sed Delete / Remove ^M Carriage Return (Line Feed / CRLF) on Linux or Unix

Posted on in Categories , , , , , , , last updated June 3, 2016

How can I remove the ^M or ^M (carriage Return / line feed ) from text file using sed under UNIX or Linux operating systems?

A newline is nothing but end of line (EOL). It is a special character or sequence of characters signifying the end of a line of text and the start of a new line. The actual codes representing a newline vary across operating systems. For example CR+LF is used by Microsoft Windows, DOS (MS-DOS, PC DOS, etc.). LF is used by Unix and Unix-like systems including Linux, OS X, FreeBSD and more. The procedure is as follows:

  1. Type the following sed command to delete a carriage Return (CR)
  2. sed 's/\r//' input > output
  3. Type the following sed command to replace a linefeed(LF)
  4. sed ':a;N;$!ba;s/\n//g' input > output

Delete a carriage return (CR) with sed command

The substitute command syntax is as follows (to get ^M type CTRL+V followed by CTRL+M i.e. don’t just type the carat symbol and a capital M. It will not work):

sed -e 's/^M//g' input
sed -e 's/^M//g' input > output
# gnu sed syntax
sed -i 's/^M//g' input
# replace it with FOO
sed -i -e 's/^M/FOO/g' input

OR easy to use sed syntax to remove carriage return in Unix or Linux:

sed 's/\r$//' input > output
sed 's/\r$//g' input > output 
# GNU/sed syntax
sed -i 's/\r$//g' input

To replace a carriage return (CR) with sed command

The syntax is:
sed 's/\r/YOUR-replacement-TEXT-HERE/' input > output
sed 's/\r/YOUR-replacement-TEXT-HERE/g' input > output
sed 's/\r/foo/g' input > output

How to verify ^M in a text file

Use the cat command as follows:
cat -v input
Sample outputs:

Fig.01: cat and sed command in action to delete carriage returns and linefeeds (CRLF)
Fig.01: cat and sed command in action to delete carriage returns and linefeeds (CRLF)

A note about deleting or replacing a linefeed (LF) with sed on Unix or Linux

Use the following syntax if you do not want to delete \n (new line):
sed -i ':a;N;$!ba;s/\n//g' input
OR
sed ':a;N;$!ba;s/\n//g' input > output
See sed command man page for more info.

Remove a carriage return with dos2unix command

You can also use dos2unix command to converts text files from the DOS format to the Unix format:

dos2unix input
dos2unix -b input

The tr command syntax

To delete a CRLF:
tr -d '\r' < input > output

23 comment

  1. On my version of sed, GNU sed 4.2.1, the above command sets perform quite differently:

    sed ‘/^M/d’ input removes the lines with ^M in them, whereas
    sed ‘s/^M//’ input removes just the ^M from the lines.

    The latter was the desired behaviour in my case, I hope this helps.

  2. In some cases I had to check that all files have no carriage return at the end of the line.

    With the command “be” this task although it seems somewhat labored is greatly facilitated.

    I leave here the statement that I use for this purpose:

    #tested with GNU sed
    sed -e '/^M/d' -i -r $(find . -type f)
    
  3. Hi
    Try this example: sed “s/\^M//g” testfile >testfile.out.
    It is important to put a Backslash to protect the ^M charactar!
    cheers and have a nice day ;-)

  4. For those of you saying this doesn’t work, I think I might have your answer. Please note this line in the article:

    “Type the following command (to get ^M type CTRL+V followed by CTRL+M):”

    You can’t just type the carat symbol and a capital M. You have to hit CTRL-V and then hit CTRL-M. I had quite a time figuring that out….but once you do it right, it works great.

    1. You’re right bogus,

      Personnally, I tried with copying-pasting the expression and it failed.
      We’ve got to type literally the keys sequence that you notice.

      Thanks !

  5. bogus, no, that didn’t work either. This really doesn’t work.
    I tried \{CTRL-V}{CTRL-M} inside my sed command’s string and that didn’t work
    I also tried {CTRL-V}{CTRL-M} without the \ and that didn’t work either.
    It does not find the carriage return on a Mac. You’re right that {CTRL-V}{CTRL-M} shows up as ^M and the cursor moves across both characters at once so it’s definitely treated as a CR instead of {Carat}{M} but sed on the Mac will not find it.

    Does anyone else have any ideas?

  6. Thanks for the tr method Valentin. It works and doesn’t require entering the actual CR code so it can be cut and pasted.

    tr -d ‘\r’

  7. Not every system has dos2unix installed on it.. and sometimes you are working on unix boxes and creating scripts because you administer an application on it, but are not the unix administrator yourself (and they won’t install it :D )

    it’s good to talk about ways to do things without 3rd party tools, just in case you don’t have them.

  8. I see it’s really old tutorial – but still on google is quite high in search results..

    The safets way to replace carraige sign is just by using ascii codes..

    sed -i 's|[\d13]||g' Input_file

    or

    sed 's|[\d13]||g' IN > OUT

  9. Osx uses freeBSD’s SED, which is not the Same as the GNU version of SED found on many Linux distros. The little differences can be really maddening. you can install the GNU version to make this syntax work. Google ‘install GNU SED on osx ‘

  10. There are two example of removing the CR:

    sed ‘s/\r//’ input > output

    sed ‘s/\r$//’ input > output

    What does the $ signify in the 2nd example?

      1. Thank you.
        Does that mean that the first one will remove the CR from anywhere in the line and the 2nd will only remove it from end-of-line?

        I notice the comment above the 2nd example said:
        “OR easy to use sed syntax to remove carriage return in Unix or Linux:”
        And the only difference was the “$” inclusion. Is that significant?

Leave a Comment