Reference to a bash variable whose name contains dot

Question

I have a bash variable: agent1.ip with 192.168.100.137 as its value. When I refer to it in echo like this:

echo $agent         


        

Answer 1

Since bash.ip is not a valid identifier in bash, the environment string bash.ip=192.168.100.37 is not used to create a shell variable on shell startup.

I would use awk, a standard tool, to extract the value from the environment.

bash_ip=$(awk 'BEGIN {print ENVIRON["bash.ip"]}')

Answer 2

Is your code nested, and using functions or scripts that use ksh?

Dotted variable names are an advanced feature in ksh93. A simple case is

$ a=1
$ a.b=123
$ echo ${a.b}
123
$ echo $a
1

If you first attempt to assign to a.b, you'll get

 -ksh: a.b=123: no parent

IHTH

Answer 3

Bash itself doesn't understand variable names with dots in them, but that doesn't mean you can't have such a variable in your environment. Here's an example of how to set it and get it all in one:

env 'agent1.ip=192.168.100.137' bash -c 'env | grep ^agent1\\.ip= | cut -d= -f2-'

Answer 4

Try this:

export myval=`env | grep agent1.port | awk -F'=' '{print $2}'`;echo $myval

Answer 5

The cleanest solution is:

echo path.data | awk '{print ENVIRON[$1]}'