This warning seems to be generated if the script file is not in the current directory. Here is my test script:
The command-line "makensis.exe test.nsi" works properly but if I put the script in a subdirectory and use the command-lineName "Test"
OutFile test.exe
ShowInstDetails show
RequestExecutionLevel "user"
Page instfiles
Section default
DetailPrint "Filename : ${__FILE__}"
DetailPrint "Timestamp: ${__TIMESTAMP__}"
SectionEnd
makensis.exe subdir\test.nsi
then the compiler issues this warning:
unknown variable/constant "{__TIMESTAMP__}" detected, ignoring (subdir\test.nsi:13)
and, of course, the test program displays:
Filename : test.nsi
Timestamp: ${__TIMESTAMP__}
Completed