--- /dev/null
+# 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
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