保留最新N份备份目录脚本

如下所示，在/opt/backup下是备份目录，只需要保留最新的三份备份，在此之前的备份目录都要删除。

[root@syslog-ng ~]# cd /opt/backup/
[root@syslog-ng backup]# ls -l
total 68
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180626
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180627
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180628
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180629
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180630
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180631
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180701
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180702
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180703
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180704
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180705
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180706
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180707
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180708
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180709
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180710
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180711

[root@syslog-ng backup]# /bin/ls -l |grep "^d"
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180626
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180627
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180628
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180629
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180630
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180631
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180701
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180702
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180703
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180704
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180705
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180706
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180707
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180708
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180709
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180710
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180711

[root@syslog-ng backup]# /bin/ls -l |grep "^d"|awk '{print $9}'
20180626
20180627
20180628
20180629
20180630
20180631
20180701
20180702
20180703
20180704
20180705
20180706
20180707
20180708
20180709
20180710
20180711

[root@syslog-ng backup]# /bin/ls -l |grep "^d"|awk '{print $9}'|wc -l
17
[root@syslog-ng backup]# /usr/bin/expr 17 - 3
14

处理脚本如下

[root@syslog-ng backup]# cat /opt/del.sh
#!/bin/bash
cd /opt/backup
NUM1=$(/bin/ls -l |grep "^d"|awk '{print $9}'|wc -l)
NUM2=$(/usr/bin/expr $NUM1 - 3)
/bin/ls -l |grep "^d"|awk '{print $9}'|/bin/sed -n "1,$NUM2 p"|xargs rm -rf

授予脚本执行权限

[root@syslog-ng backup]# chmod 755 /opt/del.sh

执行脚本

[root@syslog-ng backup]# sh /opt/del.sh

执行脚本后，发现保留下来的备份目录就行最新的三份了

[root@syslog-ng backup]# ll
total 12
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180709
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180710
drwxr-xr-x. 2 root root 4096 Jul 11 14:48 20180711