fmt命令

简单的格式化文本

fmt [option] [file-list]

fmt通过将所有非空白行的长度设置为几乎相同，来进行简单的文本格式化

参数

fmt从file-list中读取文件，并将其内容的格式化版本发送到标准输出。如果不制定文件名或者用连字符（-）来替代文件名，则fmt将从标准输入读取文本信息

选项

-s              截断长行，但不合并

-t               除每个段落的第1行外都缩进

-u              改变格式化，使字之间出现一个空格，句子之间出现两个空格

-w n           将输出的行宽改为n个字符。不带该选项时，fmt输出的行宽度为75个字符

示例

原文件

$ cat demo 
A long time ago, there was a huge apple tree.         A little boy loved to come and play around it every day. He climbed to the tree top, ate the apples, took a nap under the shadow… He loved the tree and the tree loved to play with him. 

fmt -s

$ fmt -s demo 
A long time ago, there was a huge apple tree.         A little boy loved
to come and play around it every day. He climbed to the tree top, ate
the apples, took a nap under the shadow… He loved the tree and the
tree loved to play with him.

截断长行

fmt -t

$ fmt -t demo 
A long time ago, there was a huge apple tree.         A little boy loved
   to come and play around it every day. He climbed to the tree top,
   ate the apples, took a nap under the shadow… He loved the tree and
   the tree loved to play with him.

排除首行的缩进

fmt -u

$ fmt -u demo 
A long time ago, there was a huge apple tree.  A little boy loved to come
and play around it every day. He climbed to the tree top, ate the apples,
took a nap under the shadow… He loved the tree and the tree loved to
play with him.

格式化单词和句子的间隔，很明显A little boy那里的多个空格被截断到两个

fmt -w

$ fmt -w 40 demo 
A long time ago, there was a huge
apple tree.         A little boy
loved to come and play around it
every day. He climbed to the tree top,
ate the apples, took a nap under the
shadow… He loved the tree and the
tree loved to play with him.

指定输出的行宽，这里的行宽为40个字符，我没数过

reference：http://www.cnblogs.com/nerxious/archive/2013/01/09/2853091.html