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diff --git a/unix/os/doc/zmain.hlp b/unix/os/doc/zmain.hlp new file mode 100644 index 00000000..3b0c4406 --- /dev/null +++ b/unix/os/doc/zmain.hlp @@ -0,0 +1,62 @@ +.help zmain May84 "System Interface" +.ih +NAME +zmain -- process main +.ih +SYNOPSIS +.nf +not applicable +.fi +.ih +DESCRIPTION +The process main is the procedure or code segment which first gains control +when a process is executed by the host system. The process main must determine +whether the process was called as a connected subprocess, as a detached process, +or by the host system. If spawned as a connected subprocess the standard input +and output of the process are connected to IPC channels leading to the parent +process, otherwise the devices to which the process channels are connected are +machine dependent. + +After connecting the process standard input, standard output, and standard +error output \fBzmain\fR calls the IRAF Main, an SPP procedure. +The calling sequence of the IRAF Main is as follows: + +.nf + main (inchan, outchan, driver, prtype, bkgfile, jobcode) + + int inchan # standard input channel + int outchan # standard output channel + int driver # EPA of device driver for channels + int prtype # process type code + packed char bkgfile[] # name of bkgfile, if detached process + int jobcode # bkg jobcode, if detached process +.fi + +The IPC driver, text file driver, and binary file driver are resident in +every process. The \fBdriver\fR argument is the entry point address of +the read primitive of the appropriate driver, as returned by \fBzlocpr\fR. +The process type code is selected from the following: + +.nf + PR_CONNECTED 1 # connected subprocess + PR_DETACHED 2 # detached subprocess + PR_HOST 3 # process run from host +.fi + +The process type determines the type of protocol to be used by the IRAF Main. +The background file and jobcode are used only if the process was spawned as +a detached process. +.ih +RETURN VALUE +None. +.ih +NOTES +Currently only the CL may be run as a detached process, and only ordinary +SPP processes may be run as connected subprocesses. Either may be run directly +by the host system. The CL uses a nonstandard Main. Error recovery is +handled entirely by the IRAF Main. +.ih +SEE ALSO +zfiopr, zfiotx, and the discussion of the process and IRAF mains in the +reference manual. +.endhelp |