1、查找/etc目录下大于1M且类型为普通文件的所有文件

[root@centos7 ~]#find /etc/ -type f -size +1M 
/etc/udev/hwdb.bin
/etc/selinux/targeted/contexts/files/file_contexts.bin
/etc/selinux/targeted/policy/policy.31
/etc/selinux/targeted/active/policy.kern
/etc/selinux/targeted/active/policy.linked
/etc/brltty/zh-tw.ctb

2、打包/etc/目录下面所有conf结尾的文件，压缩包名称为当天的时间，并拷贝到/usr/local/src目录备份

打包压缩

[root@centos7 ~]#find /etc/ -name "*.conf" | xargs tar -cvf /usr/local/src/`date +%Y-%m-%d`.tar
.......
.......
/etc/sane.d/u12.conf
/etc/sane.d/umax.conf
/etc/dleyna-server-service.conf

查看文件

[root@centos7 ~]#ls /usr/local/src/
2020-03-04.tar

查看包中详细文件

[root@centos7 ~]#tar -t -f /usr/local/src/2020-03-04.tar 
etc/resolv.conf
etc/fonts/conf.d/31-cantarell.conf
etc/fonts/conf.d/66-sil-nuosu.conf
etc/fonts/conf.d/59-liberation-sans.conf
etc/fonts/conf.d/65-0-nhn-nanum-gothic.conf
etc/fonts/conf.d/20-unhint-small-dejavu-sans.conf
......

3、利用sed取出ifconfig命令中本机的IPv4地址

[root@centos7 ~]#ifconfig ens33 | sed -nr '2s/^[^0-9]+([0-9.]+).*$/\1/p'
192.168.44.77

4、删除/etc/fstab文件中所有以#开头，后面至少跟一个空白字符的行的行首的#和空白字符

原始文件

[root@centos7 ~]#cat /etc/fstab 

#
# /etc/fstab
# Created by anaconda on Thu Feb 20 15:16:44 2020
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
UUID=a9562567-8e42-49df-b669-dc9fcfbb872b /                       xfs     defaults        0 0
UUID=350ea448-c558-470c-a4f1-a04016e3addf /boot                   xfs     defaults        0 0
UUID=ce02fe68-d676-4f58-a154-c15ef60f7b5d /data                   xfs     defaults        0 0
UUID=d977663b-f82b-4b57-8f3f-e4b59a784e39 swap                    swap    defaults        0 0

处理后

[root@centos7 ~]#sed  -r -e's/^#[[:space:]]+(.*)$/\1/g'  /etc/fstab | grep -Ev "#"

/etc/fstab
Created by anaconda on Thu Feb 20 15:16:44 2020
Accessible filesystems, by reference, are maintained under '/dev/disk'
See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
UUID=a9562567-8e42-49df-b669-dc9fcfbb872b /                       xfs     defaults        0 0
UUID=350ea448-c558-470c-a4f1-a04016e3addf /boot                   xfs     defaults        0 0
UUID=ce02fe68-d676-4f58-a154-c15ef60f7b5d /data                   xfs     defaults        0 0
UUID=d977663b-f82b-4b57-8f3f-e4b59a784e39 swap                    swap    defaults        0 0

5、处理/etc/fstab路径,使用sed命令取出其目录名和基名

取出目录名

[root@centos7 ~]#echo /etc/fstab | sed -nr 's/^(\/.*\/)([^\/]+)$/\1/p'
/etc/

取出基名

[root@centos7 ~]#echo /etc/fstab | sed -nr 's/^(\/.*\/)([^\/]+)$/\2/p'
fstab