Determine the new line character in a text file

text;

given a text, is there a program that can detect what the new line character is, the Windows, Mac, or Linux one?

Eg, the following text is shown by less

memor:^M^Mis storage directly accessible by CPU^M^MThe term "memory"
is often (but not always) associated with addressable semiconductor
memory, i.e. integrated circuits consisting of silicon-based
transistors.^MThe semiconductor memory i s organized into ^Mmemory
cells

I thought ^M is the new line character under Mac.
But in emacs, I searched by Ctrl-q Ctrl-m and found nothing.

Thanks.

Best Answer

file will report on line endings for text files. If you run file on an ASCII Unix/Linux/OSX text file, for example, it will report simply:

$ file test.txt
test.txt: ASCII text

If, however the file has DOS/Windows line-endings, it will instead report:

test.dos: ASCII text, with CRLF line terminators

Up to OS 9, Macs used CR as the line ending. When presented with such a file, file will report:

test.mac: ASCII text, with CR line terminators

With OSX, Macs converted to standard Unix line endings.

Related Solutions

Is the last new line on fstab important

A line is a sequence of characters terminated by a newline character. The characters that appear after the last newline of a file are not part of a line.

Such a file that has characters after the last newline is not a text file as per the POSIX definition of a text file, and the behaviour of text utilities is unspecified in that case and in practice, behaviour varies:

Some ignore those characters completely (skip that non-terminated line)
Some consider it as a line and preserve the absence of newline (like GNU sed)
Some consider it as a line and add back the missing newline (like GNU cut)
Some utilities behaviour changes. Like read which returns a non-zero exit status when reading a non terminated line.

So even if the mount, swapon, fsck... utilities (those which typically read /etc/fstab) understand non-terminated lines, some script that process that file may still fail. You should always make sure text files are terminated by a newline character (unless they're empty). Text editors should do that by default. You generally need to go through hoops to remove that last newline characters.