linux系统中如何删除空行

linux系统中如何删除空行。

1、测试数据 a.txt

[root@centos79 test]# ls
a.txt
[root@centos79 test]# cat a.txt
a g r e

i x k like
a f g liker
[root@centos79 test]# cat -A a.txt
a g r e$
$                ## 空行什么也没有
i x k like$
a f g liker$
[root@centos79 test]# sed -n l a.txt
a g r e$
$                    ## 空行什么也没有
i x k like$
a f g liker$

 

2、删除空行

[root@centos79 test]# cat a.txt
a g r e

i x k like
a f g liker
[root@centos79 test]# grep -v "^$" a.txt
a g r e
i x k like
a f g liker
[root@centos79 test]# cat a.txt
a g r e

i x k like
a f g liker
[root@centos79 test]# sed '/^$/d' a.txt
a g r e
i x k like
a f g liker
[root@centos79 test]# cat a.txt
a g r e

i x k like
a f g liker
[root@centos79 test]# awk '/./{print}' a.txt
a g r e
i x k like
a f g liker

继续

[root@centos79 test]# cat a.txt
a g r e

i x k like
a f g liker
[root@centos79 test]# awk NF a.txt
a g r e
i x k like
a f g liker
[root@centos79 test]# cat a.txt
a g r e

i x k like
a f g liker
[root@centos79 test]# sed '/^\s*$/d' a.txt
a g r e
i x k like
a f g liker
[root@centos79 test]# cat a.txt
a g r e

i x k like
a f g liker
[root@centos79 test]# sed '/^[\t ]*$/d' a.txt
a g r e
i x k like
a f g liker

 

3、修改测试文件，在空行中添加空格或者水平制表符

修改后的测试文件：

[root@centos79 test]# ls
a.txt
[root@centos79 test]# cat a.txt

a g r e

i x k like

a f g liker
[root@centos79 test]# cat -A a.txt
$
a g r e$
  $
i x k like$
^I^I$
a f g liker$
[root@centos79 test]# sed -n l a.txt
$
a g r e$
  $
i x k like$
\t\t$
a f g liker$

 

 

4、进行测试

[root@centos79 test]# ls
a.txt
[root@centos79 test]# cat a.txt

a g r e

i x k like

a f g liker
[root@centos79 test]# grep -v "^$" a.txt
a g r e

i x k like

a f g liker
[root@centos79 test]# cat a.txt

a g r e

i x k like

a f g liker
[root@centos79 test]# sed '/^$/d' a.txt
a g r e

i x k like

a f g liker
[root@centos79 test]# cat a.txt

a g r e

i x k like

a f g liker
[root@centos79 test]# awk '/./{print}' a.txt
a g r e

i x k like

a f g liker

继续

[root@centos79 test]#  ls
a.txt
[root@centos79 test]# cat a.txt

a g r e

i x k like

a f g liker
[root@centos79 test]# awk NF a.txt
a g r e
i x k like
a f g liker
[root@centos79 test]# cat a.txt

a g r e

i x k like

a f g liker
[root@centos79 test]# sed '/^\s*$/d' a.txt
a g r e
i x k like
a f g liker
[root@centos79 test]# cat a.txt

a g r e

i x k like

a f g liker
[root@centos79 test]# sed '/^[\t ]*$/d' a.txt
a g r e
i x k like
a f g liker

 

5、补充

[root@centos79 test]# cat a.txt
a g r e

i x k like
a f g liker
[root@centos79 test]# cat -A a.txt
a g r e$
$
i x k like$
a f g liker$
[root@centos79 test]# awk '$0 != ""' a.txt
a g r e
i x k like
a f g liker

 

6、补充

[root@centos79 test]# ls
a.txt
[root@centos79 test]# cat a.txt
a g r e

i x k like
a f g liker
[root@centos79 test]# cat -A a.txt
a g r e$
$
i x k like$
a f g liker$
[root@centos79 test]# cat a.txt |tr -s "\n"
a g r e
i x k like
a f g liker