makeworld中一条mergemaster命令不懂的地方？

请问这命令怎么解释，特别是括号的解释。thanks!
/usr/sbin/mergemaster -p -v -w 132 (eliminate '-w 132' if 132x43 video mode is not activated)

-p:Pre-buildworld mode. Compares only files known to be essen-tial to the success of {build|install}world, including/etc/make.conf.


-v :Be more verbose about the process. You should probably use this option the first time you run mergemaster. This option also gives you a list of files that exist only in the installed version of /etc.

-w N:Supply an alternate screen width to the sdiff(1) command in numbers of columns. The default is 80.