为了学习使用AppJail，升级FreeBSD，从14.1-BETA3升级到14.1-RELEASE
当前最新的发布版本是14.1-RELEASE，所以upgrade后面跟了-r 版本号。
使用命令freebsd-update upgrade -r 14.1-RELEASE：
freebsd-update upgrade -r 14.1-RELEASE执行后显示：
The following components of FreeBSD seem to be installed:
kernel/generic kernel/generic-dbg world/base world/lib32
The following components of FreeBSD do not seem to be installed:
world/base-dbg world/lib32-dbg
Does this look reasonable (y/n)? y
按y继续
Preparing to download files...
这里稍微等了一会儿，反而后面fetch的很快。
Fetching 1786 patches 很快，但是fetch files就很慢了：
Fetching 1782 files
最后显示：
The following files will be updated as part of updating to
14.1-RELEASE-p0:
/bin/freebsd-version
/boot/boot1.efi
/boot/kernel/aac.ko
.....
/boot/kernel/g_audio.ko
To install the downloaded upgrades, run 'freebsd-update [options] install'.
这样freebsd-update upgrade -r 14.1-RELEASE这条指令就完成了，按照提示执行freebsd-update install：
freebsd-update install
src component not installed, skipped
Creating snapshot of existing boot environment... done.
Installing updates...
Kernel updates have been installed. Please reboot and run
'freebsd-update [options] install' again to finish installing updates.
完成后按照提示重启服务器。
重启后再次执行freebsd-update install :
freebsd-update install
src component not installed, skipped
Creating snapshot of existing boot environment... done.
Installing updates...
Restarting sshd after upgrade
Performing sanity check on sshd configuration.
Stopping sshd.
Waiting for PIDS: 1326.
Performing sanity check on sshd configuration.
Starting sshd.
Scanning /usr/share/certs/untrusted for certificates...
Scanning /usr/share/certs/trusted for certificates...
Scanning /usr/local/share/certs for certificates...done.这样FreeBSD内核就从14.1-BETA3 升级到了14.1-REALEASE
uname -a
FreeBSD fbhost 14.1-RELEASE FreeBSD 14.1-RELEASE releng/14.1-n267679-10e31f0946d8 GENERIC amd64
到这里就升级完成了，整个过程方便又安全，很棒！整个过程大约用了4个小时，主要是网速有点不给力。当然，如果是新机器，直接安装新版本系统会更快！
