Difference between CR LF, LF and CR line break types
I’d like to know the difference (with examples if possible) between CR LF (Windows), LF (Unix) and CR (Macintosh) line break types.
Very similar, but not an exact duplicate. \n is typically represented by a linefeed, but it’s not necessarily a linefeed.
CR and LF are ASCII and Unicode control characters while \r and \n are abstractions used in certain programming languages. Closing this question glosses over fundamental differences between the questions and perpetuates misinformation.
@AdrianMcCarthy It’s a problem with the way close votes act as answers in a way; an answer claiming the two were the same could be downvoted and then greyed out as very, very wrong, but it only takes 4 agreeing votes (comparable to upvotes) to have a very wrong close happen, with no way to counter the vote until after it’s happened.
This formulation of the question is admittedly better, but it is still for all practical purposes the same question.
10 Answers 10
CR and LF are control characters, respectively coded 0x0D (13 decimal) and 0x0A (10 decimal).
They are used to mark a line break in a text file. As you indicated, Windows uses two characters the CR LF sequence; Unix (and macOS starting with Mac OS X 10.0) only uses LF; and the classic Mac OS (before 10.0) used CR.
An apocryphal historical perspective:
As indicated by Peter, CR = Carriage Return and LF = Line Feed, two expressions have their roots in the old typewriters / TTY. LF moved the paper up (but kept the horizontal position identical) and CR brought back the «carriage» so that the next character typed would be at the leftmost position on the paper (but on the same line). CR+LF was doing both, i.e., preparing to type a new line. As time went by the physical semantics of the codes were not applicable, and as memory and floppy disk space were at a premium, some OS designers decided to only use one of the characters, they just didn’t communicate very well with one another 😉
Most modern text editors and text-oriented applications offer options/settings, etc. that allow the automatic detection of the file’s end-of-line convention and to display it accordingly.
so actually Windows is the only OS that uses these characters properly, Carriage Return, followed by a Line Feed.
Would it be accurate, then, to say that a text file created on Windows is the most compatible of the three i.e. the most likely to display on all three OS subsets?
@Hashim it might display properly but trying to run a textual shell script with carriage returns will usually result in an error
Rolf — that statement assumes that keeping old terminology/technology in new technology is correct. CRLF = 2 bytes. CR = 1, LF = 1. With as often as they are used, that actually translates to a huge amount of data. Once again, Windows has chosen to be different from the entirety of the *NIX world.
This is a good summary I found:
The Carriage Return (CR) character ( 0x0D , \r ) moves the cursor to the beginning of the line without advancing to the next line. This character is used as a new line character in Commodore and early Macintosh operating systems (Mac OS 9 and earlier).
The Line Feed (LF) character ( 0x0A , \n ) moves the cursor down to the next line without returning to the beginning of the line. This character is used as a new line character in Unix-based systems (Linux, Mac OS X, etc.)
The End of Line (EOL) sequence ( 0x0D 0x0A , \r\n ) is actually two ASCII characters, a combination of the CR and LF characters. It moves the cursor both down to the next line and to the beginning of that line. This character is used as a new line character in most other non-Unix operating systems including Microsoft Windows, Symbian and others.
The «vertical tab»-character moves the cursor down and keep the position in the line, not the LF-character. The LF is EOL.
@Vicrobot Developers will often split a string or perform other operations with the exact sequence \r\n , so \n\r would not match. Also one would think that text editors also treat the two characters as one sequence and don’t separatly go «oh, now I have to go down one line» and «oh, now I have to move to the front». Were it so then yes, you could freely swap the order around
It’s really just about which bytes are stored in a file. CR is a bytecode for carriage return (from the days of typewriters) and LF similarly, for line feed. It just refers to the bytes that are placed as end-of-line markers.
There is way more information, as always, on Wikipedia.
I think it’s also useful to mention that CR is the escape character \r and LF is the escape character \n . In addition, Wikipedia:Newline.
In Simple words CR and LF is just end of line and new line according to this link , is this correct ?
@shaijut CR stands for Carriage Return. That was what returned the carriage on typewriters. So, mostly correct.
The superior LFCR option is sadly missing. Its benefit is that by doing the Line Feed first, the Selectric golfball can’t smear the just printed line with still fresh ink upon executing the Carriage Return
Actually, it’s not a typewriter but «teletype», old computer client terminals with mechanical print heads and paper, where CR/LF were required for computers to behave properly. If you just did CR, you would have a bunch of characters on top of each other on a paper. If you just did LF, your text lines would slowly migrate to the right on the paper. CR/LF were required for proper teletype based computing. An old Star Trek game would dump «F
Carriage Return (Mac pre-OS X)
Line Feed (Linux, Mac OS X)
Carriage Return and Line Feed (Windows)
If you see ASCII code in a strange format, they are merely the number 13 and 10 in a different radix/base, usually base 8 (octal) or base 16 (hexadecimal).
The \r and \n only works in some programming languages, although it seems to be universal among programming languages that use backslash to indicate special characters.
Jeff Atwood has a blog post about this: The Great Newline Schism
The sequence CR+LF was in common use on many early computer systems that had adopted teletype machines, typically an ASR33, as a console device, because this sequence was required to position those printers at the start of a new line. On these systems, text was often routinely composed to be compatible with these printers, since the concept of device drivers hiding such hardware details from the application was not yet well developed; applications had to talk directly to the teletype machine and follow its conventions. The separation of the two functions concealed the fact that the print head could not return from the far right to the beginning of the next line in one-character time. That is why the sequence was always sent with the CR first. In fact, it was often necessary to send extra characters (extraneous CRs or NULs, which are ignored) to give the print head time to move to the left margin. Even after teletypes were replaced by computer terminals with higher baud rates, many operating systems still supported automatic sending of these fill characters, for compatibility with cheaper terminals that required multiple character times to scroll the display.
