Go的基本使用
本文用于记录学习Golang相关知识点。
Go编程语言中文文档中介绍Go:
Go编程语言是一个开源项目，它使程序员更具生产力。
Go语言具有很强的表达能力，它简洁、清晰而高效。得益于其并发机制，用它编写的程序能够非常有效地利用多核与联网的计算机，其新颖的类型系统则使程序结构变得灵活而模块化。Go代码编译成机器码不仅非常迅速，还具有方便的垃圾收集机制和强大的运行时反射机制。 它是一个快速的、静态类型的编译型语言，感觉却像动态类型的解释型语言。
我们可以简单的理解Go语言解决了其他语言并发执行的痛点，像C语言一样的运行效率高，又兼容了Python语言的开发速度快的特点，Go = C + Python, Go语言被称为"互联网时代的C"。我们不在概念上过多的纠结，直接来开始使用Go这门编程语言。
0. 特别说明
- 本文档中
Golang简写为Go。 - 本文档假定您会使用Linux操作系统的基本命令，如vim、cat、ls等一些工具。
Go学习网站：官方文档https://golang.google.cn/doc/Go学习网站：Go编程语言中文文档https://go-zh.org/doc/Go学习网站：Go语言之旅https://go-tour-zh.appspot.com/listGo学习网站：实效Go编程https://go-zh.org/doc/effective_go.htmlGo学习网站：Go编程语言规范https://go-zh.org/ref/spec
1. 实验环境
本实验使用CentOS7.9作为实验环境。
sh
[root@hellogitlab ~]# cat /etc/centos-release
CentOS Linux release 7.9.2009 (Core)安装go前先配置yum源：
sh
[root@hellogitlab ~]# curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-7.repo
[root@hellogitlab ~]# curl -o /etc/yum.repos.d/epel.repo https://mirrors.aliyun.com/repo/epel-7.repo2. 安装和配置GO环境
2.1 安装Golang
- 使用
yum install go -y安装Golang。
sh
[root@hellogitlab ~]# yum install go -y
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: mirrors.aliyuncs.com
* extras: mirrors.aliyuncs.com
* updates: mirrors.aliyuncs.com
Resolving Dependencies
--> Running transaction check
---> Package golang.x86_64 0:1.20.12-1.el7 will be installed
--> Processing Dependency: golang-bin = 1.20.12-1.el7 for package: golang-1.20.12-1.el7.x86_64
--> Processing Dependency: golang-src = 1.20.12-1.el7 for package: golang-1.20.12-1.el7.x86_64
--> Processing Dependency: openssl-devel for package: golang-1.20.12-1.el7.x86_64
--> Running transaction check
---> Package golang-bin.x86_64 0:1.20.12-1.el7 will be installed
--> Processing Dependency: /usr/bin/gcc for package: golang-bin-1.20.12-1.el7.x86_64
---> Package golang-src.noarch 0:1.20.12-1.el7 will be installed
---> Package openssl-devel.x86_64 1:1.0.2k-26.el7_9 will be installed
--> Processing Dependency: openssl-libs(x86-64) = 1:1.0.2k-26.el7_9 for package: 1:openssl-devel-1.0.2k-26.el7_9.x86_64
--> Processing Dependency: zlib-devel(x86-64) for package: 1:openssl-devel-1.0.2k-26.el7_9.x86_64
--> Processing Dependency: krb5-devel(x86-64) for package: 1:openssl-devel-1.0.2k-26.el7_9.x86_64
--> Running transaction check
---> Package gcc.x86_64 0:4.8.5-44.el7 will be installed
--> Processing Dependency: cpp = 4.8.5-44.el7 for package: gcc-4.8.5-44.el7.x86_64
--> Processing Dependency: glibc-devel >= 2.2.90-12 for package: gcc-4.8.5-44.el7.x86_64
--> Processing Dependency: libmpfr.so.4()(64bit) for package: gcc-4.8.5-44.el7.x86_64
--> Processing Dependency: libmpc.so.3()(64bit) for package: gcc-4.8.5-44.el7.x86_64
---> Package krb5-devel.x86_64 0:1.15.1-55.el7_9 will be installed
--> Processing Dependency: libkadm5(x86-64) = 1.15.1-55.el7_9 for package: krb5-devel-1.15.1-55.el7_9.x86_64
