How do I prefix all the lines in a file with the corresponding line

numbers? You can prefix the lines in a file with the corresponding line number in several ways. Some of them are listed below:

    :%s/^/\=line('.'). ' '

    :%s/^/\=printf('%5d ', line('.'))/

    :%s/^/\=strpart(line('.').'.     ', 0, 5)

    :%s/^/\=strpart('   ', strlen(line('.'))).line('.').'. '

The last two commands will pad the line numbers with space characters. The last command will right align the numbers and the command before that will left align the numbers. If you don’t want to number consecutive lines but rather non-consecutive regions, you can also use this idiom:

    :let i = 1

    :g/TODO/s/^/\=printf('%2d.',i)|let i+=1

This first initializes the variable i with 1. In the next line, a :g command is used to perform a substitute command only on lines, that match ‘TODO’. After the substitute command has taken place, the variable i will be incremented by 1.