web2png - convert a web tree from using GIFs to using PNGs
web2png [-adnrtv] [directory...]
Web2png is a front end for gif2png(1) that automatically converts entire web page hierarchies from using GIFs to using PNGs. It does image conversion and patches IMG SRC references in web pages. The arguments to web2png must be directories; if none are given, the current directory is assumed. In each directory, web2png tries to convert every GIF to a PNG. It leaves alone GIFs that have multiple images, because these will not display properly in all current browsers. It also does not reconvert GIFs that already have corresponding PNGs (e.g. the same name except for the .gif file extension). The original GIFs are left in place. Web2png tracks successful conversions. It then looks at each HTML, secure HTML, HTML inclusion, PHP page, JavaScript program or Cascading Style Sheet under the argument directories (extensions html, shtml, .inc, .php, .js, .css). In these pages, it fixes each reference to each successful converted GIF to point at the PNG. References in relative HREF and BACKGROUND tags are recognized by filename and fixed (any base directory declared by a BASE tag will be be prepended to the relative URL). References that are HTTP URLs are matched against the list of convertible GIFs by basename; if there is such a match, the contents of the URL is retrieved and compared to the convertible GIF. If both basename and data match, the HTTP reference is fixed. If the pages are under RCS version control, they're checked out for modification before being altered; otherwise, a copy of the original of each modified web page is left in the same directory, with the additional extension .bak. The following options change the behavior of the program: -a Convert all GIF files, including those with multiple images. -d Delete originals. Removes all GIFs with corresponding PNGs, and all .bak files. -n Make no changes. With this option, web2png reports on what needs to be done (and on GIFs that have multiple images), but neither converts GIFs nor touches web pages. -r Reverse. Restore all HTML/SHTML/PHP pages from the .bak files created by a previous run (or, if the files were under version control, revert them). Remove PNGs with corresponding GIFs. -v Verbose. Utter more trace information about the conversion process. Web2png can be run on a directory that has already been partly converted by previous runs; it will do the minimum necessary amount of work. The changes it makes will be fully reversible with -r until you run it in -d mode. Web2png is written in Python. Python 1.5.2 or better must be installed and accessible on your system in order for web2png to run.
Sometimes it's possible to convert transparent GIFs without altering the appearance of the page, by knowing from context that they will always place within an area of fixed and solid color. Web2png can't deduce when this will be, so it doesn't try; but it may be useful to apply gif2png with the -b option by hand.
The algorithm for fixing HTTP URLs is not foolproof. It could be confused into incorrectly patching an HTTP URL reference to a GIF into an invalid reference to a PNG if the GIF matches a local target GIF by both basename and binary content, but actually lives on another host. This program does not automatically convert CGIs; you'll have to do that by hand. Other dynamic-content methods (such as server-side inclusions) may also require hand-hacking. The program cannot tell converted from preexisting PNGs; if you have PNGs with the same stem name as corresponding GIFs but carrying different information, the -r mode will clobber them.
gif2png(1)
Eric S. Raymond <esr@thyrsus.com>, October 1999. Slightly modified for Debian by Aaron Isotton <aaron@isotton.com>.
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.