--> Processing Dependency: krb5-libs(x86-64) = 1.15.1-55.el7_9 for package: krb5-devel-1.15.1-55.el7_9.x86_64
--> Processing Dependency: libverto-devel for package: krb5-devel-1.15.1-55.el7_9.x86_64
--> Processing Dependency: libselinux-devel for package: krb5-devel-1.15.1-55.el7_9.x86_64
--> Processing Dependency: libcom_err-devel for package: krb5-devel-1.15.1-55.el7_9.x86_64
--> Processing Dependency: keyutils-libs-devel for package: krb5-devel-1.15.1-55.el7_9.x86_64
---> Package openssl-libs.x86_64 1:1.0.2k-19.el7 will be updated
--> Processing Dependency: openssl-libs(x86-64) = 1:1.0.2k-19.el7 for package: 1:openssl-1.0.2k-19.el7.x86_64
---> Package openssl-libs.x86_64 1:1.0.2k-26.el7_9 will be an update
---> Package zlib-devel.x86_64 0:1.2.7-21.el7_9 will be installed
--> Processing Dependency: zlib = 1.2.7-21.el7_9 for package: zlib-devel-1.2.7-21.el7_9.x86_64
--> Running transaction check
---> Package cpp.x86_64 0:4.8.5-44.el7 will be installed
---> Package glibc-devel.x86_64 0:2.17-326.el7_9.3 will be installed
--> Processing Dependency: glibc-headers = 2.17-326.el7_9.3 for package: glibc-devel-2.17-326.el7_9.3.x86_64
--> Processing Dependency: glibc = 2.17-326.el7_9.3 for package: glibc-devel-2.17-326.el7_9.3.x86_64
--> Processing Dependency: glibc-headers for package: glibc-devel-2.17-326.el7_9.3.x86_64
---> Package keyutils-libs-devel.x86_64 0:1.5.8-3.el7 will be installed
---> Package krb5-libs.x86_64 0:1.15.1-50.el7 will be updated
---> Package krb5-libs.x86_64 0:1.15.1-55.el7_9 will be an update
---> Package libcom_err-devel.x86_64 0:1.42.9-19.el7 will be installed
---> Package libkadm5.x86_64 0:1.15.1-55.el7_9 will be installed
---> Package libmpc.x86_64 0:1.0.1-3.el7 will be installed
---> Package libselinux-devel.x86_64 0:2.5-15.el7 will be installed
--> Processing Dependency: libsepol-devel(x86-64) >= 2.5-10 for package: libselinux-devel-2.5-15.el7.x86_64
--> Processing Dependency: pkgconfig(libsepol) for package: libselinux-devel-2.5-15.el7.x86_64
--> Processing Dependency: pkgconfig(libpcre) for package: libselinux-devel-2.5-15.el7.x86_64
---> Package libverto-devel.x86_64 0:0.2.5-4.el7 will be installed
---> Package mpfr.x86_64 0:3.1.1-4.el7 will be installed
---> Package openssl.x86_64 1:1.0.2k-19.el7 will be updated
---> Package openssl.x86_64 1:1.0.2k-26.el7_9 will be an update
---> Package zlib.x86_64 0:1.2.7-18.el7 will be updated
---> Package zlib.x86_64 0:1.2.7-21.el7_9 will be an update
--> Running transaction check
---> Package glibc.x86_64 0:2.17-317.el7 will be updated
--> Processing Dependency: glibc = 2.17-317.el7 for package: glibc-common-2.17-317.el7.x86_64
---> Package glibc.x86_64 0:2.17-326.el7_9.3 will be an update
---> Package glibc-headers.x86_64 0:2.17-326.el7_9.3 will be installed
--> Processing Dependency: kernel-headers >= 2.2.1 for package: glibc-headers-2.17-326.el7_9.3.x86_64
