In Vim, how would I replace the only the first occurrence of a certain word in each line with another word?

Question

For instance, if I had:

eat eat eat eat cake cake

eat eat eat cake

cake eat eat cake

How would I only the first instance of cake in each line with pear?

eat eat eat eat pear cake

eat eat eat pear

pear eat eat cake

Answer 1

Use following

:%s/cake/pear/

Note that if you append 'g' flag to the above expression, the search happens globally over the entire line. The initial '%' character indicates the range over which the replacement should happen. % means whole file (or all lines in the file).

So following does replacement of only first occurrence on each line

:%s/cake/pear/

And following does replacement of all occurrences on each line

:%s/cake/pear/g