Golang os.Create path with nested directories

Question

As mentioned in GoDocs, os.Create() creates a file in specific path.

os.Create("fonts/foo/font.eot")

But when fonts or foo doesn't exists, it returns panic: open fonts/foo/font.eot: The system cannot find the path specified.
So i used os.MkdirAll() to create nested directory. But there are many other problems with this function.

path := "fonts/foo/font.eot"
// this line create a directory named (font.eot) !
os.MkdirAll(path, os.ModePerm)

Is there any better way to create a file in nested directories?

That's the proper way to do such things - on the system level those map to mkdir and open system calls. What "many other problems" are you referring to? — oakad
– oakad, Commented Jan 29, 2020 at 6:26
It is os.MkdirAll("fonts/foo", 0770); os.Create("fonts/foo/font.eot") Dead simple and totaly obvious. — Volker
– Volker, Commented Jan 29, 2020 at 6:29
@Volker: most programs should probably use mode 0777 rather than 0770 here. File creation generally should use mode 0666. These allow the user's umask to take away group and/or other write permissions if desired, or even more permissions (resulting in modes like 0750 or 0700 for a directory) if desired. (I've seen this advice to use 0770 elsewhere, but am not sure where it originates.) — torek
– torek, Commented Jan 29, 2020 at 8:17
@torek Neither the filepaths nor the modes are fixed and need adoption to your particular use case. There is no single correct value. — Volker
– Volker, Commented Jan 29, 2020 at 10:29

stantonJones · Accepted Answer · 2020-01-29 06:34:46Z

32

The standard way is something like this:

func create(p string) (*os.File, error) {
    if err := os.MkdirAll(filepath.Dir(p), 0770); err != nil {
        return nil, err
    }
    return os.Create(p)
}

A few notes:

os.Create does not panic as stated in the question.
Create a directory from the directory part of the file path, not the full path.

answered Jan 29, 2020 at 6:34

stantonJones

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atultw Over a year ago

Second note is important!

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