Using sed with e substitution option: s///e

Question

I'm having a problem using the sed substitution option that executes a command in the replacement pattern. I believe the option is an extensions to GNU sed but I haven't been able to find any documentation on it. Anyone know of any?

My problem is that I can't extract the matching text properly when using the execute replacement option. I'm using GNU sed 4.2 on Mac OSX 10.7.4

echo "12345678\r" | sed 's/.*/echo "&);"/e'

Result: );345678
Desired Result: 12345678);

I've tried using different regex matches, such as \d+, but that just seems to break the ability to use the /e substitution option. And I've tried using an explicit capture group such as \1 instead of & but that also seems to break the /e option.

Update:

My example was perhaps oversimplified what I'm ultimately trying to do is take a text file with each line holding a unique value and pass that to sed and use the uuidgen command (in the same manner as a previous question I posted). The new problem I've got is because I'm now running the command on a Mac the \r is not being stripped from the matched string.

The full command I want to execute is:

sed 's/.*/echo "blah blah `uuidgen`,&):"/e' file.txt

Update 2:

In my Mac terminal I don't need to use echo -e to get \r interpreted as a line feed and in fact according to "man echo" there is no -e option. It does make life difficult moving between all the terminal environments :(.

Thanks to kev I was able to come up with a solution that worked on Mac.

sed 's/\r//; s/.*/ echo "blah blah (`uuidgen`,&);"/e' file.txt

The `e` option is documented in the [GNU `sed` manual](http://www.gnu.org/software/sed/manual/sed.html#The-_0022s_0022-Command). — Jonathan Leffler, Jun 26 '12 at 01:11

kev · Accepted Answer · 2012-06-26T00:40:43.737

2

Remove the e flag:

$ echo "12345678\r" | sed 's/.*/echo "&);"/'
echo "12345678\r);"

Add e flag is the same as:

$ echo -e "12345678\r);"
);345678

You can remove the \r:

$ echo "12345678\r" | sed -e 's/\\r//' -e 's/.*/echo "&);"/'
12345678);

edited Jun 26 '12 at 00:40

answered Jun 26 '12 at 00:29

kev

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The \r is what I'm trying to cope with in the real input to the sed command. – sipsorcery Jun 26 '12 at 00:34
The two stage sed command sorted it for me, I should have thought of that. – sipsorcery Jun 26 '12 at 01:01
Why is the `\r` present at all? Data from Windows? Convert to Unix before processing. Consider using the `tr` command to remove the `\r`. – Jonathan Leffler Jun 26 '12 at 01:14
Yes the file is from Windows. How do you apply tr to a stream? The sed approach of s/\r// was perfect. – sipsorcery Jun 26 '12 at 01:23

score 2 · Answer 2 · answered Jun 26 '12 at 00:53

);345678

What echo outputs is 12345678 followed by \r which takes the cursor back to beginning of line and the ); resulting in the string you see in the window. Put a |od -cx at the end of command to see.

On my cygwin install I need echo -e to get the similar behavior. I am not able to remove \r in sed but I am able to do by adding tr:

$ echo "12345678\r" | sed 's/.*/echo -e "&);"/e'| tr -d "\r"
12345678);

Using sed with e substitution option: s///e

2 Answers2