--> Processing Dependency: kernel-headers for package: glibc-headers-2.17-326.el7_9.3.x86_64
---> Package libsepol-devel.x86_64 0:2.5-10.el7 will be installed
---> Package pcre-devel.x86_64 0:8.32-17.el7 will be installed
--> Running transaction check
---> Package glibc-common.x86_64 0:2.17-317.el7 will be updated
---> Package glibc-common.x86_64 0:2.17-326.el7_9.3 will be an update
---> Package kernel-headers.x86_64 0:3.10.0-1160.119.1.el7 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
===============================================================================================================================================================================================================================================================================
Package Arch Version Repository Size
===============================================================================================================================================================================================================================================================================
Installing:
golang x86_64 1.20.12-1.el7 epel 673 k
Installing for dependencies:
cpp x86_64 4.8.5-44.el7 base 5.9 M
gcc x86_64 4.8.5-44.el7 base 16 M
glibc-devel x86_64 2.17-326.el7_9.3 updates 1.1 M
glibc-headers x86_64 2.17-326.el7_9.3 updates 692 k
golang-bin x86_64 1.20.12-1.el7 epel 65 M
golang-src noarch 1.20.12-1.el7 epel 12 M
kernel-headers x86_64 3.10.0-1160.119.1.el7 updates 9.1 M
keyutils-libs-devel x86_64 1.5.8-3.el7 base 37 k
krb5-devel x86_64 1.15.1-55.el7_9 updates 273 k
libcom_err-devel x86_64 1.42.9-19.el7 base 32 k
libkadm5 x86_64 1.15.1-55.el7_9 updates 180 k
libmpc x86_64 1.0.1-3.el7 base 51 k
libselinux-devel x86_64 2.5-15.el7 base 187 k
libsepol-devel x86_64 2.5-10.el7 base 77 k
libverto-devel x86_64 0.2.5-4.el7 base 12 k
mpfr x86_64 3.1.1-4.el7 base 203 k
openssl-devel x86_64 1:1.0.2k-26.el7_9 updates 1.5 M
pcre-devel x86_64 8.32-17.el7 base 480 k
zlib-devel x86_64 1.2.7-21.el7_9 updates 50 k
Updating for dependencies:
glibc x86_64 2.17-326.el7_9.3 updates 3.6 M
glibc-common x86_64 2.17-326.el7_9.3 updates 12 M
krb5-libs x86_64 1.15.1-55.el7_9 updates 810 k
openssl x86_64 1:1.0.2k-26.el7_9 updates 494 k
openssl-libs x86_64 1:1.0.2k-26.el7_9 updates 1.2 M
zlib x86_64 1.2.7-21.el7_9 updates 90 k
Transaction Summary
===============================================================================================================================================================================================================================================================================
Install 1 Package (+19 Dependent packages)
Upgrade ( 6 Dependent packages)
Total download size: 131 M
Downloading packages:
Delta RPMs disabled because /usr/bin/applydeltarpm not installed.
