通用数字排序将数字比较为浮点数，这允许科学记数法例如1.234E10，但是更慢，并受舍入误差(1.2345678可能来自1.2345679之后)，数字排序只是一个常规的字母排序，知道10后9。
‘-g’ ‘–general-numeric-sort’
‘–sort=general-numeric’ Sort
numerically,using the standard C
function strtod to convert a prefix of
each line to a double-precision
floating point number. This allows
floating point numbers to be specified
in scientific notation,like 1.0e-34
and 10e100. The LC_NUMERIC locale
determines the decimal-point
character. Do not report overflow,
underflow,or conversion errors. Use
the following collating sequence:
Lines that do not start with numbers
(all considered to be equal). NaNs
(“Not a Number” values,in IEEE
floating point arithmetic) in a
consistent but machine-dependent
order. Minus infinity. Finite
numbers in ascending numeric order
(with -0 and +0 equal). Plus
infinity.
Use this option only if there is no
alternative; it is much slower than
–numeric-sort (-n) and it can lose information when converting to
floating point.
‘-n’ ‘–numeric-sort’ ‘–sort=numeric’
Sort numerically. The number begins
each line and consists of optional
blanks,an optional ‘-’ sign,and zero
or more digits possibly separated by
thousands separators,optionally
followed by a decimal-point character
and zero or more digits. An empty
number is treated as ‘0’. The
LC_NUMERIC locale specifies the
decimal-point character and thousands
separator. By default a blank is a
space or a tab,but the LC_CTYPE
locale can change this.
Comparison is exact; there is no
rounding error.
Neither a leading ‘+’ nor exponential notation is recognized. To compare such strings numerically,use the –general-numeric-sort (-g) option.
