The command file instructs SNAP what to do. It defines the coordinate and data files, the program options, and the output options.
There are about 45 different commands that can be used in the command file. However the only commands that are required are:
title: defining the title of the job
mode: defining what is to be done
coordinate_file: defining the coordinate file
data_file: defining the data to be used
Usually you will also want to specify some stations to be held fixed with the fix command. Here is an example of a command file using just these commands:
title Demonstration SNAP adjustment
!
! The name of the coordinate file.
coordinate_file demo.crd
!
! Data files - in this case there are two
data_file demo.dat
data_file demogps.dat
!
! Do a three dimensional adjustment
mode 3d adjustment
!
! Fix stations TrigX and 1150, and fix the height of
! BM328
fix TrigX 1150
fix vertical BM328