Usage: sort [OPTION]... [FILE]...

Write sorted concatenation of all FILE(s) to standard output.

Mandatory arguments to long options are mandatory for short options too.

Ordering options:

  -b, --ignore-leading-blanks  ignore leading blanks

  -d, --dictionary-order      consider only blanks and alphanumeric characters

  -f, --ignore-case           fold lower case to upper case characters

  -g, --general-numeric-sort  compare according to general numerical value

  -i, --ignore-nonprinting    consider only printable characters

  -M, --month-sort            compare (unknown) < `JAN' < ... < `DEC'

  -n, --numeric-sort          compare according to string numerical value

  -r, --reverse               reverse the result of comparisons

Other options:

  -c, --check               check whether input is sorted; do not sort

  -k, --key=POS1[,POS2]     start a key at POS1, end it at POS2 (origin 1)

  -m, --merge               merge already sorted files; do not sort

  -o, --output=FILE         write result to FILE instead of standard output

  -s, --stable              stabilize sort by disabling last-resort comparison

  -S, --buffer-size=SIZE    use SIZE for main memory buffer

  -t, --field-separator=SEP  use SEP instead of non-blank to blank transition

  -T, --temporary-directory=DIR  use DIR for temporaries, not $TMPDIR or /tmp;

                              multiple options specify multiple directories

  -u, --unique              with -c, check for strict ordering;

                              without -c, output only the first of an equal run

  -z, --zero-terminated     end lines with 0 byte, not newline

      --help     display this help and exit

      --version  output version information and exit

-t 定义每个域的分隔符，但如果分隔符是特殊符号，例如tab符，soh，这些十六进制的符号，需要加上$

例如：-t$'\t'或-t$'\x01'

-k 定义选取哪个域进行排序，从1开始，后面可以使用逗号连接第二排序域，例如

-k1,2,3