浅谈Linux下通过find命令进行rm文件删除的小技巧

我们经常会通过find命令进行批量操作，如：批量删除旧文件、批量修改、基于时间的文件统计、基于文件大小的文件统计等，在这些操作当中，由于rm删除操作会导致目录结构变化，如果要通过find结合rm的操作写成脚本，就会遇到一些麻烦，本文通过一个例子为大家进行介绍。

系统环境：

SUSE Linux Enterprise Server 11 或

Red Hat Enterprise Linux

问题症状：

客户现场有一个自动化的脚本，有以下的find语句，每天运行以删除某个目录下7天以前的文件或目录，这些目录都是按时间顺序生成PostgreSQL数据库的WAL日志及其错误日志pg_log：

/bin/find /enterprisedb_backup/postgresql/ -mtime +7 -exec /bin/rm -rf '{}' \;

运行过程中，间歇性地出现以下错误：

[root@edb ~]# /bin/find /enterprisedb_backup/postgresql/ -mtime +7 -exec /bin/rm -rf {} \;
/bin/find: `/enterprisedb_backup/postgresql/network-scripts': No such file or directory
[root@edb ~]# echo $?
1

显然，以上命令返回了错误的结果，但客户反映说，以上脚本运行后目录下7天前的数据的确备删除了。

问题分析：

进行故障重现，在另一台服务器中通过模拟数据单独运行find命令分析此问题，测试过程如下：

1.模拟数据

[root@edbnode1 ~]# date
Wed Jun 18 23:08:18 CST 2014

[root@edbnode1 ~]# cp -rcp /etc/sysconfig/network-scripts/ /enterprisedb_backup/postgresql/
[root@edbnode1 ~]# cp -rcp /etc/init.d/iptables /enterprisedb_backup/postgresql/## 以上通过 cp -rcp 命令使得拷贝到目标目录的数据保持包括：建立时间、用户权根等信息，以模拟出一个旧文件及一个旧目录

[root@edbnode1 ~]# ll /enterprisedb_backup/postgresql/
total 16
-rwxr-xr-x. 1 root root 9409 Oct 31 2012 iptables
drwxr-xr-x. 2 root root 4096 Jun 18 2013 network-scripts## 以上可以看到iptables文件是2012年建立的，network-scripts是2013年建立的，都远远超过了7天

[root@edbnode1 ~]# ll /enterprisedb_backup/postgresql/*
-rwxr-xr-x. 1 root root 9409 Oct 31 2012 /enterprisedb_backup/postgresql/iptables

