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Full Discussion: Variable within variable expansion
Top Forums Shell Programming and Scripting Variable within variable expansion Post 303044728 by hburnswell on Monday 2nd of March 2020 04:15:37 PM
Old 03-02-2020
Variable within variable expansion
Hi,

I have been trying to get variable within variable expansion to work but have not been able to succeed. It seems that the two suggestions I am seeing are using 'eval' and using the built in bash capability of "${!test}". Here is a snippet of what I"m trying to accomplish:

Code:
#!/bin/bash
b2b_qa_site=1234
b2c_qa_site=4321
b2b_prd_site=5678
b2c_prd_site=8765

grp=`echo "${1: -2:1}"`
env=`echo "${1: -3:1}"`


if [[ $env -eq 4 ]]; then

        env=prd

else

        env=qa

fi

if [[ $grp -eq 0 ]]; then

        grp=b2b

else

        grp=b2c

fi

test=${grp}_${env}_site
eval echo \$test

This would be used as:

Code:
# ./script box400

And ideally receive:

Code:
5678

Can anyone shed some light on what I am doing wrong here? I appreciate any guidance.

Thanks,
HB
 

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LEARN ABOUT DEBIAN

rabbitmq-env.conf

RABBITMQ-ENV.CONF(5)						  RabbitMQ Server					      RABBITMQ-ENV.CONF(5)

NAME

       rabbitmq-env.conf - default settings for RabbitMQ AMQP server

DESCRIPTION

       /etc/rabbitmq/rabbitmq-env.conf contains variable settings that override the defaults built in to the RabbitMQ startup scripts.

       The file is interpreted by the system shell, and so should consist of a sequence of shell environment variable definitions. Normal shell
       syntax is permitted (since the file is sourced using the shell "." operator), including line comments starting with "#".

       In order of preference, the startup scripts get their values from the environment, from /etc/rabbitmq/rabbitmq-env.conf and finally from
       the built-in default values. For example, for the RABBITMQ_NODENAME setting,

       RABBITMQ_NODENAME

       from the environment is checked first. If it is absent or equal to the empty string, then

       NODENAME

       from /etc/rabbitmq/rabbitmq-env.conf is checked. If it is also absent or set equal to the empty string then the default value from the
       startup script is used.

       The variable names in /etc/rabbitmq/rabbitmq-env.conf are always equal to the environment variable names, with the RABBITMQ_ prefix
       removed: RABBITMQ_NODE_PORT from the environment becomes NODE_PORT in the /etc/rabbitmq/rabbitmq-env.conf file, etc.

       # I am a complete /etc/rabbitmq/rabbitmq-env.conf file.
       # Comment lines start with a hash character.
       # This is a /bin/sh script file - use ordinary envt var syntax
       NODENAME=hare

SEE ALSO

       rabbitmq-server(1) rabbitmqctl(1)

EXAMPLES

       # I am a complete /etc/rabbitmq/rabbitmq-env.conf file.
       # Comment lines start with a hash character.
       # This is a /bin/sh script file - use ordinary envt var syntax
       NODENAME=hare

       This is an example of a complete /etc/rabbitmq/rabbitmq-env.conf file that overrides the default Erlang node name from "rabbit" to "hare".

AUTHOR

       The RabbitMQ Team <info@rabbitmq.com>

RabbitMQ Server 						    06/22/2012						      RABBITMQ-ENV.CONF(5)
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