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.