(1/26): glibc-2.17-326.el7_9.3.x86_64.rpm | 3.6 MB 00:00:03
(2/26): glibc-devel-2.17-326.el7_9.3.x86_64.rpm | 1.1 MB 00:00:01
(3/26): glibc-headers-2.17-326.el7_9.3.x86_64.rpm | 692 kB 00:00:00
(4/26): golang-1.20.12-1.el7.x86_64.rpm | 673 kB 00:00:00
(5/26): cpp-4.8.5-44.el7.x86_64.rpm | 5.9 MB 00:00:05
(6/26): glibc-common-2.17-326.el7_9.3.x86_64.rpm | 12 MB 00:00:11
(7/26): keyutils-libs-devel-1.5.8-3.el7.x86_64.rpm | 37 kB 00:00:00
(8/26): krb5-devel-1.15.1-55.el7_9.x86_64.rpm | 273 kB 00:00:00
(9/26): krb5-libs-1.15.1-55.el7_9.x86_64.rpm | 810 kB 00:00:00
(10/26): libcom_err-devel-1.42.9-19.el7.x86_64.rpm | 32 kB 00:00:00
(11/26): libkadm5-1.15.1-55.el7_9.x86_64.rpm | 180 kB 00:00:00
(12/26): libmpc-1.0.1-3.el7.x86_64.rpm | 51 kB 00:00:00
(13/26): libselinux-devel-2.5-15.el7.x86_64.rpm | 187 kB 00:00:00
(14/26): libsepol-devel-2.5-10.el7.x86_64.rpm | 77 kB 00:00:00
(15/26): libverto-devel-0.2.5-4.el7.x86_64.rpm | 12 kB 00:00:00
(16/26): mpfr-3.1.1-4.el7.x86_64.rpm | 203 kB 00:00:00
(17/26): openssl-1.0.2k-26.el7_9.x86_64.rpm | 494 kB 00:00:00
(18/26): kernel-headers-3.10.0-1160.119.1.el7.x86_64.rpm | 9.1 MB 00:00:09
(19/26): gcc-4.8.5-44.el7.x86_64.rpm | 16 MB 00:00:15
(20/26): openssl-devel-1.0.2k-26.el7_9.x86_64.rpm | 1.5 MB 00:00:01
(21/26): zlib-1.2.7-21.el7_9.x86_64.rpm | 90 kB 00:00:00
(22/26): pcre-devel-8.32-17.el7.x86_64.rpm | 480 kB 00:00:00
(23/26): zlib-devel-1.2.7-21.el7_9.x86_64.rpm | 50 kB 00:00:00
(24/26): openssl-libs-1.0.2k-26.el7_9.x86_64.rpm | 1.2 MB 00:00:01
(25/26): golang-src-1.20.12-1.el7.noarch.rpm | 12 MB 00:00:11
(26/26): golang-bin-1.20.12-1.el7.x86_64.rpm | 65 MB 00:00:43
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Total 2.7 MB/s | 131 MB 00:00:48
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Updating : glibc-2.17-326.el7_9.3.x86_64 1/32
Updating : glibc-common-2.17-326.el7_9.3.x86_64 2/32
Updating : zlib-1.2.7-21.el7_9.x86_64 3/32
Updating : krb5-libs-1.15.1-55.el7_9.x86_64 4/32
Updating : 1:openssl-libs-1.0.2k-26.el7_9.x86_64 5/32
Installing : mpfr-3.1.1-4.el7.x86_64 6/32
Installing : libmpc-1.0.1-3.el7.x86_64 7/32
Installing : cpp-4.8.5-44.el7.x86_64 8/32
Installing : libkadm5-1.15.1-55.el7_9.x86_64 9/32
Installing : zlib-devel-1.2.7-21.el7_9.x86_64 10/32
Installing : libcom_err-devel-1.42.9-19.el7.x86_64 11/32
Installing : kernel-headers-3.10.0-1160.119.1.el7.x86_64 12/32
Installing : glibc-headers-2.17-326.el7_9.3.x86_64 13/32
Installing : glibc-devel-2.17-326.el7_9.3.x86_64 14/32
Installing : gcc-4.8.5-44.el7.x86_64 15/32
Installing : libverto-devel-0.2.5-4.el7.x86_64 16/32
Installing : libsepol-devel-2.5-10.el7.x86_64 17/32
Installing : golang-src-1.20.12-1.el7.noarch 18/32
Installing : pcre-devel-8.32-17.el7.x86_64 19/32
Installing : libselinux-devel-2.5-15.el7.x86_64 20/32
Installing : keyutils-libs-devel-1.5.8-3.el7.x86_64 21/32
Installing : krb5-devel-1.15.1-55.el7_9.x86_64 22/32
Installing : 1:openssl-devel-1.0.2k-26.el7_9.x86_64 23/32
