我嘗試安裝 qpdf 5.1.3；預設版本是 5.1.1（我有 Ubuntu 14.04）。
編譯後從原始碼下載，已安裝版本 5.1.1。的輸出/usr/local/bin/qpdf --version是：
qpdf version 5.1.1
Copyright (c) 2005-2015 Jay Berkenbilt
This software may be distributed under the terms of version 2 of the
Artistic License which may be found in the source distribution. It is
provided "as is" without express or implied warranty.
的輸出apt-cache policy qpdf
qpdf:
Installed: 5.1.3-1
Candidate: 5.1.3-1
Version table:
*** 5.1.3-1 0
100 /var/lib/dpkg/status
5.1.1-1 0
500 fr.archive.ubuntu.com/ubuntu trusty/main amd64 Packages
這很令人困惑，如果我跑
find . -type f -name 'qpdf' -exec {} --version \;
在我得到的來源資料夾中
qpdf version 5.1.1
Copyright (c) 2005-2015 Jay Berkenbilt
This software may be distributed under the terms of version 2 of the
Artistic License which may be found in the source distribution. It is
provided "as is" without express or implied warranty.
qpdf version 5.1.3
Copyright (c) 2005-2015 Jay Berkenbilt
This software may be distributed under the terms of version 2 of the
Artistic License which may be found in the source distribution. It is
provided "as is" without express or implied warranty.
所以似乎編譯了兩個版本。
這是怎麼回事？