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© 2019 Zephyr

基于 Go 开发 CLI 命令行程序

發佈於 2018-10-03 Go  go /

使用 go 开发 selpg 命令

前期准备

  1. 安装 pflag
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$ go get github.com/spf13/pflag
  1. 测试是否安装成功
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$ $ go test github.com/spf13/pflag

编码开始

  1. 引入相关包
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import (
	"bufio"
	"fmt"
	"io"
	"os"
	"os/exec"

	flag "github.com/spf13/pflag"
)
  1. 定义数据结构
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type Selpg struct {
	startPage, endPage, pageLines, totalPages int
	destination, inputFile string
	fromFeed bool
}
  1. 判断文件是否为空
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if sp.inputFile != "" {
	file, err := os.Open(sp.inputFile)
	if err != nil {
		fmt.Printf("%v: error: %v, %v\n", os.Args[0], sp.inputFile, err)
		os.Exit(1)
	}
	reader = file
} 
else {
	reader = os.Stdin
}
bufReader := bufio.NewReader(reader)
bufWriter := bufio.NewWriter(writer)
  1. 文件分页
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currentPage := 1
	for runningFlag := true; runningFlag ;{
		ch, err := bufReader.ReadByte()
		if err != nil {
			if err == io.EOF {
				runningFlag = false
			} 
			else {
				log.Fatalf("Error: %v\n", err)
				os.Exit(1)
			}
		}
		if currentPage >= sp.startPage && currentPage <= sp.endPage {
			bufWriter.WriteByte(ch)
		}
		if ch == '\f' {
			bufWriter.Flush()
			currentPage += 1
		}
	}
	totalPages = currentPage

测试

Case 1

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# test1.sh

for ((i=1;i<20;i++))
do
    echo "line" $i >> test
done

Input

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$ selpg --s 1 --e 1 test1

Output

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line 1
line 2
line 3
line 4
line 5
line 6
line 7
line 8
line 9
line 10
line 11
line 12
line 13
line 14
line 15
line 16
line 17
line 18
line 19

Case 2

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# test2.sh

for ((i=1;i<20;i += 4))
do
    echo "line" $i >> testpage
    echo "line" $i+1 >> testpage
    echo "line" $i+2 >> testpage
    echo "line" $i+3 >> testpage
    echo -e '\f' >> testpage
done

Input

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$ selpg --s 1 --e 3 test2

Output

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line 1
line 1+1
line 1+2
line 1+3

line 5
line 5+1
line 5+2
line 5+3

line 9
line 9+1
line 9+2
line 9+3

line 13
line 13+1
line 13+2
line 13+3

line 17
line 17+1
line 17+2
line 17+3

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© 2019 Zephyr