Replace second instance a character

Question

I have a file containing several thousand lines, which look something like this:

dm          10:124614405:G_GTR I      .9186   .9829   -0.037   0.964   0.219   0.0283    0.8665     0.0282  0.8665    358       440
dm          10:124685661:TCAAAR D      .9698   .9838    0.239   1.270   0.377   0.4016    0.5263     0.4040  0.525     358       440
dm          rs2280710       C G      .9852   .9924    0.186   1.204   0.899   0.0427    0.8362     0.0418  0.838     165        92

I need to replace the second ":" with a space, throughout the whole document. Normally I would do this with something simple like:

sed 's/:/ /g'

But this will of course replace both colons. I'm not sure how to specify only the SECOND colon be replaced. Any suggestions?

Answer 1

This will replace only the second match on each line:

sed 's/:/ /2'