如何列出每个单词一次？忽略非字母字符

Question

Unix诞生于1969年，来自贝尔实验室的计算机科学家Ken Thompson。Unix是在一台经过清理的PDP-7小型机上诞生的

 tr -cs "[:alpha:]" "\n" < file | sort -u 

结果看起来不错，但我发现了一个问题，原文中的"PDP-7“变成了"PDP”，我不确定是否应该添加更多的参数？

Answer 1

这似乎符合您的要求(并不是说这是一个格式良好的问题)：

sed -r  's/[[:space:]]/\n/g' unix | sed -r 's/[^a-zA-Z0-9]//g' | sort -u
1960s
1962
1969
a
actual
almost
also
an
and
at
barely
batch
beasts
been
Bell
born
But
by
computer
computing
concept
deployment
earlier
else
everywhere
experience
experimental
first
for
had
him
in
inventor
it
John
Ken
Laboratories
language
late
Lisp
McCarthy
mind
Multics
novel
of
on
one
operating
out
primitive
project
researcher
rule
scientist
seven
speculations
spoiled
still
systems
temperamental
ten
that
the
Thompson
timesharing
Unix
uttered
was
were
which
years

Answer 2

请记住在使用uniq -u之前使用排序，例如：

sort | uniq -u

如果你只想保留字母，你也可以输入以下内容：

sed "s/[[:digit:].-]//g"

希望这能有所帮助。有一个你的代码/列表的例子会很棒。