Having header fields on data means that there are many additional pieces of information to be kept track of, besides just the seismic data, themselves. If you read data from a SEGY format tape, segyread will preserve the trace header information in the main part of the SEGY header. We saw above that surange would permit us to see the min and max header values over an entire dataset. However, we often need to see the values of trace header fields, trace by trace, and in an order that we choose.
The program sugethw (pronounced, SU get header word) is just such a utility. For example, the command sequence:
% sugethw < data.su key=keyword1,keyword2,... | moreWill dump the values of each of the header fields specified by the keywords listed.
A more tangible example, using suplane data input via a pipe is
% suplane | sugethw key=tracl,tracr,offset,dt,ns | more tracl=1 tracr=1 offset=400 dt=4000 ns=64 tracl=2 tracr=2 offset=400 dt=4000 ns=64 tracl=3 tracr=3 offset=400 dt=4000 ns=64 tracl=4 tracr=4 offset=400 dt=4000 ns=64 tracl=5 tracr=5 offset=400 dt=4000 ns=64 tracl=6 tracr=6 offset=400 dt=4000 ns=64 tracl=7 tracr=7 offset=400 dt=4000 ns=64 ...There is no requirement regarding the order of the key words specified, or the number of keywords, as long as at least one is specified.
If, for some reason, you need to dump the values in binary format, an example, again using suplane data
% suplane | sugethw key=tracl,tracr,offset,dt,ns output=binary > file.binoutputs the values sequentially in order of keyword given, trace by trace.
For ``geometry setting,'' you may want to use a command sequence (again illustrated by piping suplane data into sugethw)
% suplane | sugethw key=tracl,tracr,offset,dt,ns output=geom > hdrfile
The contents of hdrfile may be viewed via
% more hdrfile 1 1 400 4000 64 2 2 400 4000 64 3 3 400 4000 64 4 4 400 4000 64 5 5 400 4000 64 ...where only the first 5 rows of data have been shown.