Installing : golang-bin-1.20.12-1.el7.x86_64 24/32
Installing : golang-1.20.12-1.el7.x86_64 25/32
Updating : 1:openssl-1.0.2k-26.el7_9.x86_64 26/32
Cleanup : 1:openssl-1.0.2k-19.el7.x86_64 27/32
Cleanup : krb5-libs-1.15.1-50.el7.x86_64 28/32
Cleanup : 1:openssl-libs-1.0.2k-19.el7.x86_64 29/32
Cleanup : zlib-1.2.7-18.el7.x86_64 30/32
Cleanup : glibc-common-2.17-317.el7.x86_64 31/32
Cleanup : glibc-2.17-317.el7.x86_64 32/32
Verifying : libselinux-devel-2.5-15.el7.x86_64 1/32
Verifying : keyutils-libs-devel-1.5.8-3.el7.x86_64 2/32
Verifying : glibc-headers-2.17-326.el7_9.3.x86_64 3/32
Verifying : krb5-devel-1.15.1-55.el7_9.x86_64 4/32
Verifying : pcre-devel-8.32-17.el7.x86_64 5/32
Verifying : zlib-1.2.7-21.el7_9.x86_64 6/32
Verifying : golang-src-1.20.12-1.el7.noarch 7/32
Verifying : 1:openssl-devel-1.0.2k-26.el7_9.x86_64 8/32
Verifying : libsepol-devel-2.5-10.el7.x86_64 9/32
Verifying : libverto-devel-0.2.5-4.el7.x86_64 10/32
Verifying : 1:openssl-libs-1.0.2k-26.el7_9.x86_64 11/32
Verifying : cpp-4.8.5-44.el7.x86_64 12/32
Verifying : golang-bin-1.20.12-1.el7.x86_64 13/32
Verifying : zlib-devel-1.2.7-21.el7_9.x86_64 14/32
Verifying : 1:openssl-1.0.2k-26.el7_9.x86_64 15/32
Verifying : glibc-common-2.17-326.el7_9.3.x86_64 16/32
Verifying : krb5-libs-1.15.1-55.el7_9.x86_64 17/32
Verifying : glibc-2.17-326.el7_9.3.x86_64 18/32
Verifying : gcc-4.8.5-44.el7.x86_64 19/32
Verifying : libmpc-1.0.1-3.el7.x86_64 20/32
Verifying : golang-1.20.12-1.el7.x86_64 21/32
Verifying : libkadm5-1.15.1-55.el7_9.x86_64 22/32
Verifying : glibc-devel-2.17-326.el7_9.3.x86_64 23/32
Verifying : mpfr-3.1.1-4.el7.x86_64 24/32
Verifying : kernel-headers-3.10.0-1160.119.1.el7.x86_64 25/32
Verifying : libcom_err-devel-1.42.9-19.el7.x86_64 26/32
Verifying : glibc-common-2.17-317.el7.x86_64 27/32
Verifying : zlib-1.2.7-18.el7.x86_64 28/32
Verifying : 1:openssl-1.0.2k-19.el7.x86_64 29/32
Verifying : 1:openssl-libs-1.0.2k-19.el7.x86_64 30/32
Verifying : glibc-2.17-317.el7.x86_64 31/32
Verifying : krb5-libs-1.15.1-50.el7.x86_64 32/32
Installed:
golang.x86_64 0:1.20.12-1.el7
Dependency Installed:
cpp.x86_64 0:4.8.5-44.el7 gcc.x86_64 0:4.8.5-44.el7 glibc-devel.x86_64 0:2.17-326.el7_9.3 glibc-headers.x86_64 0:2.17-326.el7_9.3 golang-bin.x86_64 0:1.20.12-1.el7 golang-src.noarch 0:1.20.12-1.el7
kernel-headers.x86_64 0:3.10.0-1160.119.1.el7 keyutils-libs-devel.x86_64 0:1.5.8-3.el7 krb5-devel.x86_64 0:1.15.1-55.el7_9 libcom_err-devel.x86_64 0:1.42.9-19.el7 libkadm5.x86_64 0:1.15.1-55.el7_9 libmpc.x86_64 0:1.0.1-3.el7
libselinux-devel.x86_64 0:2.5-15.el7 libsepol-devel.x86_64 0:2.5-10.el7 libverto-devel.x86_64 0:0.2.5-4.el7 mpfr.x86_64 0:3.1.1-4.el7 openssl-devel.x86_64 1:1.0.2k-26.el7_9 pcre-devel.x86_64 0:8.32-17.el7
zlib-devel.x86_64 0:1.2.7-21.el7_9
Dependency Updated:
glibc.x86_64 0:2.17-326.el7_9.3 glibc-common.x86_64 0:2.17-326.el7_9.3 krb5-libs.x86_64 0:1.15.1-55.el7_9 openssl.x86_64 1:1.0.2k-26.el7_9 openssl-libs.x86_64 1:1.0.2k-26.el7_9 zlib.x86_64 0:1.2.7-21.el7_9
Complete!
