GNU Barcode is a tool to convert text strings to printed bars. It supports a variety of standard codes to represent the textual strings and creates postscript output. Main features of GNU Barcode:

Available as both a library and an executable program Supports UPC, EAN, ISBN, CODE39 and other encoding standards Postscript and Encapsulated Postscript output Accepts sizes and positions as inches, centimeters, millimeters Can create tables of barcodes (to print labels on sticker pages)