/enterprisedb_backup/postgresql/network-scripts:
total 212
-rw-r--r--. 1 root root  159 Jun 18 2013 ifcfg-eth0
-rw-r--r--. 1 root root  203 Jun 18 2013 ifcfg-eth1
-rw-r--r--. 1 root root  203 Jun 18 2013 ifcfg-eth2
-rw-r--r--. 1 root root  254 Jan 9 2013 ifcfg-lo
lrwxrwxrwx. 1 root root  20 Jun 18 2013 ifdown -> ../../../sbin/ifdown
-rwxr-xr-x. 1 root root  627 Jan 9 2013 ifdown-bnep
-rwxr-xr-x. 1 root root 5397 Jan 9 2013 ifdown-eth
-rwxr-xr-x. 1 root root  781 Jan 9 2013 ifdown-ippp
-rwxr-xr-x. 1 root root 4168 Jan 9 2013 ifdown-ipv6
lrwxrwxrwx. 1 root root  11 Jun 18 2013 ifdown-isdn -> ifdown-ippp
-rwxr-xr-x. 1 root root 1481 Jan 9 2013 ifdown-post
-rwxr-xr-x. 1 root root 1064 Jan 9 2013 ifdown-ppp
-rwxr-xr-x. 1 root root  835 Jan 9 2013 ifdown-routes
-rwxr-xr-x. 1 root root 1370 Jan 9 2013 ifdown-sit
-rwxr-xr-x. 1 root root 1434 Jan 9 2013 ifdown-tunnel
lrwxrwxrwx. 1 root root  18 Jun 18 2013 ifup -> ../../../sbin/ifup
-rwxr-xr-x. 1 root root 12365 Jan 9 2013 ifup-aliases
-rwxr-xr-x. 1 root root  859 Jan 9 2013 ifup-bnep
-rwxr-xr-x. 1 root root 10157 Jan 9 2013 ifup-eth
-rwxr-xr-x. 1 root root 11971 Jan 9 2013 ifup-ippp
-rwxr-xr-x. 1 root root 10401 Jan 9 2013 ifup-ipv6
lrwxrwxrwx. 1 root root   9 Jun 18 2013 ifup-isdn -> ifup-ippp
-rwxr-xr-x. 1 root root  727 Jan 9 2013 ifup-plip
-rwxr-xr-x. 1 root root  954 Jan 9 2013 ifup-plusb
-rwxr-xr-x. 1 root root 2364 Jan 9 2013 ifup-post
-rwxr-xr-x. 1 root root 4154 Jan 9 2013 ifup-ppp
-rwxr-xr-x. 1 root root 1925 Jan 9 2013 ifup-routes
-rwxr-xr-x. 1 root root 3499 Jan 9 2013 ifup-sit
-rwxr-xr-x. 1 root root 2488 Jan 9 2013 ifup-tunnel
-rwxr-xr-x. 1 root root 3770 Jan 9 2013 ifup-wireless
-rwxr-xr-x. 1 root root 4623 Jan 9 2013 init.ipv6-global
-rwxr-xr-x. 1 root root 1125 Jan 9 2013 net.hotplug
-rw-r--r--. 1 root root 13079 Jan 9 2013 network-functions
-rw-r--r--. 1 root root 29853 Jan 9 2013 network-functions-ipv6
## 以上可以看到network-script不是一个空的目录，当中还有文件，而且文件也都已经是7天前建立的了

2.测试单独模拟执行脚本中的find + rm指令

[root@edbnode1 ~]# /bin/find /enterprisedb_backup/postgresql/ -mtime +7 -exec /bin/rm -rf {} \;
/bin/find: `/enterprisedb_backup/postgresql/network-scripts': No such file or directory
[root@edbnode1 ~]# echo $?
1
[root@edbnode1 ~]# ls /enterprisedb_backup/postgresql/
[root@edbnode1 ~]#

可以看到find操作的确返回了错误的结果，但查看数据备份目录发现，iptables文件及network-scripts目录已经正确删除

3.由于数据已经正确删除，因此我们开始怀疑是由network-scripts目录删除后，find继续尝试删除此目录下其它文件，导致出不“No such file or directory”的错误，因此需要于进一步证实此猜想，重新执行以上“第1步”中的数据环境模拟，并执行以下操作，主要是将rm转换成ls以展现整体运行过程：

