我们写习惯了C代码,都知道了解析输入参数argc argv,获取环境变量env,常见的C语言main函数有:
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int main(int argc,char* argv[],char** envp)
我们首先给出C语言的获取命令行参数和环境变量的代码:
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manu@manu-hacks:~/code/c/self/env$ cat env.c
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#include<stdio.h>
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#include<stdlib.h>
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int main(int argc,char* argv[],char** envp)
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{
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int i;
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printf("there are %d input param\n",argc);
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printf("they are :\n");
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for(i = 0 ; i < argc ; i++)
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{
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printf("%s\n",argv[i]);
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}
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printf("env LIST--------------------------------------\n");
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char **p = envp;
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for(;*p != NULL;p++)
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{
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printf("%s\n",*p);
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}
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return 0;
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}
golang自然也可以做到,获取命令行参数,获取环境变量。
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manu@manu-hacks:~/code/go/self$ godoc os Args
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PACKAGE DOCUMENTATION
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package os
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import "os"
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VARIABLES
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var Args []string
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Args hold the command-line arguments, starting with the program name.
我们先写一个简单的获取命令行参数的go 程序:
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manu@manu-hacks:~/code/go/self$ cat sum.go
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package main
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import "fmt"
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import "os"
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import "strconv"
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func main() int{
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arg_num := len(os.Args)
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fmt.Printf("the num of input is %d\n",arg_num)
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fmt.Printf("they are :\n")
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for i := 0 ; i < arg_num ;i++{
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fmt.Println(os.Args[i])
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}
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sum := 0
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for i := 1 ; i < arg_num; i++{
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curr,err := strconv.Atoi(os.Args[i])
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if(err != nil){
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fmt.Println("error happened ,exit")
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return 1
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}
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sum += curr
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}
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fmt.Printf("sum of Args is %d\n",sum)
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return 0
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}
输出如下:
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manu@manu-hacks:~/code/go/self$ ./sum 1 2 4
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the num of input is 4
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they are :
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./sum
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1
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2
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4
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sum of Args is 7
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manu@manu-hacks:~/code/go/self$ ./sum 1 2 4 f 5
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the num of input is 6
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they are :
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./sum
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1
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2
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4
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f
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5
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error happened ,exit
另外一个方面是如何获取环境变量。对于C而言,直接就是 之际而言os中也有获取环境变量的函数:
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FUNCTIONS
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func Environ() []string
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Environ returns a copy of strings representing the environment, in the
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form "key=value".
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func Getenv(key string) string
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Getenv retrieves the value of the environment variable named by the key.
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It returns the value, which will be empty if the variable is not
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present.
有了这个,就简单了。写了个简单的例子:
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manu@manu-hacks:~/code/go/self$ cat env.go
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package main
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import "fmt"
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import "os"
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func main(){
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environ := os.Environ()
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for i := range environ {
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fmt.Println(environ[i])
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}
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fmt.Println("------------------------------------------------------------\n")
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logname := os.Getenv("LOGNAME")
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fmt.Printf("logname is %s\n",logname)
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}
输出如下:
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manu@manu-hacks:~/code/go/self$ go run env.go
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SSH_AGENT_PID=2331
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GPG_AGENT_INFO=/tmp/keyring-5CkALe/gpg:0:1
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TERM=xterm
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SHELL=/bin/bash
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。。。
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------------------------------------------------------------
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logname is manu
参考文献
1 Package os
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