How to check if my SSL certificate is SHA2 ?

Simply run this command, replace example.crt with your actual certificate file:

$ openssl x509 -noout -text -in example.crt

Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number:
            ..
        Signature Algorithm: sha256WithRSAEncryption
        Issuer: C=GB, ST=Greater Manchester, L=Salford, O=COMODO CA Limited, CN=COMODO RSA Domain Validation Secure Server CA
        Validity
            Not Before: Sep 10 00:00:00 2014 GMT
            Not After : Sep 10 23:59:59 2015 GMT