[root@hellogitlab ~]#2.2 查看Golang版本
sh
[root@hellogitlab ~]# go version
go version go1.20.12 linux/amd642.3 查看go命令的帮助信息
sh
[root@hellogitlab ~]# go
Go is a tool for managing Go source code.
Usage:
go <command> [arguments]
The commands are:
bug start a bug report
build compile packages and dependencies
clean remove object files and cached files
doc show documentation for package or symbol
env print Go environment information
fix update packages to use new APIs
fmt gofmt (reformat) package sources
generate generate Go files by processing source
get add dependencies to current module and install them
install compile and install packages and dependencies
list list packages or modules
mod module maintenance
work workspace maintenance
run compile and run Go program
test test packages
tool run specified go tool
version print Go version
vet report likely mistakes in packages
Use "go help <command>" for more information about a command.
Additional help topics:
buildconstraint build constraints
buildmode build modes
c calling between Go and C
cache build and test caching
environment environment variables
filetype file types
go.mod the go.mod file
gopath GOPATH environment variable
gopath-get legacy GOPATH go get
goproxy module proxy protocol
importpath import path syntax
modules modules, module versions, and more
module-get module-aware go get
module-auth module authentication using go.sum
packages package lists and patterns
private configuration for downloading non-public code
testflag testing flags
testfunc testing functions
vcs controlling version control with GOVCS
Use "go help <topic>" for more information about that topic.
[root@hellogitlab ~]#2.4 go安装信息检查
sh
# 查看go处于什么位置
[root@hellogitlab ~]# whereis go
go: /usr/bin/go
# 查看/usr/bin/go的详细信息，可以看到最终指向了/usr/lib/golang/bin/go
[root@hellogitlab ~]# ls -lah /usr/bin/go
lrwxrwxrwx. 1 root root 22 Nov 7 21:16 /usr/bin/go -> /usr/lib/golang/bin/go
[root@hellogitlab ~]# ls -lah /usr/lib/golang/bin/go
-rwxr-xr-x. 1 root root 16M Mar 6 2024 /usr/lib/golang/bin/go
# golang的安装目录
[root@hellogitlab ~]# ls -lah /usr/lib/golang/
total 16K
drwxr-xr-x. 7 root root 76 Nov 7 21:16 .
dr-xr-xr-x. 29 root root 4.0K Nov 7 21:16 ..
drwxr-xr-x. 2 root root 4.0K Nov 7 21:16 api
drwxr-xr-x. 2 root root 29 Nov 7 21:16 bin
drwxr-xr-x. 3 root root 18 Nov 7 21:16 lib
drwxr-xr-x. 4 root root 33 Nov 7 21:16 pkg
drwxr-xr-x. 48 root root 4.0K Nov 7 21:16 src
-rw-r--r--. 1 root root 9 Dec 6 2023 VERSION
[root@hellogitlab ~]#我们后续使用普通账户meizhaohui来进行go语言相关命令的操作。
2.5 配置Go的工作空间
GO代码必须在工作空间内。工作空间是一个目录，其中包含三个子目录：
src里面每一个子目录，就是一个包。包内是Go的源码文件pkg编译后生成的，包的目标文件bin生成的可执行文件
使用普通账户meizhaohui创建Go的工作空间目录：
sh
# 查看我是谁
[meizhaohui@hellogitlab ~]$ whoami
meizhaohui
# 查看当前文件夹中的文件
[meizhaohui@hellogitlab ~]$ ls
# 创建工作空间目录
[meizhaohui@hellogitlab ~]$ mkdir -p data/go_data
[meizhaohui@hellogitlab ~]$ ls -lsh data/
total 0
0 drwxrwxr-x. 5 meizhaohui meizhaohui 39 Nov 7 21:37 go_data
# 在工作空间目录下面创建子目录
[meizhaohui@hellogitlab ~]$ mkdir -p data/go_data/{src,bin,pkg}
[meizhaohui@hellogitlab ~]$ ls -lah data/go_data/
total 0
drwxrwxr-x. 5 meizhaohui meizhaohui 39 Nov 7 21:37 .
