# umask
Convert umask from string <-> number.
## Installation & Use
```
$ npm install -S umask
var umask = require('umask');
console.log(umask.toString(18)); // 0022
console.log(umask.fromString('0777')) // 511
```
## API
### `toString( val )`
Converts `val` to a 0-padded octal string. `val` is assumed to be a
Number in the correct range (0..511)
### `fromString( val, [cb] )`
Converts `val` to a Number that can be used as a umask. `val` can
be of the following forms:
* String containing octal number (leading 0)
* String containing decimal number
* Number
In all cases above, the value obtained is then converted to an integer and
checked against the legal `umask` range 0..511
`fromString` can be used as a simple converter, with no error feedback, by
omitting the optional callback argument `cb`:
```
var mask = umask.fromString(val);
// mask is now the umask descibed by val or
// the default, 0022 (18 dec)
```
The callback arguments are `(err, val)` where `err` is either `null` or an
Error object and `val` is either the converted umask or the default umask, `0022`.
```
umask.fromString(val, function (err, val) {
if (err) {
console.error("invalid umask: " + err.message)
}
/* do something with val */
});
```
The callback, if provided, is always called **synchronously**.
### `validate( data, k, val )`
This is a validation function of the form expected by `nopt`. If
`val` is a valid umask, the function returns true and sets `data[k]`.
If `val` is not a valid umask, the function returns false.
The `validate` function is stricter than `fromString`: it only accepts
Number or octal String values, and the String value must begin with `0`.
The `validate` function does **not** accept Strings containing decimal
numbers.
# Maintainer
Sam Mikes <smikes@cubane.com>
# License
MIT