Put the following file into ~./script/ and then add

source <home>/.script/conda_auto_env.py

bash shell:

#!/bin/bash
#
# auto-env automatically activates a conda environment when
# entering a folder with an environment.yml file.
#
# If the environment doesn't exist, conda-auto-env creates it and
# activates it for you.
#
# To install add this line to your .bashrc or .bash-profile:
#
#       source /path/to/conda_auto_env.sh
#


function conda_auto_env() {
  if [ -e "environment.yml" ]; then
    # echo "environment.yml file found"
    ENV=$(head -n 1 environment.yml | cut -f2 -d ' ')
    # Check if you are already in the environment
    if [[ $PATH != *$ENV* ]]; then
      # Check if the environment exists
      conda activate $ENV
      if [ $? -eq 0 ]; then
      :
      else
        # Create the environment and activate
        echo "Conda env '$ENV' doesn't exist."
        conda env create -q
        source activate $ENV
      fi
    fi
  fi
}

export PROMPT_COMMAND=conda_auto_env

zsh:

#!/bin/zsh

# conda-auto-env automatically activates a conda environment when
# entering a folder with an environment.yml file.
#
# If the environment doesn't exist, conda-auto-env creates it and
# activates it for you.
#
# To install add this line to your .bashrc or .bash-profile:
#
#       source /path/to/conda_auto_env.sh
#

function conda_auto_env() {
  if [ -e "environment.yml" ]; then
    # echo "environment.yml file found"
    ENV=$(head -n 1 environment.yml | cut -f2 -d ' ')
    # Check if you are already in the environment
    if [[ $PATH != *$ENV* ]]; then
      # Check if the environment exists
      conda activate $ENV
      if [ $? -eq 0 ]; then
        :
      else
        # Create the environment and activate
        echo "Conda env '$ENV' doesn't exist."
        conda env create -q
        source activate $ENV
      fi
    fi
  fi
}

precmd() { eval conda_auto_env }

Reference

https://github.com/chdoig/conda-auto-env/blob/master/conda_auto_env.sh