Updated: 03 December 2024
Write lines of text to file, with alternating line-ending type: CRLF, LF then finally LF.  Use hexdump to verify the result
echo -n -e \\x61\\x0d\\x0a\\x62\\x0a\\x63\\x0a > file
cat file
hexdump --canonical file
Output
a                                                                    
b                                                                    
c                                                                    
00000000  61 0d 0a 62 0a 63 0a                              |a..b.c.|
00000007                                                             
Vim displays CR as ^M
EditorConfig
end_of_line = crlf
# end_of_line = lf\r\n DOS / Windows – carriage return + line feed.
CRLF DOS / Windows – carriage return + line feed.
0d 0a output of hexdump -C
0xD 0xA alternatively
\n Unix – line feed.
LF Unix – line feed.
0a output of hexdump -C
0xA alternatively
dos2unix
A program that converts plain text files in DOS/MAC format to UNIX format.
Recursively find all files in current directory and run dos2unix on each 
find . -type f -exec dos2unix {} \;unix2dos
A program that converts text files in UNIX format to DOS format.
Convert and replace a.txt. Convert and replace b.txt.
unix2dos a.txt b.txt