drwxrwxr-x. 3 meizhaohui meizhaohui 21 Nov 7 21:37 ..
drwxrwxr-x. 2 meizhaohui meizhaohui 6 Nov 7 21:37 bin
drwxrwxr-x. 2 meizhaohui meizhaohui 6 Nov 7 21:37 pkg
drwxrwxr-x. 2 meizhaohui meizhaohui 6 Nov 7 21:37 src
[meizhaohui@hellogitlab ~]$2.6 配置PATH、GOPATH、GOROOT、GOBIN等环境变量
在~/.bashrc文件中增加以下内容：
# Golang environment settings
export GOROOT=/usr/lib/golang # golang install path
export GOPATH=/home/meizhaohui/data/go_data # golang workspace
export GOBIN=${GOPATH}/bin # golang exe files
export PATH=${GOBIN}:${PATH}保存后，source ~/.bashrc加载配置文件，并查看以上设置的Go语言的环境变量：
sh
[meizhaohui@hellogitlab ~]$ source ~/.bashrc
[meizhaohui@hellogitlab ~]$ echo $GOPATH
/home/meizhaohui/data/go_data
[meizhaohui@hellogitlab ~]$ echo $GOBIN
/home/meizhaohui/data/go_data/bin
[meizhaohui@hellogitlab ~]$ echo $GOROOT
/usr/lib/golang
[meizhaohui@hellogitlab ~]$ echo $PATH
/home/meizhaohui/data/go_data/bin:/usr/local/bin:/usr/bin:/usr/local/sbin:/usr/sbin:/home/meizhaohui/.local/bin:/home/meizhaohui/bin查看到以上信息，说环境变量配置成功。
2.7 开启Go module和代理
默认情况下，使用go get下载包时会非常慢，需要开启Go module和代理，加快我们包的安装速度。
为了今后中国的Go语言开发者能更好地进行开发，七牛云推出了非营利性项目 goproxy.cn，其目标是为中国和世界上其他地方的 Gopher 们提供一个免费的、可靠的、持续在线的且经过 CDN 加速的模块代理。
参考：
- 干货满满的 Go Modules 和 goproxy.cn https://github.com/EDDYCJY/blog/blob/master/talk/goproxy-cn.md
- Go module和goproxy 设置https://luhua.cc/2019/08/23/Go-module-%E5%92%8C-goproxy-%E8%AE%BE%E7%BD%AE/
在~/.bashrc文件中增加以下内容：
sh
export GO111MODULE=on
export GOPROXY=https://goproxy.cn保存后，source ~/.bashrc加载配置文件，并查看以上设置的Go语言的环境变量：
sh
[meizhaohui@hellogitlab ~]$ echo $GO111MODULE
on
[meizhaohui@hellogitlab ~]$ echo $GOPROXY
https://goproxy.cn
# 测试安装包
# go get 跟go.mod 紧密相关，它需要go.mod ，并且每次更改都会记录在go.mod中，当你在一个没有go.mod的路径下（指的是此路径，此路径的父路径也没有）使用go get 会提示如下错误
[meizhaohui@hellogitlab ~]$ go get -v github.com/stamblerre/gocode
go: go.mod file not found in current directory or any parent directory.
