sachd [sac-file ...]
lemond% sachd < /home/ruper/levshin/CANADA/April/931016/931016.FCC.sac SAC Non-NULL header values: delta = 1.000000 time increment, sec depmin = -693676.875000 minimum amplitude depmax = 856146.125000 maximum amplitude b = 0.000000 initial value, ampl. e = 3599.000000 final value, amplitude o = -1769.000000 event start, sec > 0 internal1 = 2.000000 internal use stla = 58.762001 station latititude stlo = -94.086998 station longitude stel = 39.000000 station elevation, m stdp = 0.000000 station depth, m evla = -5.700000 event latitude evlo = 145.800003 event longitude evdp = 33.000000 event depth dist = 12244.426758 stn-event distance, km az = 28.697292 event-stn azimuth baz = 293.521942 stn-event azimuth gcarc = 110.144539 stn-event dist, degrees depmen = 46138.996094 mean value, amplitude cmpaz = 0.000000 component azimuth cmpinc = 0.000000 component inclination nzyear = 1993 zero time of file, yr nzjday = 289 zero time of file, day nzhour = 3 zero time of file, hr nzmin = 35 zero time of file, min nzsec = 0 zero time of file, sec nzmsec = 0 zero time of file, msec internal4 = 6 internal use internal5 = 0 internal use internal6 = 0 internal use npts = 3600 number of samples iftype = 1 type of file iztype = 9 zero time equivalence leven = 1 data-evenly-spaced flag lpspol = 0 station polarity flag lcalda = 1 calc distance, azimuth unused27 = 0 reserved for future use kstnm = FCC station name kcmpnm = BHZ component name First 12 data samples: 26647.222656 -127440.078125 -40447.789062 126147.835938 105347.265625 22891.560547 60291.769531 170846.656250 -32694.488281 -143943.968750 -17369.126953 113700.882812
Look at libsac.h and the libsac.a library source code.