Solve problems encountered when compiling mosquitto

There are four problems ：

1. Can't find cJSON.h
2. Can't find -lcjson
3. make: xsltproc: Command not found
4. I/O error : Attempt to load network entity http://docbook.sourceforge.net/release/xsl/current/manpages/docbook.xsl

• problem 1： Can't find cJSON.h
  Need to download cjson Source code , You can go to github download ：
  https://github.com/DaveGamble/cJSON
  And then use git clone Download it .

But still in config.mk In the CFLAGS Add the download just now cjson The path of , such gcc Can we find . We'll talk about that later .

• problem 2： Can't find -lcjson
  without libcjson.a perhaps libcjson.so, Then compile a , Compile command ：

gcc -c -fPIC cJSON.c -o cjson.o
ar -cr libcjson.a cjson.o

If you want to compile so file , take ar The command is replaced by ：

gcc -shared -o libcjson.so cjson.o

Then we should config.mk Medium CFLAGS and LDFLAGS add -I and -L, Appoint cJSON.h and libcjson.a The path of . The specific path depends on cjson Depends on the download path , For example, mine is ：

CFLAGS+=-I/home/mokar/work/proj/pf/obu/cv2x_obu/mocar/lib/imx6/cJSON
LDFLAGS?=-L/home/mokar/work/proj/pf/obu/cv2x_obu/mocar/lib/imx6/cJSON

meanwhile , By the way config.mk add DESTDIR The path of , If you don't specify DESTDIR The path of , Default install to /usr/local below , If you don't want to install here , It's just config.mk In Chinese, it means DESTDIR Specify a path ：

DESTDIR=/home/mokar/work/lib/mosquitto/mosquitto/target

• problem 3： Can't find xsltproc
• problem 4： Can't download docbook.xsl
  Questions 3 and 4 , Execute the following command ：

sudo apt-get install xsltproc docbook-xsl docbook-xml

Reference to the original link https://blog.csdn.net/weixin_30325793/article/details/99148948