用sed 给文本文件加行号

看例子：

[root@localhost tmp]# sed '=' test.txt
1
tsttst tsttsttst
2
west gao
3
west abces
[root@localhost tmp]# sed = test.txt | sed 'N;s/\n/\t/'
1       tsttst tsttsttst
2       west gao
3       west abces
[root@localhost tmp]# 

N的解释：

N：Add a newline to the pattern space, then append the next line of input to the pattern space. If there is no more input then sed exits without processing any more commands.