13. 2、删除第一行 [root@PC3 test]# sed 1d a.txt 2 Beijing 2004 3 Beijing 2005 4 Beijing 2006 5 Beijing 2007 6 Beijing 2008 7 Beijing 2007 8 Beijing 2005 9 Beijing 2006 10 Beijing 2007 11 Beijing 2008 12 Beijing 2007 [root@PC3 test]# tail -n +2 a.txt 2 Beijing 2004 3 Beijin...