接下來要做的是install world。
# cd /usr/src # make installworld
最後是mergemaster -iU。
# mergemaster -iU
*** Unable to find mtree database. Skipping auto-upgrade.
*** The directory specified for the temporary root environment,
/var/tmp/temproot, exists. this can be security risk if untrusted
users have access to the system.
Use 'd' to delete the old /var/tmp/temproot and continue
Use 't' to select a new temporary root directory
Use 'e' to exit mergemaster
Default is to use /var/tmp/temproot as is
How should I deal with this? [Use the existing /var/tmp/temproot]
請按Enter鍵繼續。
mergemaster主要會把系統相關的設定檔做比對，因為我們已經更新了系統，所以有些舊的設定檔就不適用了，遇到設定檔有新舊版本的差異時，mergemaster會列出相異的地方，並且停下來。這時候就一直按Space鍵，直到類似以下的選項出現：
Use 'd' to delete the temporary ./etc/defaults/rc.conf Use 'i' to install the temporary ./etc/defaults/rc.conf Use 'm' to merge the temporary and installed versions Use 'v' to view the diff result again Default is to leave the temporary file to deal with by hand How should I deal with this? [Leave it for later]
像以上這個訊息表示新版本的/etc/defaults/rc.conf和系統原有的內容不一樣，這時候：
| 輸入 | 代表意義 |
| d | 刪除新版本，保留舊版本。 |
| i | 安裝新版本。 |
| m | 合併新舊二個版本。 |
| v | 再看一次剛才看過的檔案比對結果 |
通常都是輸入i就可以了。
mergemaster比對完所有的設定檔後，就會出現以下的訊息：
*** Comparison complete Do you wish to delete what is left of /var/tmp/temproot? [no]
這是問我們要不要把那些暫存檔案清除，可以輸入yes。
Do you wish to delete what is left of /var/tmp/temproot? [no] yes
*** /var/tmp/temproot has been deleted
*** You chose the automatic install option for files that did not
exist on your system. The following were installed for you:
/etc/rc.d/FILESYSTEMS
/root/.cshrc
以上的訊息是因為下達mergemaster時有加-i的參數，所以原本系統上缺少的檔案就會自動被安裝。不過由於我們已經設定過/etc/csh.cshrc，所以不需要/root/.cshrc，可以刪除它
# rm /root/.cshrc
重新開機，大功告成。
# reboot
Waiting (max 60 seconds) for system process `vnlru' to stop...done
Waiting (max 60 seconds) for system process `bufdaemon' to stop...done
Waiting (max 60 seconds) for system process `syncer' to stop...
syncing disks...0 0 done
All Buffers synced.
Uptime: 3h59m59s
Rebooting...