$ find . -name '*.c' | xargs fold -b1 | sort | uniq -c | sort -nr | head -n20
 346000  
  78512 e
  66030 t
  55989 i
  50620 n
  48712 r
  46259 a
  44977 s
  40413 o
  39771 =
  35981 l
  30273 *
  29555 u
  29542 c
  27341 f
  26719 d
  26258 (
  26257 )
  26003 0
  25119 _