Your question is really ´How can I know a process is running and get information about it?´. For this question a database is a poor solution. A still poorer solution is a PID-File. The best solution would be a FIFO, aka named pipe. Because every process closes its filedescriptors at the end of its run (even if SIGKILLED) and a FIFO behaves different if its open by another process, you can surely detect if a process is running. Steps to take:
  • Exclusively gain access to the FIFO(done with another FIFO)
  • Stat FIFO: if empty no process
  • Open FIFO
  • Read FIFO
  • Write back to FIFO
  • Close FIFO
  • Give up exclusive access
    • The Server does only:
  • Exclusively gain access to the FIFO(done with another FIFO)
  • Open FIFO
  • Write PID to FIFO
  • Not close FIFO
  • Give up exclusive access

    • In reply to Re: Signals and END block by Anonymous Monk
    in thread Signals and END block by Marcello

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