[root@edbnode1 ~]# cp -rcp /etc/sysconfig/network-scripts/ /enterprisedb_backup/postgresql/
[root@edbnode1 ~]# cp -rcp /etc/init.d/iptables /enterprisedb_backup/postgresql/
[root@edbnode1 ~]# /bin/find /enterprisedb_backup/postgresql/ -mtime +7 -exec /bin/ls {} \;
ifcfg-eth0 ifcfg-lo ifdown-eth  ifdown-isdn ifdown-routes ifupifup-eth  ifup-isdn  ifup-post  ifup-sit  init.ipv6-global  network-functions-ipv6
ifcfg-eth1 ifdown ifdown-ippp ifdown-post ifdown-sit ifup-aliasesifup-ippp ifup-plip  ifup-ppp   ifup-tunnel  net.hotplug
ifcfg-eth2 ifdown-bnep ifdown-ipv6 ifdown-ppp  ifdown-tunnel ifup-bnepifup-ipv6 ifup-plusb ifup-routes ifup-wireless network-functions
/enterprisedb_backup/postgresql/network-scripts/ifup-plusb
/enterprisedb_backup/postgresql/network-scripts/ifup-sit
/enterprisedb_backup/postgresql/network-scripts/ifdown-post
/enterprisedb_backup/postgresql/network-scripts/ifcfg-lo
/enterprisedb_backup/postgresql/network-scripts/network-functions
/enterprisedb_backup/postgresql/network-scripts/ifup-bnep
/enterprisedb_backup/postgresql/network-scripts/ifup-ippp
/enterprisedb_backup/postgresql/network-scripts/ifdown-sit
/enterprisedb_backup/postgresql/network-scripts/ifdown-tunnel
/enterprisedb_backup/postgresql/network-scripts/ifup-plip
/enterprisedb_backup/postgresql/network-scripts/ifup-eth
/enterprisedb_backup/postgresql/network-scripts/ifdown-ipv6
/enterprisedb_backup/postgresql/network-scripts/ifdown-ippp
/enterprisedb_backup/postgresql/network-scripts/ifup-aliases
/enterprisedb_backup/postgresql/network-scripts/network-functions-ipv6
/enterprisedb_backup/postgresql/network-scripts/ifup-ipv6
/enterprisedb_backup/postgresql/network-scripts/ifup-post
/enterprisedb_backup/postgresql/network-scripts/ifcfg-eth2
/enterprisedb_backup/postgresql/network-scripts/ifcfg-eth1
/enterprisedb_backup/postgresql/network-scripts/ifdown-ppp
/enterprisedb_backup/postgresql/network-scripts/ifup-isdn
/enterprisedb_backup/postgresql/network-scripts/ifcfg-eth0
/enterprisedb_backup/postgresql/network-scripts/ifdown
/enterprisedb_backup/postgresql/network-scripts/ifup-wireless
/enterprisedb_backup/postgresql/network-scripts/ifup-ppp
/enterprisedb_backup/postgresql/network-scripts/ifdown-eth
/enterprisedb_backup/postgresql/network-scripts/init.ipv6-global
/enterprisedb_backup/postgresql/network-scripts/ifdown-isdn
/enterprisedb_backup/postgresql/network-scripts/ifup-tunnel
/enterprisedb_backup/postgresql/network-scripts/ifdown-routes
/enterprisedb_backup/postgresql/network-scripts/ifdown-bnep
/enterprisedb_backup/postgresql/network-scripts/net.hotplug
/enterprisedb_backup/postgresql/network-scripts/ifup
/enterprisedb_backup/postgresql/network-scripts/ifup-routes
/enterprisedb_backup/postgresql/iptables

通过以上操作我们可以看到，find命令不单查询了/enterprisedb_backup/postgresql/目录，并且遍历了所有子目录，因此支持了我们的推断

4.综上所述基本定位问题所在

解决方案：

1.整理思路后，可以确认，如果find只找出所需操作目录的第1层文件及目录即可解决此问题

2.通过伟大的 man 命令我们得到以下信息

-maxdepth levels
 Descend at most levels (a non-negative integer) levels of directories below the command line arguments. -maxdepth 0 means only apply the tests and actions to the command line arguments.

3.测试操作确认修改为：

[root@edbnode1 ~]# /bin/find /enterprisedb_backup/postgresql/ -mtime +7 -maxdepth 1 -exec /bin/rm -rf {} \;
/bin/find: warning: you have specified the -maxdepth option after a non-option argument -mtime, but options are not positional (-maxdepth affects tests specified before it as well as those specified after it). Please specify options before other arguments.

这里意思是说：-mtime找到的信息可能会操过-maxdepth的范围，在find操作中建议-maxdepth放在所有其他参数的前面

解决结果【完成】