1、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()；
[root@localhost~]# ls /etc/rc.d/init.d/
functions netconsole network README
[root@localhost ~]# grep -o "\<.*\>()"/etc/rc.d/init.d/functions
checkpid()
__pids_var_run()
__pids_pidof()
daemon()
killproc()
pidfileofproc()
pidofproc()
status()
echo_success()
echo_failure()
echo_passed()
echo_warning()
update_boot_stage()
success()
failure()
passed()
warning()
action()
strstr()
2、使用echo命令输出一个绝对路径，使用grep取出其基名；
[root@localhost~]# echo "/etc/rc.d/init.d/functions"| grep -E -o "[^/]+$"
functions
扩展：取出其路径名
[root@localhost~]# echo "/etc/rc.d/init.d/functions" | grep -E -o "^/.*/"
/etc/rc.d/init.d/
3、找出ifconfig命令结果中的1-255之间数字；
[root@localhost ~]# ifconfig
eno16777736: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.2.108 netmask255.255.255.0 broadcast 192.168.2.255
inet6 fe80::20c:29ff:fe0d:4a8b prefixlen 64 scopeid0x20<link>
ether 00:0c:29:0d:4a:8b txqueuelen 1000 (Ethernet)
RX packets 419 bytes 41325 (40.3KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 337 bytes 46637 (45.5KiB)
TX errors 0 dropped 0 overruns0 carrier 0 collisions 0
lo:flags=73<UP,LOOPBACK,RUNNING> mtu65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 0 (Local Loopback)
RX packets 4 bytes 340 (340.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 4 bytes 340 (340.0 B)
TX errors 0 dropped 0 overruns0 carrier 0 collisions 0
virbr0:flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 192.168.122.1 netmask255.255.255.0 broadcast 192.168.122.255
ether 52:54:00:47:81:6c txqueuelen 0 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns0 carrier 0 collisions 0
[root@localhost ~]#ifconfig | grep -E -o "\<([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\>"
192
168
2
108
255
255
255
0
192
168
2
255
64
29
38
5
0
0
0
0
40
8
0
0
0
0
0
73
127
0
0
1
255
0
0
0
1
128
0
4
0
0
0
0
0
4
0
0
0
0
0
0
192
168
122
1
255
255
255
0
192
168
122
255
52
54
47
81
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
4、查找当前系统上没有属主或属组的文件；
[root@localhost~]# find / -nouser -o -nogroup
/home/mandriva
/home/mandriva/.bash_logout
/home/mandriva/.bash_profile
/home/mandriva/.bashrc
/home/mandriva/.mozilla
/home/mandriva/.mozilla/extensions
/home/mandriva/.mozilla/plugins
find: ‘/proc/3244/task/3244/fd/6’: 没有那个文件或目录
find:‘/proc/3244/task/3244/fdinfo/6’: 没有那个文件或目录
find: ‘/proc/3244/fd/6’: 没有那个文件或目录
find:‘/proc/3244/fdinfo/6’: 没有那个文件或目录
/var/spool/mail/mandriva
[root@localhost ~]#
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；
[root@localhost ~]# find / \( -nouser -o-nogroup \) -a -atime -3
/home/mandriva
/home/mandriva/.mozilla
/home/mandriva/.mozilla/extensions
/home/mandriva/.mozilla/plugins
find: ‘/proc/3254/task/3254/fd/6’: 没有那个文件或目录
find: ‘/proc/3254/task/3254/fdinfo/6’: 没有那个文件或目录
find: ‘/proc/3254/fd/6’: 没有那个文件或目录
find: ‘/proc/3254/fdinfo/6’: 没有那个文件或目录
5、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
4239312 6852 -r--r--r-- 1 root root 7014922 12月 11 00:24/etc/udev/hwdb.bin
202385046 3772 -rw-r--r-- 1 root root 3858924 11月 21 2015 /etc/selinux/targeted/policy/policy.29
4083229 1336 -rw-r--r-- 1 root root 1367395 3月 6 2015/etc/brltty/zh-tw.ctb
[root@localhost ~]#
6、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；
[root@localhost ~]# find /etc/init.d/ -perm/113 -ls
