xxd -i but for go

package xxdgo

import (
    "fmt"
    "io"
    "os"
    "regexp"
    "strings"

    "github.com/spf13/cobra"
)

var (
    space string
    lineBreak int
)

func init() {
    Cmd.Flags().StringVarP(&space, "spaces", "s", "   ", "how much space to use after every break line")
    Cmd.Flags().IntVarP(&lineBreak, "break", "b", 12, "after how many items to add a new break line")
}

func initVarName(v string) string {
    var allowed = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890"

    var s = strings.Split(v, "")

    for i, c := range s {
        if !strings.Contains(allowed, string(c)) {
            s[i] = "_"
        }
    }

    v = strings.Join(s, "")
    v = regexp.MustCompile(`^_`).ReplaceAllString(v, "I")
    v = regexp.MustCompile(`^\d`).ReplaceAllString(v, "I")
    v = strings.ToUpper(string(v[0])) + v[1:]

    return v
}

var Cmd = &cobra.Command{
    Long: "xxd -i but for go",

    Use: "xxdgo file_name",

    Example: `xxdgo image.png -s "  " -b 16 >> bytes.go`,

    Args: cobra.ExactArgs(1),

    RunE: func(cmd *cobra.Command, args []string) error {
        file, err := os.OpenFile(args[0], os.O_RDONLY, 0444)

        if err != nil {
            return err
        }

        defer file.Close()

        fileBytes, err := io.ReadAll(file)

        if err != nil {
            return err
        }

        var s strings.Builder

        s.WriteString("\n")
        s.WriteString(`var `)

        var varName = initVarName(file.Name())

        s.WriteString(varName)
        s.WriteString(` []byte = []byte{`)
        s.WriteString("\n")
        s.WriteString(space)

        for i, b := range fileBytes {
            s.WriteString(`0x`)

            var hexB = fmt.Sprintf("%x", b)

            if len(hexB) == 1 {
                s.WriteString("0")
            }

            s.WriteString(hexB)
            s.WriteString(", ")

            if (i + 1) % lineBreak == 0 {
                s.WriteString("\n")
                s.WriteString(space)
            }
        }

        s.WriteString("\n")
        s.WriteString("}")

        fmt.Println(s.String())

        return nil
    },
}