You solved my problem.
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I am still learning PHP...
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phpinfo() is the solution... Some discoveries:
My host disables the functions I need to access SPASM, so it didn't work.
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Now I should check this for other hosts.
Your phpinfo() show the info about the system OS and architecture, so I can compile SPASM correctly for it... No need to use shell commands or command line to find this out.
I am more reliefed about the future of the online assembler.