check_env check_env will take the environmental variable ${env_env} and see if its value is a file that bat can read. If not it will try to make a guess as to what would be readable. If the file exist, check_env will make up a pipe command to uncompress, or unzit it if necessary. If not, check_env, will see if ${env_var} has been compressed or zipped, in which case it will make up the pipe command for bat to read it. If none of the above is true, check_env does nothing.