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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  ifup		ifup-eth   ifup-isdn   ifup-post    ifup-sit	   init.ipv6-global   network-functions-ipv6
    ifcfg-eth1  ifdown	 ifdown-ippp  ifdown-post  ifdown-sit	  ifup-aliases	ifup-ippp  ifup-plip   ifup-ppp     ifup-tunnel    net.hotplug
    ifcfg-eth2  ifdown-bnep  ifdown-ipv6  ifdown-ppp   ifdown-tunnel  ifup-bnep	ifup-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


分析图解:

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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

  4. 在JBoss框架下严格使用JNDI或其他公共方式进行连接,避免在JAVA程序中通过直接调用getConnection方式进行数据库连接;
    [root@edbnode1 ~]# /bin/find /enterprisedb_backup/postgresql/ -maxdepth 1 -mtime +7 -exec /bin/rm -rf {} \;

解决结果【完成】