官网:
https://www.pdflabs.com/tools/pdftk-server/
After installation, open a Terminal, type pdftk and press Return. Pdftk will respond by displaying brief usage information(注意!安装后请试试这一步,出现使用说明说明安装成功)
. Access pdftk documenation by running man pdftk.
This installer creates a directory on you Mac: /opt/pdflabs/pdftk/. This will contain a bin directory which holds the pdftk program and a docs directory which holds the complete PDFtk manual.