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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 SUNOS

env

env(1)								   User Commands							    env(1)

NAME

       env - set environment for command invocation

SYNOPSIS

       /usr/bin/env [-i | -]  [name=value...] [ utility [ arg... ]]

       /usr/xpg4/bin/env [-i | -]  [name=value...] [ utility [ arg... ]]

DESCRIPTION

       The  env utility obtains the current environment, modifies it according to its arguments, then invokes the utility named by the utility op-
       erand with the modified environment.

       Optional arguments are passed to utility. If no utility operand is specified, the resulting environment is written to the standard  output,
       with one name=value pair per line.

   /usr/bin
       If env executes commands with arguments, it uses the default shell /usr/bin/sh (see sh(1)).

   /usr/xpg4/bin
       If env executes commands with arguments, it uses /usr/xpg4/bin/sh (see ksh(1)).

OPTIONS

       The following options are supported:

       -i | -	       Ignores the environment that would otherwise be inherited from the current shell.  Restricts the environment for utility to
		       that specified by the arguments.

OPERANDS

       The following operands are supported:

       name=value      Arguments of the form name=value modify the execution environment, and are placed into  the  inherited  environment  before
		       utility is invoked.

       utility	       The name of the utility to be invoked.  If utility names any of the special shell built-in utilities, the results are unde-
		       fined.

       arg	       A string to pass as an argument for the invoked utility.

EXAMPLES

       Example 1: Invoking utilities with new PATH values

       The following utility:

       example% env -i PATH=/mybin mygrep xyz myfile

       invokes the utility mygrep with a new PATH value as the only entry in its environment. In this case, PATH is used to locate  mygrep,  which
       then must reside in /mybin.

ENVIRONMENT VARIABLES

       See  environ(5)	for  descriptions of the following environment variables that affect the execution of env: LANG, LC_ALL, LC_CTYPE, LC_MES-
       SAGES, and NLSPATH.

       PATH	Determine the location of the utility. If PATH is specified as a name=value operand to env, the value given shall be used  in  the
		search for utility.

EXIT STATUS

       If  utility  is invoked, the exit status of env is the exit status of utility. Otherwise, the env utility returns one of the following exit
       values:

       0	Successful completion.

       1-125	An error occurred.

       126	utility was found but could not be invoked.

       127	utility could not be found.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

   /usr/bin
       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsu			   |
       +-----------------------------+-----------------------------+
       |CSI			     |enabled			   |
       +-----------------------------+-----------------------------+

   /usr/xpg4/bin
       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWxcu4			   |
       +-----------------------------+-----------------------------+
       |CSI			     |enabled			   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       ksh(1), sh(1), exec(2), profile(4), attributes(5), environ(5), standards(5)

SunOS 5.10							    2 Jan 2002								    env(1)
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