Split numbers using stream editor (sed)

Question

I want to insert periods as thousands separators using sed. How can I do that?

Sample imput/output:

29371923471239 -> 29.371.923.471.239

Answer 1

Try this

echo "29371923471239" | sed -r ':A;s|([0-9]+)([0-9]{3})|\1,\2|g;t A'
29,371,923,471,239

This works by splitting the number into two parts, the last 3 digits and everything else. It then adds a , to the end of everything else and branches back to the start. You can see this working with

echo "29371923471239" | sed -r ':A;s|([0-9]+)([0-9]{3})|\1,\2|g'
29371923471,239

Answer 2

USE GHC-ONELINERS FOR A GREAT GOOD

$> echo -n 29371923471239 | ghc -e "import Data.List.Split" -e "putStrLn . reverse . intercalate \".\" . splitEvery 3 . reverse =<< getContents"
29.371.923.471.239

!

Answer 3

From: http://www.linuxtopia.org/online_books/linux_tool_guides/the_sed_faq/sedfaq4_007.html

sed -e :a -e 's/\(.*[0-9]\)\([0-9]\{3\}\)/\1,\2/;ta'

echo "981273981723" | sed -e :a -e 's/\(.*[0-9]\)\([0-9]\{3\}\)/\1,\2/;ta' 981,273,981,723