Here are some examples of using tjoin:
stilts tjoin nin=2 in1=positions.fit in2=fluxes.fits out=combined.fits
stilts tjoin nin=3 fixcols=all \
ifmt1=ascii in1=t1.txt suffix1=_T1 \
ifmt2=ascii in2=t2.txt suffix2=_T2 \
ifmt3=ascii in3=t3.txt suffix3=_T3 \
ocmd='select FLAG_T1==0' \
omode=stats