[go-nuts] Creating a file in a directory

wrote:
I'm trying to take a filepath string and create a Method on a type that stores it to parse the string, create the relevant directories if needed and create the file. I seem to be able to create the directory as I might expect but I get an error when trying to create the file. How do you create a file in a directory in Go? I'm very new to all of this and the NewFile fd property seems like it might be what I need but the uintptr is escaping me right now.


I'm pasting the method I'm having trouble with below. Thank you for any insight.



// Writes key value pairs to a tag file.

func (tf *TagFile) Create() {

// Create directory if needed.

basepath := path.Dir(tf.Filepath)

filename := path.Base(tf.Filepath)

if os.MkdirAll(basepath, 0666) != nil {

you should change 0666 to 0777. or you won't be able to create
files in a dir with perm 0666.
panic("Unable to create directory for tagfile!")

}


// Create the tagfile.

fileOut, err := os.Create(strings.Join([]string{basepath, filename}, "/"))

you'd better use path/filepath.Join for this.
if err != nil {

panic("Unable to create tag file!")

}

defer fileOut.Close()


// Write fields and data to the file.

for key, data := range tf.Data {

_, err := io.WriteString(fileOut, fmt.Sprintln(formatField(key, data)))

why not use fmt.Fprintln directly?
if err != nil {

panic("Unable to write data to tagfile.")

}

}

}

wrote:
I'm trying to take a filepath string and create a Method on a type that stores it to parse the string, create the relevant directories if needed and create the file. I seem to be able to create the directory as I might expect but I get an error when trying to create the file. How do you create a file in a directory in Go? I'm very new to all of this and the NewFile fd property seems like it might be what I need but the uintptr is escaping me right now.


I'm pasting the method I'm having trouble with below. Thank you for any insight.



// Writes key value pairs to a tag file.

func (tf *TagFile) Create() {

// Create directory if needed.

basepath := path.Dir(tf.Filepath)

filename := path.Base(tf.Filepath)

if os.MkdirAll(basepath, 0666) != nil {

you should change 0666 to 0777. or you won't be able to create
files in a dir with perm 0666.
panic("Unable to create directory for tagfile!")

}


// Create the tagfile.

fileOut, err := os.Create(strings.Join([]string{basepath, filename}, "/"))

you'd better use path/filepath.Join for this.
if err != nil {

panic("Unable to create tag file!")

}

defer fileOut.Close()


// Write fields and data to the file.

for key, data := range tf.Data {

_, err := io.WriteString(fileOut, fmt.Sprintln(formatField(key, data)))

why not use fmt.Fprintln directly?
if err != nil {

panic("Unable to write data to tagfile.")

}

}

}

On Thu, May 30, 2013 at 4:14 AM, Scott Turnbull wrote:

Alright I think I have this fixed but I'm not sure I understand it.
using 0777 directly for the FileMode does not result in the permission I
would expect. using os.ModePerm does however and using that I can write
the file just fine.

On Thu, May 30, 2013 at 4:14 AM, Scott Turnbull <stream...@gmail.com<javascript:>
the actual permission is still subject to your umask setting.

what do you mean by "using os.ModePerm does"?
could you please show what changes made the program working correctly?

using 0777 for os.MkdirAll normally should work just ok (except when
you're
concerned about others reading your directories, but at least you need rwx
perm. for the owner if you want to use the directory normally).