbug will start up your preferred editor with a preformatted bug report template for you to fill in. Save the file and quit the editor
       once you have completed the missing fields.  bashbug will notify you of any problems with the report and ask for confirmation before
       sending it. By default the bug report is mailed to both the GNU developers and the Debian Bash maintainers. The recipients can be changed
       by giving a comma separated list of bug-report-email-addresses.

       If you invoke bashbug by accident, just quit your editor. You will always be asked for confirmation before a bug report is sent.

OPTIONS

       --help
	      Show a brief usage message and exit.

       --version
	      Show the version of bashbug and exit.

       bug-report-email-addresses
	      Comma separated list of recipients' email addresses. By default the report is mailed to both the GNU developers and the Debian Bash
	      maintainers.

ENVIRONMENT

       DEFEDITOR
	      Editor to use for editing the bug report.

       EDITOR
	      Editor to use for editing the bug report (overridden by DEFEDITOR).

SEE ALSO

       bash(1), reportbug(1), update-alternatives(8) for preferred editor.

AUTHOR

       This manual page was written by Christer Andersson <klamm@comhem.se> for the Debian project (but may be used by others).

GNU Bash 3.1							 11 December 2007							BASHBUG(1)
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