How to create nested directories using Mkdir in Golang

Question

I am trying to create a set of nested directories from a Go executable such as  dir1 dir2 dir3   I have succeeded in creating a single directory with this line   os Mkdir       string filepath Separator    c Args   First   0777     However  I have no idea how to approach creating a predetermined nested set of directories inside of that directory

User · Answer

An utility method like the following can be used to solve this   import      os     path filepath     log     func ensureDir fileName string      dirName    filepath Dir fileName    if    serr    os Stat dirName   serr    nil       merr    os MkdirAll dirName  os ModePerm      if merr    nil           panic merr                 func main          cerr    os Create  a b c d txt     if cerr    nil       log Fatal  error creating a b c   cerr        log Println  created file in a sub-directory

User · Answer

os Mkdir is used to create a single directory  To create a folder path  instead try using   os MkdirAll folderPath  os ModePerm    Go documentation     func MkdirAll path string  perm FileMode  error        MkdirAll creates a directory named path  along with any necessary parents  and returns nil  or else returns an error  The permission bits perm are used for all directories that MkdirAll creates  If path is already a directory  MkdirAll does nothing and returns nil    Edit   Updated to correctly use os ModePerm instead  For concatenation of file paths  use package path filepath as described in  Chris  answer

User · Answer

This is one alternative for achieving the same but it avoids race condition caused by having two distinct  check   and   create  operations   package main  import        fmt       os     func main          if err    ensureDir   test-dir    err    nil           fmt Println  Directory creation failed with error      err Error            os Exit 1               Proceed forward    func ensureDir dirName string  error        err    os MkdirAll dirName  os ModeDir       if err    nil    os IsExist err            return nil       else           return err

User · Answer

If the issue is to create all the necessary parent directories  you could consider using os MkDirAll       MkdirAll creates a directory named path  along with any necessary parents  and returns nil  or else returns an error    The path test go is a good illustration on how to use it   func TestMkdirAll t  testing T        tmpDir    TempDir       path    tmpDir      TestMkdirAll  dir   dir2      err    MkdirAll path  0777      if err    nil       t Fatalf  MkdirAll  q   s   path  err            defer RemoveAll tmpDir      TestMkdirAll             Make sure to specify a sensible permission value  as mentioned in this answer

User · Answer

This way you don t have to use any magic numbers   os MkdirAll newPath  os ModePerm    Also  rather than using   to create paths  you can use   import  path filepath  path    filepath Join someRootPath  someSubPath    The above uses the correct separators automatically on each platform for you

[go] How to create nested directories using Mkdir in Golang?

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