Sample openssl config file

openssl.cnf

dir = certificates

[ ca ]
default_ca = CA_default

[ CA_default ]
serial = $dir/serial
database = $dir/index.txt
new_certs_dir = $dir/newcerts
certificate  = $dir/cacert.pem
private_key = $dir/private/cakey.pem
default_days = 36500
default_md  = sha256
preserve = no
email_in_dn  = no
nameopt = default_ca
certopt = default_ca
policy = policy_match

[ policy_match ]
commonName = supplied
countryName = optional
stateOrProvinceName = optional
organizationName = optional
organizationalUnitName = optional
emailAddress = optional

[ req ]
default_bits = 2048
default_keyfile = priv.pem
default_md = sha256
distinguished_name = req_distinguished_name
req_extensions = v3_req
encyrpt_key = no

[ req_distinguished_name ]

[ v3_ca ]
basicConstraints = CA:TRUE
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid:always,issuer:always

[ v3_req ]
basicConstraints = CA:FALSE
subjectKeyIdentifier = hash

Is it possible to use shell commands here to make this dynamic ?

@KishanKishore openssl command does not provide enough command line options for configuration fields, you have to specify most of them in config file