    var rollers = require('streamroller');
    var stream = new rollers.RollingFileStream('myfile', 1024, 3);
    stream.write("stuff");
    stream.end();

The streams behave the same as standard node.js streams, except that when certain conditions are met they will rename the current file to a backup and start writing to a new file.

new RollingFileStream(filename [, maxSize, numBackups, options])

filename (String)
maxSize - the size in bytes to trigger a rollover, if not provided this defaults to MAX_SAFE_INTEGER and the stream will not roll.
numBackups - the number of old files to keep
options - Object
- encoding - defaults to 'utf8'
- mode - defaults to 0644
- flags - defaults to 'a'
- compress - (boolean) defaults to false - compress the backup files using gzip (files will have .gz extension).

This returns a WritableStream. When the current file being written to (given by filename) gets up to or larger than maxSize, then the current file will be renamed to filename.1 and a new file will start being written to. Up to numBackups of old files are maintained, so if numBackups is 3 then there will be 4 files:

     filename
     filename.1
     filename.2
     filename.3

When filename size >= maxSize then:

     filename -> filename.1
     filename.1 -> filename.2
     filename.2 -> filename.3
     filename.3 gets overwritten
     filename is a new file

new DateRollingFileStream(filename, pattern, options)

filename (String)
pattern (String) - the date pattern to trigger rolling (see below)
options - Object
- encoding - defaults to 'utf8'
- mode defaults to 0644
- flags defaults to 'a'
- compress - (boolean) compress the backup files, defaults to false
- alwaysIncludePattern - (boolean) extend the initial file with the pattern, defaults to false

This returns a WritableStream. When the current time, formatted as pattern, changes then the current file will be renamed to filename.formattedDate where formattedDate is the result of processing the date through the pattern, and a new file will begin to be written. Streamroller uses date-format to format dates, and the pattern should use the date-format format. e.g. with a pattern of "yyyy-MM-dd", and assuming today is August 29, 2013 then writing to the stream today will just write to filename. At midnight, filename will be renamed to filename.2013-08-29 and a new filename will be created. If options.alwaysIncludePattern is true, then the initial file will be filename.2013-08-29 and no renaming will occur at midnight, but a new file will be written to with the name filename.2013-08-30.