解决nvm导致terminal打开慢的问题

电脑上是使用nvm安装的node，安装之后每次打开一个新的terminal都比较慢，运营是因为termainl在打开的时候会加载nvm相关内容，如下：

# nvm
export NVM_DIR="$HOME/.nvm"
[ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh"  # This loads nvm
[ -s "$NVM_DIR/bash_completion" ] && \. "$NVM_DIR/bash_completion"  # This loads nvm bash_completion

可以按照下面方式来修改，只有在需要用到nvm的时候才去加载：

# nvm
export NVM_DIR="$HOME/.nvm"
#[ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh"  # This loads nvm
#[ -s "$NVM_DIR/bash_completion" ] && \. "$NVM_DIR/bash_completion"  # This loads nvm bash_completion
function _install_nvm() {
  unset -f nvm
  [ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh" # This sets up nvm
  [ -s "$NVM_DIR/bash_completion" ] && \. "$NVM_DIR/bash_completion"  # load nvm bash_completion
  nvm "$@"
}

function nvm() {
    _install_nvm "$@"
}