FreeBSD里使用CBSD创建了一个jail， jail里面pkg 命令可以用，但是不管发什么命令，都会提示更新pkg，按Y确认更新，
更新完之后就退出。
再发pkg命令，又是同样提示更新pkg，导致无法pkg search ，无法pkg update，更无法pkg install git
使用ports安装
cd /usr/ports/ports-mgmt/pkg && make install
报错：
===> Installing for pkg-1.21.3
===> Checking if pkg is already installed
===> pkg-1.21.3 is already installed
You may wish to ``make deinstall'' and install this port again
by ``make reinstall'' to upgrade it properly.
If you really wish to overwrite the old port of pkg
without deleting it first, set the variable "FORCE_PKG_REGISTER"
in your environment or the "make install" command line.
*** Error code 1
按照提示输入
make deinstall ; make reinstall还是报错已经安装了pkg
这时候再执行pkg install git ，哇，竟然成功了！所以大约算是用源码编译安装的方法解决了问题。
另外可以在宿主机通过jexec指令来执行jail子系统里的pkg命令，比如
jexec fb12 pkg search wget
pkg: No SRV record found for the repo 'FreeBSD'
wget-1.24.5 Retrieve files from the Net via HTTP(S) and FTP
wget2-2.1.0_1 File and recursive website downloader
wgetpaste-2.34 Paste to several pastebin services via bash script