SED - Numbering - Add commas to numeric strings

Change “1234567” to “1,234,567”.

gsed ':a;s/\B[0-9]\{3\}\>/,&/;ta'                     # GNU sed
sed -e :a -e 's/\(.*[0-9]\)\([0-9]\{3\}\)/\1,\2/;ta'  # other seds

Add commas to numbers with decimal points and minus signs

gsed ':a;s/\(^\|[^0-9.]\)\([0-9]\+\)\([0-9]\{3\}\)/\1\2,\3/g;ta'