Which client component has to be installed in a custom install on Linux?

The Client API allows applications to directly access the storage services provided by IBM Spectrum Protect, whereas the other options are not necessary for a custom Linux install. However, it's important to note that the specific components required for a custom install may vary depending on the individual needs and requirements of the installation.

https://www.ibm.com/docs/SSEQVQ_8.1.9/client/c_inst.html