linux shuf 随机选择器

有些发布版的linux不带shuf命令，shuf命令包含在coreutils这个包里面。

# shuf --helpUsage: shuf [OPTION]... [FILE]  or:  shuf -e [OPTION]... [ARG]...  or:  shuf -i LO-HI [OPTION]...Write a random permutation of the input lines to standard output.Mandatory arguments to long options are mandatory for short options too.  -e, --echo                treat each ARG as an input line  -i, --input-range=LO-HI   treat each number LO through HI as an input line  -n, --head-count=COUNT    output at most COUNT lines  -o, --output=FILE         write result to FILE instead of standard output      --random-source=FILE  get random bytes from FILE  -r, --repeat              output lines can be repeated  -z, --zero-terminated     end lines with 0 byte, not newline      --help     display this help and exit      --version  output version information and exitWith no FILE, or when FILE is -, read standard input.GNU coreutils online help: <http://www.gnu.org/software/coreutils/>For complete documentation, run: info coreutils 'shuf invocation'