I am hoping to run a simple shell script to ease the management around some conda environments.  Activating conda environments via conda activate in a linux os works fine in the shell but is problematic within a shell script.  Could someone point me into the right direction as to why this is happening?
Example to repeat the issue:
# default conda env
$ conda info | egrep "conda version|active environment"
     active environment : base
          conda version : 4.6.9
# activate new env to prove that it works
$ conda activate scratch
$ conda info | egrep "conda version|active environment"
     active environment : scratch
          conda version : 4.6.9
# revert back to my original conda env
$ conda activate base 
$ cat shell_script.sh
#!/bin/bash
conda activate scratch
# run shell script - this will produce an error even though it succeeded above
$ ./shell_script.sh
CommandNotFoundError: Your shell has not been properly configured to use 'conda activate'.
To initialize your shell, run
    $ conda init <SHELL_NAME>
Currently supported shells are:
  - bash
  - fish
  - tcsh
  - xonsh
  - zsh
  - powershell
See 'conda init --help' for more information and options.
IMPORTANT: You may need to close and restart your shell after running 'conda init'.