201494444 0 drwxr-xr-x 2 root root 66 12月 10 00:22/etc/init.d/
201868855 4 -rwxr-xr-x 1 root root 2989 9月 16 2015 /etc/init.d/netconsole
201868856 8 -rwxr-xr-x 1 root root 6630 9月 16 2015 /etc/init.d/network
7、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；
[root@localhost~]# find /etc/ -not \( -user root -o -user hadoop \) -atime -7 -ls
find: 用户名‘hadoop’ 未知
[root@localhost ~]# find/etc/ -not \( -user root -o -user bin \) -atime -7 -ls
134780546 0 drwx------ 2 polkitd root 63 12月 10 00:21 /etc/polkit-1/rules.d
136093649 0 drwx--x--x 2 sssd sssd 6 8月 3 00:58 /etc/sssd
[root@localhost ~]#
8、复制/etc/rc.d/rc.sysinit文件至/tmp目录，将/tmp/rc.sysinit文件中的以至少一个空白字符开头的行的行首加#；
[root@localhost~]# ls /etc/rc.d/
init.d rc0.d rc1.d rc2.d rc3.d rc4.d rc5.d rc6.d rc.local
[root@localhost ~]#
[root@localhost~]# cp /etc/rc.d/rc.local /tmp/
[root@localhost ~]# ls /tmp/
mytest2 systemd-private-62113d01174b48f3b9b96b264b53cd52-cups.service-x1z7b8
rc.local systemd-private-62113d01174b48f3b9b96b264b53cd52-vmtoolsd.service-pkrcv0
[root@localhost ~]# sed -i 's/\(^[[:space:]]\)/#\1/g' /tmp/rc.local
9、删除/tmp/rc.sysinit文件中的以#开头，且后面跟了至少一个空白字符的行行的#和空白字符
[root@localhost~]# cat /etc/rc.local
#!/bin/bash
# THIS FILE IS ADDED FOR COMPATIBILITY PURPOSES
#
# It is highly advisable to create own systemd services or udev rules
# to run scripts during boot instead of using this file.
#
# In contrast to previous versions due to parallel execution during boot
# this script will NOT be run after all other services.
#
# Please note that you must run 'chmod +x /etc/rc.d/rc.local' to ensure
# that this script will be executed during boot.
touch /var/lock/subsys/local
[root@localhost ~]# cp /etc/rc.d/rc.local /tmp/
[root@localhost ~]# ls /tmp/
mytest2 systemd-private-62113d01174b48f3b9b96b264b53cd52-cups.service-x1z7b8
rc.local systemd-private-62113d01174b48f3b9b96b264b53cd52-vmtoolsd.service-pkrcv0
[root@localhost~]# sed -i 's/^#[[:space:]]\+//g' /tmp/rc.local
[root@localhost ~]# cat /tmp/rc.local
#!/bin/bash
THIS FILE IS ADDED FOR COMPATIBILITY PURPOSES
#
It is highly advisable to create own systemd services or udev rules
to run scripts during boot instead of using this file.
#
In contrast to previous versions due to parallel execution during boot
this script will NOT be run after all other services.
#
Please note that you must run 'chmod +x /etc/rc.d/rc.local' to ensure
that this script will be executed during boot.
touch /var/lock/subsys/local
[root@localhost ~]#
10、将/etc/yum.repos.d/CentOS-Media.repo文件中所有的enabled=0或gpgcheck=0的最后的0修改为1；
[root@localhost~]# sed 's/enabled=0/enabled=1/g;s/gpgcheck=1/gpgcheck=2/g;'/etc/yum.repos.d/CentOS-Media.rep
11、每周2，4，6备份/var/log/messages文件至/backup/messages_logs/目录中，保存的文件名形如messages-20161202
[root@localhost~]# crontab -e
00 00 * *2,4,6 cp -r /var/log/messages /backup/messages_logs/messages-$(date +/%Y/%m/%d)
12、每天每两小时取当前系统/proc/meminfo文件中的所有以S开头的信息至/stats/memory.txt文件中
[root@localhost~]# crontab -e
00 */2 * * *cat /proc/meminfo |grep "^S" >> /stats/memory.txt
13、写一个脚本创建10用户user10-user19；密码同用户名；
[root@localhost~]# vi test02
#!/bin/sh
for i in {10..19};do
id user$i &>/dev/dull
if [ $? -eq 0 ];then
echo "user$i exits"
else
useradd user$i
echo "user$i"| passwd --stdin user$i
echo "user$i added"
fi
done
