Introduction to Linux output

· In the UNIX world, there has been no shortage of typographical and print tools for a long time. For example, the powerful behind-the-scenes typographical system TeX/LaTeX is used to preview, display, and print the file's graphical language Postscript, and the Postscript interpreter Ghostscript, which is common in the Free Software world, along with drivers for printers and other peripheral devices that come with it .... and so on.
· However, it is difficult for these typographical and print tools to process Chinese characters, mainly in the aspect of text encoding methods and fonts. Take Chinese as an example. Because a computer device (such as a printer) or computer software does not have a large number of built-in Chinese fonts with complicated strokes, when we want to output Chinese characters, A special processing method is required. For example, if we want to print a Chinese file of plain text, I cannot directly send it to a pure text printer for printing, because these printers generally do not recognize Chinese encoding and have no fonts available, therefore, it can only be sent to the Chinese encoding into a continuous ASCII or ISO8859-1 encoding, and then its built-in ASCII or ISO8859-1 printed out, the result is printed a series of garbled.
· To solve this problem, we usually do the following for printing, whether it is an orchestration file or plain text: to identify all the text in the file, find the appropriate font for the text part, and draw the font representing the word (or "pattern" for the word) in the file, after the final processing, the original file (or text file) becomes 「Graphic File.. Therefore, in many cases, printing a Chinese text file is actually a graphic file embedded with a Chinese font. There are many formats of graphical files, but in the world of free software, the final output format is generally Postscript.
Graphic Output Format: Postscript and PDF
· Postscript is a descriptive language developed by Adobe and apple in its early years. The reason why Postscript is used as the final printing image format is mainly because it has good portability (because it seems to be a pure text file, rather than a binary file ), in addition, its syntax is highly elastic and scalable, so that we can easily scale the pattern without distortion. At the same time, Postscript is also an important standard for the industry's file output formats. In the early days, many academic papers and typographical printing work eventually output Postscript, and even many printers can read Postscript directly, therefore, they can print Postscript files directly without additional drivers.
· Ghostscript software. It is an interpreter that can understand the Postscript Language. More importantly, it contains many drivers that can convert Postscript files into various forms for output, including many printer drivers, this allows these printers that do not know the Postscript Language to print files smoothly. In addition, Ghostscript also has the X Window drawing module, which allows ghostview and gv programs to display Postscript files in the X Window environment; it can also convert Postscript to other image formats (jpeg, png, tiff ,....), or even faxg3 format that can be sent to a fax .... so, when we want to use a modem to fax a file, we can first prepare the Postscript file of the file, convert it through the Ghostscript program, and then send it out ). Therefore, Ghostscript is a powerful Postscript conversion engine.
· Since Postscript is only a format of image files, it is difficult for us to directly write and modify Postscript files, and we cannot easily search for text in Postscript files, it is more difficult to use the mouse to cut the text in the Postscript file to another window. To make up for these shortcomings, Adobe has developed another set of documents called PDF in recent years. It also contains all the advantages of Postscript (however, it is a binary file, not a plain text file, which is different from the Postscript format), but also makes up for the shortcomings of Postscript, including:
1. Because PDF files haveCompressionSo that it is much smaller than the same Postscript file.
2. When a PDF file is displayed in a PDF browser (such as xpdf), the speed is higher than when a Postscript browser (such as gv) is used to display the Postscript.FastA lot.
3. It is easy to use a PDF EditorDirect ModificationPDF file, you can also directly cut the text in the PDF file to another window.
4. PDF file alsoIndexes supported,Hyper-reference, AndBookmark(Directory.
· Due to these advantages, the general level rate of apsaradb for memcache has rapidly increased over the past one or two years. Many academic documents originally used Postscript have gradually changed to PDF files, even the new version of Ghostscript software in recent years can read the PDF format. However, in the Free Software world, PDF is still not the final output format at present, especially in the aspect of printing tables. In many cases, it is still necessary to convert it into Postscript before printing, however, many plotting programs still provide Postscript rather than PDF printing. I think it will take some time for complete support.