[root@master ~]# cat test.txt
firstline
secondline
[root@master ~]# sed 's/^first.*/& zhuijia/' test.txt
firstline zhuijia
secondline
[root@master ~]# sed 's/$/\t1111/' test.txt
firstline 1111
secondline 1111
[root@master ~]# sed '/first/ i\aaaa' test.txt
aaaa
firstline
secondline
[root@master ~]# sed '/first/ a\aaaa' test.txt
firstline
aaaa
secondline
[root@master ~]# sed '/first/ c\aaaa' test.txt
aaaa
secondline