Format-Control Letters
----------------------

   A format specifier starts with the character `%' and ends with a
"format-control letter"; it tells the `printf' statement how to output
one item.  (If you actually want to output a `%', write `%%'.)  The
format-control letter specifies what kind of value to print.  The rest
of the format specifier is made up of optional "modifiers" which are
parameters such as the field width to use.

   Here is a list of the format-control letters:

`c'
     This prints a number as an ASCII character.  Thus, `printf "%c",
     65' outputs the letter `A'.  The output for a string value is the
     first character of the string.

`d'
     This prints a decimal integer.

`i'
     This also prints a decimal integer.

`e'
     This prints a number in scientific (exponential) notation.  For
     example,

          printf "%4.3e", 1950

     prints `1.950e+03', with a total of four significant figures of
     which three follow the decimal point.  The `4.3' are "modifiers",
     discussed below.

`f'
     This prints a number in floating point notation.

`g'
     This prints a number in either scientific notation or floating
     point notation, whichever uses fewer characters.

`o'
     This prints an unsigned octal integer.

`s'
     This prints a string.

`x'
     This prints an unsigned hexadecimal integer.

`X'
     This prints an unsigned hexadecimal integer.  However, for the
     values 10 through 15, it uses the letters `A' through `F' instead
     of `a' through `f'.

`%'
     This isn't really a format-control letter, but it does have a
     meaning when used after a `%': the sequence `%%' outputs one `%'.
     It does not consume an argument.