1、显示/boot/grub/grub.conf中以至少一个空白字符开头的行;
[[email protected] ~]# grep ‘^[[:space:]]\+‘ /boot/grub/grub.conf root (hd0,0) kernel /vmlinuz-2.6.18-128.el5 ro root=LABEL=/ rhgb quiet initrd /initrd-2.6.18-128.el5.img
2、显示/etc/rc.d/rc.sysinit文件中以#开头,后面跟至少一个空白字符,而后又有至少一个非空白字符的行;
[[email protected] ~]# grep ‘^#[[:space:]]\+[^[:space:]]\+‘ /etc/rc.d/rc.sysinit
3、打出netstat -tan命令执行结果中以‘LISTEN’,后或跟空白字符结尾的行;
[[email protected] ~]# netstat -tan | grep ‘LISTEN[[:space:]]*‘ tcp 0 0 127.0.0.1:2208 0.0.0.0:* LISTEN tcp 0 0 0.0.0.0:868 0.0.0.0:* LISTEN tcp 0 0 0.0.0.0:111 0.0.0.0:* LISTEN tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN tcp 0 0 127.0.0.1:2207 0.0.0.0:* LISTEN tcp 0 0 :::22 :::* LISTEN
4、添加用户bash, testbash, basher, nologin (此一个用户的shell为/sbin/nologin),而后找出当前系统上其用户名和默认shell相同的用户的信息;
[[email protected] ~]# useradd bash [[email protected] ~]# useradd testbash [[email protected] ~]# useradd basher [[email protected] ~]# useradd -s /sbin/nologin nologin [[email protected] ~]# grep ‘^\([[:alnum:]]\+\>\).*\1$‘ /etc/passwd sync:x:5:0:sync:/sbin:/bin/sync shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt bash:x:501:501::/home/bash:/bin/bash nologin:x:504:504::/home/nologin:/sbin/nologin
5、显示当前系统上root、fedora或user1用户的默认shell;
[[email protected] ~]# useradd fedora [[email protected] ~]# useradd -s /sbin/nologin user1 [[email protected] ~]# egrep ‘^(root|fedora|user1)‘ /etc/passwd root:x:0:0:root:/root:/bin/bash fedora:x:505:505::/home/fedora:/bin/bash user1:x:506:506::/home/user1:/sbin/nologin
6、找出/etc/rc.d/init.d/functions文件中某单词后面跟一组小括号的行,形如:hello();
[[email protected] ~]# egrep -o ‘^[[:alpha:]]+\(\)‘ /etc/rc.d/init.d/functions
7、使用echo命令输出一个绝对路径,使用grep取出其基名;
[[email protected] ~]# echo /var/www/html/ | egrep -o ‘[^/]+/?$‘ | cut -d/ -f1 html
扩展:取出其路径名
8、找出ifconfig命令结果中的1-255之间数字;
[[email protected] ~]# ifconfig | grep -o ‘\<\([0-1]\?[0-9]\{1,2\}\|2[0-4][0-9]\|25[0-5]\)\>‘| grep -v ‘^0$‘
9、挑战题:写一个模式,能匹配合理的IP地址;
CentOS6.X以前: [[email protected] ~]# ifconfig | grep ‘inet\b‘ | cut -d: -f2 | awk ‘{print $1}‘ | egrep -v ‘^(127|255)‘ 192.168.1.66 CentOS7.x [[email protected] ~]# ifconfig | grep ‘inet\b‘ | awk ‘{print $2}‘ | egrep -v ‘^(127|255)‘ 172.17.0.1 192.168.1.63 192.168.122.1
10、挑战题:写一个模式,能匹配出所有的邮件地址;
[[email protected] ~]# grep -o ‘[[:alnum:]]\[email protected][[:alnum:]]\+\.[[:alnum:]]\+\>‘ mail.sh
11、查找/var目录下属主为root,且属组为mail的所有文件或目录;
[[email protected] ~]# find /var/ -user root -group mail /var/spool/mail
12、查找当前系统上没有属主或属组的文件;
[[email protected] ~]# find / -nouser -o -nogroup
进一步:查找当前系统上没有属主或属组,且最近3天内曾被访问过的文件或目录;
[[email protected] ~]# find / \( -nouser -o -nogroup \) -atime -3
13、查找/etc目录下所有用户都有写权限的文件;
[[email protected] ~]# find /etc -perm -222
14、查找/etc目录下大于1M,且类型为普通文件的所有文件;
[[email protected] ~]# find /etc -size +1M -type f -exec ls -lh {} \; -rw-r--r--. 1 root root 7.8M 3月 17 2015 /etc/selinux/targeted/policy/policy.24 -rw-r--r--. 1 root root 7.8M 3月 17 2015 /etc/selinux/targeted/modules/active/policy.kern -rw-r--r--. 1 root root 2.1M 3月 17 2015 /etc/gconf/gconf.xml.defaults/%gconf-tree.xml
15、查找/etc/init.d/目录下,所有用户都有执行权限,且其它用户有写权限的文件;
[[email protected] ~]# find /etc/init.d/ -perm -113
16、查找/usr目录下不属于root、bin或hadoop的文件;
[[email protected] ~]# find /usr/ -not \( -user root -o -user bin -o -user hadoop \)
17、查找/etc/目录下至少有一类用户没有写权限的文件;
[[email protected] ~]# find /etc -not \( -perm -222 \)
18、查找/etc目录下最近一周内其内容被修改过,且不属于root或hadoop的文件;
[[email protected] ~]# find /etc -mtime -7 -not \( -user root -o -user hadoop \)