1、在最后一行加：

sed -i '$a\Defaults logfile=/var/log/sudo.log' /etc/sudoers

2、替换字符：

sed -i 's/Allow from .example.com/Allow from localhost/g' /usr/local/xxx/config/apache/extra/httpd-info.conf

3、在匹配行下方几行开始加：

sed -i -e '/location ~ \/\\.ht/{n;n;s|$|\n #-------------------------------------------------|}' /usr/local/xxx/config/nginx/vhost/default.conf
sed -i -e '/location ~ \/\\.ht/{n;n;n;s|$|\n location /nginx-status {|}' /usr/local/xxx/config/nginx/vhost/default.conf
sed -i -e '/location ~ \/\\.ht/{n;n;n;n;s|$|\n stub_status on;|}' /usr/local/xxx/config/nginx/vhost/default.conf
sed -i -e '/location ~ \/\\.ht/{n;n;n;n;n;s|$|\n access_log off;|}' /usr/local/xxx/config/nginx/vhost/default.conf
sed -i -e '/location ~ \/\\.ht/{n;n;n;n;n;n;s|$|\n }|}' /usr/local/xxx/config/nginx/vhost/default.conf

4、删除匹配性开头的行：

sed -i '/^Defaults logfile=\/var\/log\/sudo.log.*/d' /etc/sudoers

5、删除匹配行，并且删除前一行，后三行：

sed -i '/location \/nginx-status/,+3d;:go;1,1!{P;$!N;D};N;bgo' /usr/local/xxx/config/nginx/vhost/default.conf

6、利用字符串匹配取区间

本题可以取以"device"开头以 "}"结尾，然后将里面的符合要求的字符串过滤计数就可以了。
取区间的方法：
sed -n '/^device/,/\}$/p' oldboy.log
awk '/device: {/, /}/' oldboy.log
提示：
sed -n '/区间开始标识/,/区间结束标识/p' oldboy.log

7、从多少行到多少行

sed -n '16214,24400p' default.err >mysqlerr.log

8、将\n换行符替换成空格（sed高级应用很重要）

[root@localhost ~]# chkconfig --list | grep xyz| awk '{print $1}' | sed 's/\/n/ /g'
xyz_apache
xyz_app
xyz_clamd
xyz_ctasd_in
xyz_ctasd_out
xyz_dovecot
xyz_dspam
xyz_mysqld
xyz_nginx
xyz_openldap
xyz_postfix
xyz_postgresql
xyz_postgrey
xyz_redis
xyz_spamassassin方法1：
[root@localhost ~]# chkconfig --list | grep umail| awk '{print $1}' | sed ':a;N;s/\n/ /g;ta'
xyz_apache xyz_app xyz_clamd xyz_ctasd_in xyz_ctasd_out xyz_dovecot xyz_dspam xyz_mysqld xyz_nginx xyz_openldap xyz_postfix xyz_postgresql xyz_postgrey xyz_redis xyz_spamassassin方法2：
[root@localhost ~]# chkconfig --list | grep umail| awk '{print $1}' | tr "\n" " "
xyz_apache xyz_app xyz_clamd xyz_ctasd_in xyz_ctasd_out xyz_dovecot xyz_dspam xyz_mysqld xyz_nginx xyz_openldap xyz_postfix xyz_postgresql xyz_postgrey xyz_redis xyz_spamassassin命令扩展：
[root@localhost~]# for i in `chkconfig --list | grep xyz| awk '{print $1}' | sed ':a;N;s/\n/ /g;ta'`; do /etc/init.d/$i status; done

9、删除空行

sed '/^$/d'