[Wien] hup and nohup in the shell scripts

[Hong Jiang]

Dear Prof. Blaha and Wien2k users,
I am trying to understand how wien2k shell scripts work and come up with 
a few questions.
I notice that in the wien2k shell scripts like run_lapw, it usually 
starts with "hup", and also at the beginning of the scf cycles, it has 
commands like

   nohup echo in cycle $icycle "   ETEST: $etest[3]   CTEST: $ctest[3]"
   hup

I am very confused by these commands.  From the unix manual, I 
understand that "nohup [command] " is used to require  that the command 
to continue to execute after logging out, and "hup" is actually not a 
standard unix shell command. Actually when I run "run_lapw" in the AIX 
system, it gives the message
    hup: Command not found.
and at the end of each cycle it gives
     Sending nohup output to nohup.out.
and the output information about ETEST and CTEST is missing.  But if I 
changes the first line of run_lapw to
    #!/bin/tcsh -f
then everything works fine.

My main question is:  What is the purpose of using "hup" and "nohup" in 
these  shell scripts? Are they really necessary? Thanks a lot in advance!

Best regards,
   Hong