文本过滤、文本查找工具应用示例

文本过滤、文本查找工具应用示例

• 1.显示当前系统上root、fedora或user1用户的默认shell

  [root@localhost ~]# cat /etc/passwd|grep "^root\>\|^fedora\>\|^user1\>"|cut -d: -f7
    /bin/bash
    /bin/bash
    /bin/bash

• 2.找出/etc/rc.d/init.d/functions文件中某个单词后面跟一组小括号的行，形如：hello()

  [root@localhost ~]# cat /etc/rc.d/init.d/functions|grep -o "[[:alpha:]]\+\>()"
   checkpid()
   checkpids()
   kill()
   run()
   pidof()
   daemon()
   killproc()
   pidfileofproc()
   pidofproc()
   status()
   success()
   failure()
   passed()
   warning()
   stage()
   success()
   failure()
   passed()
   warning()
   action()
   strstr()
   file()
   true()
   false()
   sysctl()

• 3.使用echo命令输出一个绝对路径，使用grep取出其基名;扩展,取出其路径名

  [root@localhost ~]# echo "/etc/rc.d/init.d/functions"|grep -o  "[^\/]\+\/\?$"
   functions
  [root@localhost ~]# echo "/etc/rc.d/init.d/functions"|grep -o  "^\/[^[:space:]]\+\/"
   /etc/rc.d/init.d/

• 4.找出ifconfig命令结果中1-255之间的数字

  [root@localhost ~]# ifconfig|grep  -E  -o "([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])"
  33
  41
  63
  150
  192
  168
  91
  128
  255
  255
  255
  192
  168
  91
  255
  6
  80

• 5.挑战题：写一个模式，能匹配合理的IP地址

  [root@localhost ~]# ifconfig|grep  -E  -o "([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])"
   192.168.91.128
   192.168.91.255
   192.168.122.1
   192.168.122.255

• 6.挑战题：写一个模式，能匹配所有的邮件地址

  [root@localhost ~]# echo "[email protected]"|grep -o "[[:alnum:]]\+@[[:alnum:]]\+\.[[:alpha:]]\+"
   [email protected]

• 7.查找/var目录下属主为root，且属组为mail的所有文件或目录

  [root@localhost ~]# find /var -user root -a -group mail -ls
   67292968    0 drwxrwxr-x   2 root     mail          129 Jul 28 18:28 /var/spool/mail

• 8.查找当前系统上没有属主或属组的文件;进一步查找当前系统上没有属主或属组，且最近3天内曾经被访问过的文件或目录

  [root@localhost ~]# find / -nouser  -a -nogroup  -ls
  [root@localhost ~]# find / -nouser  -a -nogroup -a -atime -3  -ls

• 9.查找/etc目录下所有用户都有写权限的文件

  [root@localhost ~]# find /etc -perm -222 -ls
   33554500    0 lrwxrwxrwx   1 root     root           17 Jun 30 01:53 /etc/mtab -> /proc/self/mounts
   35553953    0 lrwxrwxrwx   1 root     root           56 Jun 30 02:10 /etc/fonts/conf.d/65-0-lohit-marathi.conf -> /usr/share/fontconfig/conf.avail/65-0-lohit-marathi.conf
   33722185    0 lrwxrwxrwx   1 root     root           56 Jun 30 01:57 /etc/fonts/conf.d/59-liberation-mono.conf -> /usr/share/fontconfig/conf.avail/59-liberation-mono.conf
   35553954    0 lrwxrwxrwx   1 root     root           59 Jun 30 02:10 /etc/fonts/conf.d/65-0-lohit-devanagari.conf -> /usr/share/fontconfig/conf.avail/65-0-lohit-devanagari.conf
   33722192    0 lrwxrwxrwx   1 root     root           56 Jun 30 01:57 /etc/fonts/conf.d/59-liberation-sans.conf -> /usr/share/fontconfig/conf.avail/59-liberation-sans.conf
   35553957    0 lrwxrwxrwx   1 root     root           54 Jun 30 02:11 /etc/fonts/conf.d/66-ucs-miscfixed.conf -> /usr/share/fontconfig/conf.avail/66-ucs-miscfixed.conf
   33735545    0 lrwxrwxrwx   1 root     root           59 Jun 30 01:57 /etc/fonts/conf.d/10-scale-bitmap-fonts.conf -> /usr/share/fontconfig/conf.avail/10-scale-bitmap-fonts.conf
   35553958    0 lrwxrwxrwx   1 root     root           50 Jun 30 02:11 /etc/fonts/conf.d/60-open-sans.conf -> /usr/share/fontconfig/conf.avail/60-open-sans.conf

• 10.查找/etc目录下大于1M，且类型为普通文件的所有文件

  [root@localhost ~]# find /etc -size +1M -a -type f -ls
   102108754 1364 -rw-r--r--   1 root     root      1394978 Jul  9 05:37 /etc/selinux/targeted/contexts/files/file_contexts.bin
   68163210 3620 -rw-r--r--   1 root     root      3703887 Jul  9 05:37 /etc/selinux/targeted/policy/policy.30
   68163206 3620 -rw-r--r--   1 root     root      3703887 Jul  9 05:37 /etc/selinux/targeted/active/policy.kern
   68112876 7120 -r--r--r--   1 root     root      7289802 Jul  9 05:33 /etc/udev/hwdb.bin
   34410868 1336 -rw-r--r--   1 root     root      1367395 Nov  5  2016 /etc/brltty/zh-tw.ctb