To create a package using a specific format, it is possible to pick the Generator to be used.
Similar to CMake this may be done using the -G argument:
cpack -G 7Z .
Using this command line would package the built project in the current directory using the 7-Zip archive format.
At the time of writing, CPack version 3.5 supports the following generators by default:
7Z
7-Zip file format (archive)IFW
Qt Installer Framework (executable)NSIS
Null Soft Installer (executable)NSIS64
Null Soft Installer (64-bit, executable)STGZ
Self extracting Tar GZip compression (archive)TBZ2
Tar BZip2 compression (archive)TGZ
Tar GZip compression (archive)TXZ
Tar XZ compression (archive)TZ
Tar Compress compression (archive)WIX
MSI file format via WiX tools (executable archive)ZIP
ZIP file format (archive)If no explicit generator is provided, CPack will try to determine the best available depending on the actual environment. For example, it will prefer creating a self-extracting executable on Windows and only create a ZIP archive if no suitable toolset is found.