Source: http://stackoverflow.com/questions/1251999/how-can-i-replace-a-newline-n-using-sed

Replace with space:

Use this solution with GNU sed:

someoutput | sed ':a;N;$!ba;s/\n/ /g'

Here is cross-platform compatible syntax which works with BSD sed (FreeBSD 8 confirmed):

someoutput | sed -e ':a' -e 'N' -e '$!ba' -e 's/\n/ /g'

Replace with double dash:

Use this solution with GNU sed:

someoutput | sed ':a;N;$!ba;s/\n/--/g'

Here is cross-platform compatible syntax which works with BSD sed (FreeBSD 8 confirmed):

someoutput | sed -e ':a' -e 'N' -e '$!ba' -e 's/\n/--/g'