sed "$" not acting as end of line character

Using Ubuntu 18, with the bash shell

The "$" character is not behaving as it should for end of line match in sed.

When I try:

sed '/^>/ s/$/_new/g' <file>

this should result in

>sometext_new

but I am getting

_newetext

This may be related to this question: Error while matching End of line with $ in Sed commandbut that was using csh and had variable assignments which I do not have.

I have tried turning off shell expansion set -f ; but this did not help

I have tried sed '/^>/ s/"$"/_new/g' <file>

this turned $ into a literal character, resulting in no substitution

I would appreciate any help in restoring the previous behaviour of $ as end of line character in sed

1 Answer

Your <file> almost certainly has Windows-style (CRLF) line endings:

$ printf '>sometext\n' | sed '/^>/ s/$/_new/'
>sometext_new

but

$ printf '>sometext\r\n' | sed '/^>/ s/$/_new/'
_newetext

If you want to preserve the CRLF line endings, but replace text at the (Windows) EOL, you could use s/\r$/_new\r/

ex. (piping to cat -A to make the line endings explicit)

$ printf '>sometext\r\n' | sed '/^>/ s/\r$/_new\r/' | cat -A
>sometext_new^M$

OTOH if you want to convert the whole file to Unix endings, you could use

sed -e 's/\r$//' -e '/^>/ s/$/_new/'

or convert the file with dos2unix before using sed.

Note that the g modifier has no effect when a replacement is anchored to the end (or start) of a pattern.