cmake run script for install target?

This worked for me: use add_custom_target, then add the main target as a dependency to the custom target target.

# create custom target for setcap to be executed
add_custom_target(setcap ALL
    WORKING_DIRECTORY ${OUTPUT_DIR}/bin
    COMMAND ${CMAKE_COMMAND} -E 'sudo setcap cap_net_raw,cap_net_admin+eip ${}/bin/<executable name>)
# create a dependency on the custom target for main target, setcap depends on ${proj_name}
add_dependencies(setcap ${proj_name})

CMake's install command allows for custom scripts. See the official documentation: install - Custom Installation Logic:

install([[SCRIPT <file>] [CODE <code>]]
        [COMPONENT <component>] [...])

The SCRIPT form will invoke the given CMake script files during installation. If the script file name is a relative path it will be interpreted with respect to the current source directory. The CODE form will invoke the given CMake code during installation. Code is specified as a single argument inside a double-quoted string. For example, the code

install(CODE "MESSAGE(\"Sample install message.\")")

will print a message during installation.

To run custom shell script (or whatever program), combine install(CODE ...) with execute_process:

install(CODE "execute_process(COMMAND my_script.sh)")