shuf命令简单用法

shuf命令简单用法

背景：需要将一个文件的内容按照行进行打乱顺序；需要从一个大文件中随机获取多少行的内容，除了python脚本处理以外，一些shell命令也可以更快捷的做到

shuf命令详解

bash-4.1$ shuf --help
Usage: 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
  -z, --zero-terminated     end lines with 0 byte, not newline
      --help     display this help and exit
      --version  output version information and exit

With no FILE, or when FILE is -, read standard input.

Report shuf bugs to bug-coreutils@gnu.org
GNU coreutils home page: <http://www.gnu.org/software/coreutils/>
General help using GNU software: <http://www.gnu.org/gethelp/>
For complete documentation, run: info coreutils 'shuf invocation'

# 例1：将一个文件顺序打乱输出到另一个文件
shuf a.txt > b.txt
shuf a.txt -o b.txt  # 以文件格式输出到b

# 例2：将一个文件中的数据随机获取50条数据存到另一个文件中
shuf a.txt -o b.txt -n 30