Using sed to translate dos line ends to unix line ends.

Question

Here is my first attempt at translation. I read in the sed man page how \ acts differently, but I see references to \r etc.
I have a text file. I do not know if it has \r\n or \r as line ends.
so I want to
change \r\n to \n
then change \r to \n
Thus I end up with unix line ends.
mac $ echo -ne  "1\r\n2\r\n" | sed "/\r\n/\n/g"
sed: 1: "/\r\n/\n/g": invalid command code \
mac $ 
I left out the Mac conversion of \r to \n.
I did a google search looking for the conversion. Lots of attempts at conversion. Lots of people eliminated the \r, that wasn't my idea. I moved to Perl after giving up on sed. Thanks everyone who read & responded to my previous Perl post.
Robert

Answer 1

Cole Tierney wrote:
Sed on linux will honor carriage returns entered as
. BSD sed does not appear to. I've confirmed this on Mac OS 10.3.9 and 10.4.11. On those systems you need to enter a carriage return as a literal using control-v control-m. The carriage return is then displayed as ^M. This can be confusing in forums since people will try to enter it as it is displayed (shift-^ shift-m).
I was unfamiliar with this method of escaping. I saw references to this in my Google search. I am using the commands in an
Applescript, so I didn't know how to enter.
http://discussions.apple.com/edit!default.jspa?messageID=12681001
My work around is to let bash deal with the carriage return using $'
'. The trade off is you then have to look at a lot of single quotes. I find it easier to think of it in a couple steps. To expose the $'
' to bash you first split the sed with a couple single quotes at the point where you want the carriage return to appear.
sed 's///' <- initial
sed 's/''//' <- split
sed 's/'$'
''//' <- insert
</div>
I didn't know about this use of $.
If were dropping down to bash, then what is the deal with this:
mac $ echo -ne  "1
2
" | sed  's/'"
"'//' | hexdump
0000000 310d 0a32 0d0a                         
0000006
I thought double quotes escaped things.
The input for your second example has a line with more than one carriage return. My sed only deletes one carriage return per line. Another option is to anchore the match at the end:
sed 's/'$'
''$//'
I saw the linux version of this, but didn't see the trick of the $ forcing line end and the linux version didn't work for me on Tiger.
This ends my quest for a tiger version of sed.
(( At least for DOS, I think I'll forget the classic version of Mac OS. ))
Thanks.
Robert