'go get' is no longer supported outside a module.
To build and install a command, use 'go install' with a version,
like 'go install example.com/cmd@latest'
For more information, see https://golang.org/doc/go-get-install-deprecation
or run 'go help get' or 'go help install'.
[meizhaohui@hellogitlab ~]$此时，使用go install代替下载包：
sh
# go install 用于下载包，两者都是一样的，如果包的后面带上版本那么就是指定版本
[meizhaohui@hellogitlab ~]$ go install github.com/stamblerre/gocode
go: 'go install' requires a version when current directory is not in a module
Try 'go install github.com/stamblerre/gocode@latest' to install the latest version
[meizhaohui@hellogitlab ~]$ echo $?
1
[meizhaohui@hellogitlab ~]$ go install github.com/stamblerre/gocode@latest
go: downloading github.com/stamblerre/gocode v1.0.0
go: downloading github.com/keegancsmith/rpc v1.1.0
go: downloading golang.org/x/tools v0.0.0-20191030062658-86caa796c7ab
[meizhaohui@hellogitlab ~]$ echo $?
0
[meizhaohui@hellogitlab ~]$在使用 go install的时候其实是忽略 go.mod 的，所以go install 跟go.mod 没有任何关系，也不会记录go.mod中，它的作用就是下载包。
3. 第一个Go程序，你好世界
3.1 编写Go代码文件
以最经典的Hello world程序为例，编写第一个Go代码文件。
我们切换到$GOPATH/src目录中，创建第一个Go代码文件。
sh
[meizhaohui@hellogitlab ~]$ cd $GOPATH/src
[meizhaohui@hellogitlab src]$ pwd
/home/meizhaohui/data/go_data/src
# 使用vim编写hello.go文件，保存后查看内容如下
[meizhaohui@hellogitlab src]$ cat hello.go
package main
import "fmt"
func main() {
fmt.Println("Hello,World")
}由于后期经常会切换到$GOPATH/src这个目录来编写代码，我们可以在~/.bashrc中设置一个快捷命令：
sh
alias cdgo='cd ${GOPATH}/src && pwd'修改后使用source ~/.bashrc使快捷命令生效。
查看效果：
sh
[meizhaohui@hellogitlab ~]$ cdgo
/home/meizhaohui/data/go_data/src3.2 编译Go程序go build
- 使用
go build filename.go编译go程序，如go build hello.go编译生成可执行文件hello。
sh
[meizhaohui@hellogitlab src]$ go build hello.go
[meizhaohui@hellogitlab src]$ ls
hello hello.go
# 运行可执行文件hello
[meizhaohui@hellogitlab src]$ ./hello
Hello,World3.3 编译并直接运行Go程序go run
- 使用
go run filename.go编译并直接运行go程序，如go build hello.go编译时不生成可执行文件，直接显示运行结果。
sh
[meizhaohui@hellogitlab src]$ rm -f hello
[meizhaohui@hellogitlab src]$ ls
hello.go
[meizhaohui@hellogitlab src]$ go run hello.go
Hello,World
[meizhaohui@hellogitlab src]$ ls
hello.go3.4 编译并安装go install
- 对go源码文件
go install,会进行编译+链接+生成可执行文件, 会在$GOBIN目录下生成可执行文件。
sh
# 编译并安装
[meizhaohui@hellogitlab src]$ go install hello.go
# 查看当前目录下是否生成可执行文件
[meizhaohui@hellogitlab src]$ ls
hello.go
# 查看bin目录下是否生成可执行文件
[meizhaohui@hellogitlab src]$ ls $GOBIN
hello
# 查看hello可执行文件的位置
[meizhaohui@hellogitlab src]$ whereis hello
hello: /home/meizhaohui/data/go_data/bin/hello
# 在任何目录执行hello，会打印出世界你好
[meizhaohui@hellogitlab src]$ hello
Hello,World
[meizhaohui@hellogitlab src]$ cd
[meizhaohui@hellogitlab ~]$ hello
Hello,Worldgolang的安装和简单使用就到此了。