everest% cc fwrite1.c
everest% 

everest% a.out
10 items were written to the output file
everest% 

everest% ls
a.out*      output      scan1.s     scan3.s     scan5.s     scan7.s
binary      roberts.c   scan2.c     scan4.c     scan6.c     test
fwrite1.c   roberts.s   scan2.s     scan4.s     scan6.s
fwrite1.s   scan1.c     scan3.c     scan5.c     scan7.c
everest% 

everest% file binary
binary:         ascii text
everest% 

everest% cat binary
#*18?everest% 

everest% od -d binary
0000000 00000 00000 00000 00007 00000 00014 00000 00021
0000020 00000 00028 00000 00035 00000 00042 00000 00049
0000040 00000 00056 00000 00063
0000050
everest%