A carriage return linefeed (CRLF) is a special sequence of characters, used by DOS/Windows, to signify the end of a line of text. However, in *nix, only a linefeed (LF) is required to signify a line ending.
Delete/Replace a Carriage Return (CR) with sed
There are a few ways to remove or replace a carriage return with sed.
sed 's/.$//' test.CRLF.txt > test1.txt
sed 's/\x0D$//' test.CRLF.txt > test2.txt
sed 's/\r//' test.CRLF.txt > test3.txt
The first method assumes all lines end with CRLF, while the second and third method depend on the version of sed.
Delete/Replace a Linefeed (LF) with sed
By default, sed strips the newline as the line is placed into the pattern space. However, the workaround is to read the whole file into a loop first.
:a - create a label 'a'
N - append the next line to the pattern space
$! - if not the last line
ba - branch (go to) label 'a'
s - substitute
/\n/ - regex for new line
/<text>/ - with text "<text>"
g - global match (as many times as it can)
Example: Delete Newlines (CRLF) with sed
Delete the carriage return first, and then delete the linefeed.
sed -i 's/\r//g' example.txt
sed example delete newline carriage return.png
sed -i ':a;N;$!ba;s/\n/<text>/g' example.txt
sed example delete newline linefeed.png
tr: A Simpler Way to Replace or Delete a Newline (CRLF)
The tr utility is a preferred and simpler method for replacing end of line characters as the pattern buffer is not limited like in sed.
tr '\r\n' '<replace with text>' < input_file > output_file
or to delete the newline (CRLF),
tr -d '\r\n' < input_file > output_file
\r - carriage return
\n - linefeed
Example: Delete Newlines (CRLF) with tr
tr -d '\r\n' < example.txt > example2.txt
tr example delete newline CRLF.png
Command Line Examples
Note: The command cat will concatenate files and print on the standard output. The option A will use ^ and M notation to show non-printing characters, display $ at end of each line, and display TAB characters as ^I.