问题1：

// GCC编译莫名其妙的报错

guang@guang-ubuntu:~/Develop/trainning/liguang/trainning/netApp$ gcc hello_server.c hello_server.c -o hello_server 

/tmp/ccdVr3CQ.o: In function `main': 

hello_server.c:(.text+0x0): multiple definition of `main' 

/tmp/ccrChpRi.o:hello_server.c:(.text+0x0): first defined here 

/tmp/ccdVr3CQ.o: In function `error_handling': 

hello_server.c:(.text+0x187): multiple definition of `error_handling' 

/tmp/ccrChpRi.o:hello_server.c:(.text+0x187): first defined here 

collect2: error: ld returned 1 exit status 

guang@guang-ubuntu:~/Develop/trainning/liguang/trainning/netApp$ gcc hello_server.c hello_server.c -o hello_server -pthread 

/tmp/ccOzaoLV.o: In function `main': 

hello_server.c:(.text+0x0): multiple definition of `main' 

/tmp/cc8UnZv4.o:hello_server.c:(.text+0x0): first defined here 

/tmp/ccOzaoLV.o: In function `error_handling': 

hello_server.c:(.text+0x187): multiple definition of `error_handling' 

/tmp/cc8UnZv4.o:hello_server.c:(.text+0x187): first defined here 

collect2: error: ld returned 1 exit status

// arm交叉编译器是好的，奇怪

guang@guang-ubuntu:~/Develop/trainning/liguang/trainning/netApp$ arm-linux-gnueabi-gc 

arm-linux-gnueabi-gcc           arm-linux-gnueabi-gcc-ar-7      arm-linux-gnueabi-gcc-ranlib    arm-linux-gnueabi-gcov-7        arm-linux-gnueabi-gcov-tool     

arm-linux-gnueabi-gcc-7         arm-linux-gnueabi-gcc-nm        arm-linux-gnueabi-gcc-ranlib-7  arm-linux-gnueabi-gcov-dump     arm-linux-gnueabi-gcov-tool-7   

arm-linux-gnueabi-gcc-ar        arm-linux-gnueabi-gcc-nm-7      arm-linux-gnueabi-gcov          arm-linux-gnueabi-gcov-dump-7   

guang@guang-ubuntu:~/Develop/trainning/liguang/trainning/netApp$ arm-linux-gnueabi-gcc hello_server.c -o hello_server 

guang@guang-ubuntu:~/Develop/trainning/liguang/trainning/netApp$ ls 

hello_server  hello_server.c 

guang@guang-ubuntu:~/Develop/trainning/liguang/trainning/netApp$ gcc 

gcc           gcc-7         gcc-ar        gcc-ar-7      gcc-nm        gcc-nm-7      gcc-ranlib    gcc-ranlib-7  

// gcc-7是好的

guang@guang-ubuntu:~/Develop/trainning/liguang/trainning/netApp$ gcc-7 hello_server.c -o hello_server

// 现在换gcc又好了，莫名其妙

guang@guang-ubuntu:~/Develop/trainning/liguang/trainning/netApp$ gcc hello_server.c -o hello_server 

guang@guang-ubuntu:~/Develop/trainning/liguang/trainning/netApp$ ls hello_server  

hello_server.c 

guang@guang-ubuntu:~/Develop/trainning/liguang/trainning/netApp$ rm hello_server 

guang@guang-ubuntu:~/Develop/trainning/liguang/trainning/netApp$ ls 

hello_server.c 

guang@guang-ubuntu:~/Develop/trainning/liguang/trainning/netApp$ gcc hello_server.c -o hello_server 

guang@guang-ubuntu:~/Develop/trainning/liguang/trainning/netApp$ ls 

hello_server  hello_server.c 

guang@guang-ubuntu:~/Develop/trainning/liguang/trainning/netApp$ 

 // gcc升级的时候有报错

guang@guang-ubuntu:~/Develop/trainning/liguang/trainning/netApp$ sudo apt install gcc 

[sudo] password for guang: 

Reading package lists... Done 

Building dependency tree       

Reading state information... Done 

gcc is already the newest version (4:7.3.0-3ubuntu2).

0 upgraded, 0 newly installed, 0 to remove and 81 not upgraded.

1 not fully installed or removed. 

After this operation, 0 B of additional disk space will be used. 

Do you want to continue? [Y/n] y 

Setting up initramfs-tools (0.130ubuntu3) ... 

update-initramfs: deferring update (trigger activated) 

Processing triggers for initramfs-tools (0.130ubuntu3) ... 

update-initramfs: Generating /boot/initrd.img-4.15.0-23-generic 

 gzip: stdout: No space left on device   //这里好像很关键

E: mkinitramfs failure cpio 141 gzip 1

update-initramfs: failed for /boot/initrd.img-4.15.0-23-generic with 1.

dpkg: error processing package initramfs-tools (--configure): 

 installed initramfs-tools package post-installation script subprocess returned error exit status 1

Errors were encountered while processing: 

 initramfs-tools 

E: Sub-process /usr/bin/dpkg returned an error code (1)

问题2：

guang@guang-ubuntu:~/Develop/trainning/liguang/trainning/netApp$ gcc error_handle.c 

/usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o: In function `_start': 

(.text+0x20): undefined reference to `main'

collect2: error: ld returned 1 exit status