用OpenSSL即可。

查看本地证书文件内容

$ openssl x509 -text -noout -in fly2x.cer

Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number:
            03:ea:ec:f0:de:ff:3d:b3:a8:7f:88:24:7d:61:c1:6a:54:3d
    Signature Algorithm: sha256WithRSAEncryption
        Issuer: C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
        Validity
            Not Before: Aug  7 06:39:05 2020 GMT
            Not After : Nov  5 06:39:05 2020 GMT
        Subject: CN=fly2x.cn
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (2048 bit)
                Modulus:
                    00:d9:44:17:46:17:cb:97:73:02:1f:7a:c2:15:01:
                    c6:d2:94:fd:04:fa:35:13:7f:18:a0:cb:be:91:d4:
                    6c:c9:f2:5a:a6:a2:98:b6:ea:1b:8e:17:5b:24:88:
                    a1:73:14:ac:5b:db:e3:be:af:16:e6:39:dc:80:7c:
                    23:33:ab:76:2d:e5:a7:92:6e:88:c6:6a:a3:cd:b5:
                    20:4e:7f:2d:b3:bb:c5:64:1c:c4:ed:24:e5:c9:9e:
                    95:aa:21:2d:10:1a:8e:9a:6e:1e:db:e8:f0:49:4e:
                    7b:8a:0b:d9:a7:17:fc:f4:b5:df:0c:31:e3:22:31:
                    e9:4d:58:a0:83:ae:16:aa:58:10:e0:a4:f5:3a:f1:
                    e7:41:9a:5f:d2:5f:b7:3b:3a:a6:03:f5:99:2b:a3:
                    0f:4d:1f:8a:fa:56:d4:0d:5c:e1:31:bb:8f:56:df:
                    f6:4c:b9:1d:a1:ee:ec:57:c3:60:c0:06:4a:d6:68:
                    67:1d:5d:ba:25:ca:3f:13:39:8a:4b:10:8b:d7:22:
                    af:da:3a:18:39:aa:4f:b0:90:fb:be:66:04:cb:01:
                    ac:e6:45:bd:e9:3e:a5:8b:cf:a8:ce:15:1c:51:f7:
                    1c:cd:43:6a:7c:4e:5b:2f:06:15:6c:cf:91:7a:64:
                    d3:93:4e:c7:72:d2:1a:41:b3:cd:07:d3:39:12:be:
                    b8:4f
                Exponent: 65537 (0x10001)
        X509v3 extensions:
            X509v3 Key Usage: critical
                Digital Signature, Key Encipherment
            X509v3 Extended Key Usage: 
                TLS Web Server Authentication, TLS Web Client Authentication
            X509v3 Basic Constraints: critical
                CA:FALSE
            X509v3 Subject Key Identifier: 
                D5:C8:5B:4E:5F:AA:E5:FF:A0:83:7F:2B:E5:23:FD:B2:E4:59:98:58
            X509v3 Authority Key Identifier: 
                keyid:A8:4A:6A:63:04:7D:DD:BA:E6:D1:39:B7:A6:45:65:EF:F3:A8:EC:A1

            Authority Information Access: 
                OCSP - URI:http://ocsp.int-x3.letsencrypt.org
                CA Issuers - URI:http://cert.int-x3.letsencrypt.org/

            X509v3 Subject Alternative Name: 
                DNS:*.fly2x.cn, DNS:*.fly2x.com, DNS:fly2x.cn, DNS:fly2x.com
            X509v3 Certificate Policies: 
                Policy: 2.23.140.1.2.1
                Policy: 1.3.6.1.4.1.44947.1.1.1
                  CPS: http://cps.letsencrypt.org

            CT Precertificate SCTs: 
                Signed Certificate Timestamp:
                    Version   : v1(0)
                    Log ID    : F0:95:A4:59:F2:00:D1:82:40:10:2D:2F:93:88:8E:AD:
                                4B:FE:1D:47:E3:99:E1:D0:34:A6:B0:A8:AA:8E:B2:73
                    Timestamp : Aug  7 07:39:05.710 2020 GMT
                    Extensions: none
                    Signature : ecdsa-with-SHA256
                                30:44:02:20:67:D0:C8:CF:96:36:A0:8A:98:B4:BA:F2:
                                98:BF:F2:6A:36:FC:40:C3:E2:6B:28:64:1F:6A:08:85:
                                C2:5E:7E:90:02:20:03:16:7E:FB:CA:2A:15:99:56:6C:
                                B4:A7:E3:F6:F0:2C:C5:28:36:1F:67:67:48:45:1F:35:
                                A4:74:60:B9:C5:78
                Signed Certificate Timestamp:
                    Version   : v1(0)
                    Log ID    : B2:1E:05:CC:8B:A2:CD:8A:20:4E:87:66:F9:2B:B9:8A:
                                25:20:67:6B:DA:FA:70:E7:B2:49:53:2D:EF:8B:90:5E
                    Timestamp : Aug  7 07:39:05.711 2020 GMT
                    Extensions: none
                    Signature : ecdsa-with-SHA256
                                30:46:02:21:00:CB:D5:1A:14:67:8B:50:23:E3:36:65:
                                A9:74:CF:45:43:08:08:C6:2C:13:05:E8:6C:6E:4F:73:
                                F4:CF:37:FC:0B:02:21:00:D8:9E:EB:74:40:10:4E:59:
                                4A:96:47:FD:B1:7A:4F:93:F9:5F:38:84:B3:97:54:42:
                                7F:39:F4:CD:A8:F5:4F:87
    Signature Algorithm: sha256WithRSAEncryption
         1e:5c:88:a9:5a:94:0e:b1:44:58:28:98:a8:cb:85:41:13:e5:
         c0:55:4b:88:85:47:c6:f2:37:62:ff:75:1c:ee:ff:5f:cf:12:
         c3:19:9b:b5:6c:ee:82:2a:1a:b3:3d:6f:2a:e9:33:22:8b:29:
         c2:c6:ff:8b:b9:63:48:55:33:bf:0a:91:c1:db:68:68:95:ee:
         38:c8:6b:9a:95:9c:5f:1d:0d:de:71:e4:97:22:ce:89:45:44:
         c2:94:ea:69:9a:0e:f5:1c:25:6d:0b:3e:1c:fe:af:0b:99:13:
         c0:7c:a5:f9:e7:36:47:a7:ee:2d:98:12:67:07:84:e3:42:48:
         94:d8:0e:38:dc:f5:8a:4c:e8:8d:6e:e7:b6:96:bd:d7:ff:93:
         1b:ae:f8:67:c3:11:7e:aa:45:fe:4e:53:44:5a:50:89:e3:77:
         b8:cb:c5:e5:e9:16:3a:86:6d:fa:57:90:59:9f:29:d3:5c:1d:
         48:48:7a:09:9a:10:34:3e:5f:e0:d4:d9:8a:90:87:62:2d:00:
         12:23:2d:43:a0:73:aa:6a:07:93:1b:99:de:bb:ba:77:51:90:
         31:f8:a5:13:fe:69:bc:7e:85:dc:40:4d:26:51:97:f2:4e:4d:
         41:d2:d7:72:30:a4:d7:ed:ec:ad:bf:99:22:c6:2f:62:dc:fb:
         0b:f4:50:1f