保持简单。

grep . filename.txt

从文件中读取行排除空行

grep -v '^$' folderlist.txt

folderlist.txt

folder1/test

folder2
folder3

folder4/backup
folder5/backup

结果如下:

folder1/test
folder2
folder3
folder4/backup
folder5/backup

grep -v "^[[:space:]]*$"

The -v makes it print lines that do not completely match

===Each part explained===
^             match start of line
[[:space:]]   match whitespace- spaces, tabs, carriage returns, etc.
*             previous match (whitespace) may exist from 0 to infinite times
$             match end of line

〇运行代码

$ echo "
> hello
>       
> ok" |
> grep -v "^[[:space:]]*$"
hello
ok

要了解更多关于这是如何/为什么工作的，我建议阅读正则表达式。http://www.regular-expressions.info/tutorial.html

下面是删除白色线条和以#符号开始的线条的另一种方法。我认为这对于读取配置文件非常有用。

[root@localhost ~]# cat /etc/sudoers | egrep -v '^(#|$)'
Defaults    requiretty
Defaults   !visiblepw
Defaults    always_set_home
Defaults    env_reset
Defaults    env_keep =  "COLORS DISPLAY HOSTNAME HISTSIZE INPUTRC KDEDIR
LS_COLORS"
root    ALL=(ALL)       ALL
%wheel  ALL=(ALL)       ALL
stack ALL=(ALL) NOPASSWD: ALL

如果在一行中有多个空行序列，并且每个序列只希望有一个空行，请尝试

grep -v "unwantedThing" foo.txt | cat -s

Cat -s抑制重复的空输出行。

你的输出会从

match1



match2

to

match1

match2

原始输出中的三个空行将被压缩或“压缩”为一个空行。

此代码删除空行和以“#”开头的行

 grep -v "^#" file.txt | grep -v ^[[:space:]]*$