UNIX for Dummies Questions & Answers

I know that windows uses CRLF as a end of line character while Unix uses LF. But visually i could not see any difference in files while creating on either of plat forms.

CR (Carriage Return) means to bring cursor to beginning of line while LF (Line feed) means to bring cursor to next line without modifying its position.

Now when i hit enter on a file in windows, end of line is represented by CRLF, that's why i see the cursor at the beginning of next line. Now in unix also when i hit enter i see cursor on the beginning of next line but unix uses line feed only and not carriage return.

I am confused with this. Is there any way to visualize these? what additional benefit we are getting using CR in windows in addition if same result can be obtained using Line feed only.

Thanks
Sarbjit

Use wordpad instead of notepad :

Wordpad will recognize if your file only has LF and will give a nice display ... notepad won't.

If CRLF formatted file, both notepad and wordpad will display it correctly.

It is a historic design issue error in some early Operating systems, many of which precede Microsoft. Early printer-terminals were either real Teletypes or similar emulations of a typewriter.
Before proper printer drivers you used to print a file by copying it straight to the printer port down a serial cable. It needed the carriage-return character to print correctly.
Later printers had a dipswitch to optionally tell the printer to treat a linefeed as a carriage-return-line-feed.
The first PC which I came across with text files with carriage-return-line-feed as a text file record terminator was running Digital Research CP/M . The contemporary forerunners of modern unix did not have this issue.

In the modern world it still matters. You are best advised to use unix-format text files on unix and MSDOS format text files on Microsoft O/S because much software expects this.

Another way to look at it is as follows:

CR-LF are the actual bytes that would be sent over a serial port to most terminal devices. Microsoft, originally with DOS, chose to put those characters into a text file to mark end of line.

The Unix creators decided to instead use a single character to logically represent and end of line, call a New Line or NL, which somewhat coincidentally is the same byte code as a line-feed. It could actually have been anything as it need not have anything to do with the bytes actually sent to a terminal.

It's just a different philosophy. It might help if you think of the byte in Linux as a NL, not as a LF.

It's really the program that is READing your file that interprets the LF or CR. Early when teletypes were system consoles, they needed more control, such as when someone logged in, they had to mask the password, so the system used CR, typed a string, then CR again typed another string, so it ended up a virtual black line. When Dot matrix was used, they knew which characters used each pin and could cover it a a couple of passes.

But it goes back to whose using it, most disk drives contain the number of bytes in the file, for example, you could have an executable with a byte(s) or CR or LF or CRLF. In which case it could be data or an instruction. In this case the OS would read data, length specified in the load module, from the disk, and load it to a specified location or let the OS move it to where it could run, then also in the data is an offset to execute, so the machine knows where to start the program. Writing in Assembly code, you can put data and code anywhere, then specify the starting point.

So in your instance it boils down to 'whose reading it'!

Hope this will help some....

Notepad++ | 5.9
Also handles unix files, and has some other nice features.