Question

I have a regex and replacement pattern that have both been tested in Notepad++ on my input data and work correctly. When I put them into a sed expression, however, nothing gets matched.

Here is the sed command:

 # SEARCH = ([a-zA-Z0-9.]+) [0-9] (.*)
 # REPLACE = \2 (\1)

 sed -e 's/\([a-zA-Z0-9.]+\) [0-9] \(.*\)/\2 \(\1\)/g'

Here is a sampling of the data:

jdoe 1 Doe, John
jad 1 Doe, Jane
smith 2 Smith, Jon

and the desired output:

Doe, John  (jdoe)
Doe, Jane  (jad)
Smith, Jon (smith)

I have tried removing and adding escapes to different characters in the sed expression, but either get nothing matched or something along the lines of:

sed: -e expression #1, char 42: invalid reference \2 on `s' command's RHS

How can I get this escaped correctly?

Answer 1

I usually find it easier to use the -r switch as this means that escaping is similar to that of most other languages:

sed -r 's/([a-zA-Z0-9.]+) [0-9] (.*)/\2 (\1)/g' file1.txt