英文:
In golang os.OpenFile doesn't return os.ErrNotExist if file does not exist
问题
我正在尝试打开一个文件，并且我想知道如果文件不存在时应该如何处理。但是，当文件不存在时，使用以下代码：
os.OpenFile(fName, os.O_WRONLY, 0600)
返回的错误与os.ErrNotExists不同：
os.ErrNotExists -> "文件不存在"
err.(*os.PathError).Err -> "没有这样的文件或目录"
如果文件不存在，os.Stat也会返回相同的错误。是否有预定义的错误可以进行比较，而不是手动处理呢？
英文:
I'm trying to open a file and I'd like to know if it doesn't exist to react. But the error
os.OpenFile(fName, os.O_WRONLY, 0600)
returns when the file does not exist is different than os.ErrNotExists
os.ErrNotExists -> "file does not exist"
err.(*os.PathError).Err -> "no such file or directory"
os.Stat also return the same error if the file is not there. Is there a predefined error I can compare to instead of having to do it by hand?
答案1
得分: 23
> 包 os
>
> func IsExist
>
> func IsExist(err error) bool
>
> IsExist 函数返回一个布尔值，指示错误是否已知为文件或目录已存在的报告。它适用于 ErrExist 和一些系统调用错误。
>
> func IsNotExist
>
> func IsNotExist(err error) bool
>
> IsNotExist 函数返回一个布尔值，指示错误是否已知为文件或目录不存在的报告。它适用于 ErrNotExist 和一些系统调用错误。
使用 os.IsNotExist 函数。例如：
package main
import (
"fmt"
"os"
)
func main() {
fname := "No File"
_, err := os.OpenFile(fname, os.O_WRONLY, 0600)
if err != nil {
if os.IsNotExist(err) {
fmt.Print("文件不存在：")
}
fmt.Println(err)
}
}
输出：
文件不存在：open No File: 没有该文件或目录
英文:
> Package os
>
> func IsExist
>
> func IsExist(err error) bool
>
> IsExist returns a boolean indicating whether the error is known to
> report that a file or directory already exists. It is satisfied by
> ErrExist as well as some syscall errors.
>
> func IsNotExist
>
> func IsNotExist(err error) bool
>
> IsNotExist returns a boolean indicating whether the error is known to
> report that a file or directory does not exist. It is satisfied by
> ErrNotExist as well as some syscall errors.
Use the os.IsNotExist function. For example,
package main
import (
"fmt"
"os"
)
func main() {
fname := "No File"
_, err := os.OpenFile(fname, os.O_WRONLY, 0600)
if err != nil {
if os.IsNotExist(err) {
fmt.Print("File Does Not Exist: ")
}
fmt.Println(err)
}
}
Output:
File Does Not Exist: open No File: No such file or directory
答案2
得分: 2
根据Go 1.17的最新规定，检查这个错误的首选方法是：
errors.Is(err, fs.ErrNotExist)
英文:
Originally posted as an anonymous suggested edit to the other answer:
As of Go 1.17, the preferred way to check for this error is:
errors.Is(err, fs.ErrNotExist)
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