waitpass [ parameter=value ]
Parameter is: pass_number.
When tsched initiates pass reception, it starts three jobs: rdframe, antenna if antenna control is indicated, and a post-process as indicated by the schedule. All three jobs run simultaneously. tsched sets the environment variable LASTPASS to the 1-relative number of the pass partition used to hold the incoming pass data.
The post-process can choose to ingest the pass data directly from shared memory while it is being framed by rdframe. Or, if live ingest is not necessary, waitpass can be used by the post-process to wait until rdframe has finished before continuing.
Because tsched starts up rdframe and the post-process at the same time, it is important for the post-process not to get ahead of rdframe. Whether or not waitpass is used, the first line of the post-process script should be sleep for a few seconds. A typical post-process script might start like:
sleep 5
waitpass pass_number=$LASTPASS
waitpass works by looking at flags in antenna shared memory, SHMEM_ACC, and the online catalog, onlinecat. waitpass waits while capture flag in the online catalog shows busy, and while the rdframe process id field in antenna shared memory is non-zero. The sleep step mentioned above gives rdframe a chance to put its process id into antenna shared memory.
Last Update: $Date: 1999/05/10 20:46:57 $