Перевод строки
Перевод строки, или разрыв строки — продолжение печати текста с новой строки, то есть с левого края на строку ниже, или уже на следующей странице.
Терминология
Возврат каретки (англ. carriage return, CR) — управляющий символ ASCII (0x0D, 1310, ‘\r’), при выводе которого курсор перемещается к левому краю поля, не переходя на другую строку. Этот управляющий символ вводится клавишей «Enter». Будучи записан в файле, в отдельности рассматривается как перевод строки только в системах Macintosh.
Подача строки (от англ. line feed, LF — «подача [бумаги] на строку») — управляющий символ ASCII (0x0A, 10 в десятичной системе счисления, ‘\n’), при выводе которого курсор перемещается на следующую строку. В случае принтера это означает сдвиг бумаги вверх, в случае дисплея — сдвиг курсора вниз, если ещё осталось место, и прокрутку текста вверх, если курсор находился на нижней строке. Возвращается ли при этом курсор к левому краю или нет, зависит от реализации.
Способы представления
Способ представления перевода строки в текстовом файле часто зависит от используемой операционной системы:
LF ( ASCII 0x0A) используется в Multics, UNIX, UNIX-подобных операционных системах (GNU/Linux, AIX, Xenix, Mac OS X, FreeBSD и др.), BeOS, Amiga UNIX, RISC OS и других;
CR ( ASCII 0x0D) используется в 8-битовых машинах Commodore, машинах TRS-80, Apple II, системах Mac OS до версии 9 и OS -9;
CR+LF ( ASCII 0x0D 0x0A) используется в DEC RT-11 и большинстве других ранних не-UNIX- и не-IBM-систем, а также в CP/M, MP/M (англ.), MS -DOS, OS /2, Microsoft Windows, Symbian OS , протоколах Интернет.
Конвертирование
Способы конвертирования файла:
Файл → Сохранить как… → Конец строки → …
tr -d '\r' dos.file >unix.file tr -d '\015' dos.file >unix.file sed --in-place 's/$/\r/' unix2dos.file sed --in-place 's/\x0d$//' dos2unix.file
What’s the difference between \n and \r\n?
\r is a old pre-OS X Macs Style, Modern Mac’s using POSIX Style.
\r is a carriage return and \n is a line feed, in old computers where it not have monitor, have only printer to get out programs result to user, if you want get printing from staring of new line from left, you must get \n for Line Feed, and \r for get Carriage return to the most left position, this is from old computers syntax saved to this time on Windows platform.
CR+LF is commonly used in many networking protocols (like HTTP), regardless of the OS used to transmit the data. \r is commonly mapped to CR whenever the target system uses ASCII or Unicode as its character system. (If the target system uses EBCDIC, then \r may not have a mapping.) \n is trickier, as it depends on context. It’s often mapped to an ASCII/Unicode LINE FEED, but it’s not always that simple. Answers to the «Possible Duplicate» question has details.
You can see the HTTP spec from here: w3.org/Protocols/rfc2616/rfc2616-sec5.html CRLF (carriage return line feed)
\n means new line. It means that the cursor must go to the next line.
\r means carriage return. It means that the cursor should go back to the beginning of the line.
Unix programs usually only needs a new line (\n).
Windows programs usually need both.
I’m pretty sure you’re wrong and that Windows and Mac behave differently. But since I’m not Mac expert, I’ll remove the line about mac entirely and leave it to more knowledgeable people.
Prior to Mac OS X, Macs used \r alone as its line terminator. As Mac OS X / OS X / macOS is a Unix, the old convention was dropped in favor of the standard Unix convention of a single linefeed.
\n is a newline only, \r\n is a newline and a carriage return (i.e. move the cursor to the left).
‘\n’ is the default in Unix, ‘\r\n’ is the default in Windows.
Different Operating Systems handle newlines in a different way. Here is a short list of the most common ones: DOS and Windows
They expect a newline to be the combination of two characters, namely ‘\r\n’ (or 13 followed by 10).
Unix (and hence Linux as well)
Unix uses a single ‘\n’ to indicate a new line.
so this causes problems when u port your app from windows to mac when u’re using folder path’s and alike.
This is how new line is represented in operating systems Windows (\r\n)and linux (\n)
On Unix the \r is a Carriage Return (CR) and the \n a Line Feed (LF) which together happen to be the be Windows newline identifier and you are replacing them with a Unix newline identifier.
On Windows the \r is a CR, too, but the \n is a combination of CR and LF. So effectively you are trying to replace CR+CR+LF with CR+LF. Doesn’t make much sense, does it.
From «perldoc perlop»: All systems use the virtual «»\n»» to represent a line terminator, called a «newline». There is no such thing as an unvarying, physical newline character. It is only an illusion that the operating system, device drivers, C libraries, and Perl all conspire to preserve. Not all systems read «»\r»» as ASCII CR and «»\n»» as ASCII LF. For example, on a Mac, these are reversed, and on systems without line terminator, printing «»\n»» may emit no actual data. In general, use «»\n»» when you mean a «newline» for your system, but use the literal ASCII when you need an exact character. For example, most networking protocols expect and prefer a CR+LF («»\015\012″» or «»\cM\cJ»») for line terminators, and although they often accept just «»\012″», they seldom tolerate just «»\015″». If you get in the habit of using «»\n»» for networking, you may be burned some day.