If libcurl is already installed, check that 'pkg-config' is in your PATH and PKG_CONFIG_PA

1、R安装devtools过程中遇到如下问题：

> install.packages('devtools', repos='https://mirror.lzu.edu.cn/CRAN/')

2、解决方法

sudo apt-get install libssl-dev
sudo apt-get install libssh2-1-dev
sudo apt-get install libcurl4-openssl-dev
sudo apt-get install libxml2-dev

3、测试

install.packages('devtools', repos='https://mirror.lzu.edu.cn/CRAN/')

参考：https://blog.csdn.net/Wing_kin666/article/details/106020600