Put the following in your vimrc: if filereadable('/proc/cpuinfo') let &makeprg = 'make -j'.(system('grep -c ^processor /proc/cpuinfo')+1) endif The above command sets the 'makeprg' option using :let to avoid the escaping that would be required if the normal :set command were used. Using :let also allows an expression to be assigned to the option. Vim concatenates make -j and N where N is the number of occurrences of "processor" at the start of a line (^) in file /proc/cpuinfo, plus 1. The output from system() includes a trailing newline, but Vim ignores that when converting the string to a number before adding 1.