https centos6 and 7

keytool -printcert -sslserver 10.10.192.90:8443 -rfc >nexus.crt

通过  openssl 将 证书转换为 .pem格式的

通过以下命令， 转换为  .pem格式

openssl   x509   -in   a.cer   -out   a.pem   

openssl version -d 

get the directory, add the content to the tail of the files.

• AIX, OpenSSL 0.9.6 (from OpenSSH support packages) /var/ssl/
• Centos 3 / 4, OpenSSL 0.9.7 /usr/share/ssl/
• Cygwin, OpenSSL 0.9.6 /usr/ssl/
• Debian Woody (3.0), OpenSSL 0.9.6 /etc/ssl/
• Debian Sarge (3.1), OpenSSL 0.9.7 /etc/ssl/
• Debian Etch (4.0), OpenSSL 0.9.8 /etc/ssl/
• Debian Lenny (5.0), OpenSSL 0.9.8 /etc/ssl/
• Debian Squeeze (6.0), OpenSSL 0.9.8o /etc/ssl/
• FreeBSD, OpenSSL 0.9.8 /etc/ssl/
• FreeBSD, OpenSSL 0.9.x (custom complile) /usr/local/openssl/
• Gentoo, OpenSSL 0.9.6 /usr/lib/ssl/
• Gentoo, OpenSSL 0.9.7 /etc/ssl/
• Mac OS X 10.1.2, OpenSSL 0.9.6b /System/Library/OpenSSL/
• Mandrake 7.1 -> 8.2, OpenSSL 0.9.6 /usr/lib/ssl/
• NetBSD, OpenSSL 0.9.x /etc/openssl/
• Nokia N900 Maemo 5, OpenSSL 0.9.8n /etc/ssl/
• Normal OpenSSL Tarball Build, OpenSSL 0.9.6 /usr/local/ssl/
• OpenBSD, OpenSSL 0.9.x /etc/ssl/
• Redhat 6.2 / 7.x / 8.0 / 9, OpenSSL 0.9.6 /usr/share/ssl/
• Redhat Enterprise 3 / 4, OpenSSL 0.9.7 /usr/share/ssl/
• Redhat Enterprise 6, OpenSSL 1.0.0 /etc/pki/tls/
• Redhat Fedora Core 2 / 3, OpenSSL 0.9.7 /usr/share/ssl/
• Redhat Fedora Core 4, OpenSSL 0.9.7 /etc/pki/tls/
• Redhat Fedora Core 5 / 6, OpenSSL 0.9.8 /etc/pki/tls/
• Slackware, OpenSSL 0.9.6 /etc/ssl/
• SuSE 7.3 / 8.0, OpenSSL 0.9.6 /usr/share/ssl/
• SuSE 8.1 / 8.2, OpenSSL 0.9.6 /etc/ssl/
• Ubuntu Maverick (10.10), OpenSSL 0.9.8o /etc/ssl/
• Ubuntu Precise (12.04), OpenSSL 1.0.1 /etc/ssl/

 centos
---
Install the ca-certificates package:

yum install ca-certificates

Enable the dynamic CA configuration feature:

update-ca-trust enable

Add it as a new file to /etc/pki/ca-trust/source/anchors/:

cp foo.crt /etc/pki/ca-trust/source/anchors/

Use command:

update-ca-trust extract