一、
1.每天将/etc/目录下所有文件，备份到/data独立的子目录下，并要求子目录格式为backupYYYY-mm-dd，备份过程可见。
[root@centos7 data]# pwd /data [root@centos7 data]# ll total 0 [root@centos7 data]# cp -av /etc/ /data/backup`date +%F` [root@centos7 data]# ll total 12 drwxr-xr-x. 76 root root 8192 Mar 24 11:51 backup2021-03-24
二、
(1)如何创建/testdir/dir1/x，/testdir/dir1/y， /testdir/dir1/x/a， /testdir/dir1/x/b， /testdir/dir1/y/a， /testdir/dir1/y/b
[root@centos7 data]# mkdir -p testdir/dir1/{x,y}/{a,b} [root@centos7 data]# tree testdir/ testdir/ └── dir1 ├── x │ ├── a │ └── b └── y ├── a └── b 7 directories, 0 files
(2)如何创建/testdir/dir2/x, /testdir/dir2/y, /testdir/dir2/x/a, /testdir/dir2/x/b
[root@centos7 data]# mkdir -p testdir/dir2/{x,y} testdir/dir2/x/{a,b}
[root@centos7 data]# mkdir -p testdir/dir2/{x/{a,b},y} [root@centos7 data]# tree testdir/ testdir/ ├── dir1 │ ├── x │ │ ├── a │ │ └── b │ └── y │ ├── a │ └── b └── dir2 ├── x │ ├── a │ └── b └── y 12 directories, 0 files
(3)如何创建/testdir/dir3, /testdir/dir4, /testdir/dir5, /testdir/dir5/dir6, /testdir/dir5/dir7
[root@centos7 data]# mkdir -p testdir/dir{3..5} testdir/dir5/dir{6,7}
[root@centos7 data]# mkdir -p testdir/dir{3,4,5/dir{6,7}} [root@centos7 data]# tree testdir/ testdir/ ├── dir1 │ ├── x │ │ ├── a │ │ └── b │ └── y │ ├── a │ └── b ├── dir2 │ ├── x │ │ ├── a │ │ └── b │ └── y ├── dir3 ├── dir4 └── dir5 ├── dir6 └── dir7 17 directories, 0 files
三、
1、将/etc/issue文件中的内容转换为大写后保存至/tmp/issue.out文件中
[root@centos7 data]# cat /etc/issue S Kernel on an m [root@centos7 data]# cat /etc/issue |tr [a-z] [A-Z] > /tmp/issue.out [root@centos7 data]# cat /tmp/issue.out S KERNEL R ON AN M
2、将当前系统登录用户的信息转换为大写后保存至/tmp/who.out文件中
[root@centos7 data]# who | tr [a-z] [A-Z] > /tmp/who.out [root@centos7 data]# cat /tmp/who.out ROOT TTY1 2021-03-24 11:26 ROOT PTS/2 2021-03-24 14:09 (10.0.0.1) [root@centos7 data]#
3、一个linux用户给root发邮件，要求邮件标题为"help",邮件正文如下:
Hello, l am 用户名,The system version is here,please help me to check it ,thanks!
操作系统版本信息
[wang@centos7 ~]$ id uid=1000(wang) gid=1000(wang) groups=1000(wang) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 [wang@centos7 ~]$ echo Hello, I am `whoami`,The system version is here,please help me to check it ,thanks! `cat /etc/redhat-release` | mail -s 'help' root [wang@centos7 ~]$ #root [root@centos7 data]# mail Heirloom Mail version 12.5 7/5/10. Type ? for help. "/var/spool/mail/root": 4 messages 1 new 2 unread U 1 Mail Delivery Subsys Mon Mar 22 14:31 71/2726 "Returned mail: see transcript for details" 2 Mail Delivery Subsys Mon Mar 22 14:32 71/2727 "Returned mail: see transcript for details" 3 wang@localhost.local Wed Mar 24 14:52 21/774 "help" >N 4 wang@localhost.local Wed Mar 24 14:53 20/875 "help" & 4 Message 4: From wang@localhost.localdomain Wed Mar 24 14:53:07 2021 Return-Path: <wang@localhost.localdomain> From: wang@localhost.localdomain Date: Wed, 24 Mar 2021 14:53:07 +0800 To: root@localhost.localdomain Subject: help User-Agent: Heirloom mailx 12.5 7/5/10 Content-Type: text/plain; charset=us-ascii Status: R Hello, I am wang,The system version is here,please help me to check it ,thanks! CentOS Linux release 7.9.2009 (Core) &
4、将/root/下文件列表，显示成一行，并文件名之间用空格隔开
[root@centos7 data]# ls /root anaconda-ks.cfg a.txt dead.letter mail.rc [root@centos7 data]# ls /root/ | tr " " ' ' anaconda-ks.cfg a.txt dead.letter mail.rc
5、计算1+2+3+..+99+100的总和
[root@centos7 data]# seq -s + 100|bc 5050 [root@centos7 data]#
6、删除Windows文本文件中的回车字符，即“ ”
[root@centos7 data]# file win.txt win.txt: ASCII text, with CRLF line terminators [root@centos7 data]# file linux.txt linux.txt: ASCII text [root@centos7 data]# hexdump -c win.txt 0000000 a s d a s d a s d n k j 0000010 a s d a s d q j i w o e 1 2 0000020 3 3 4 j 9 j a 2 000002a [root@centos7 data]# hexdump -c linux.txt 0000000 a s d a s m s k d l m f l s 0000010 a m s l k d q m w e l 000001d [root@centos7 data]# dos2unix win.txt dos2unix: converting file win.txt to Unix format ... [root@centos7 data]# hexdump -c win.txt 0000000 a s d a s d a s d n k j a s 0000010 d a s d q j i w o e 1 2 3 3 0000020 4 j 9 j a 2 0000026 #方法2 [root@centos7 data]# tr -d " " < win.txt
7、处理字符串“xt,I 1 jr#!$mn2 c*/fe 3 uz4" ,只保留其中的数字和空格
[root@centos7 data]# echo xt,I 1 jr#uz4mn2 c*/fe 3 uz4 | tr -d [[:punct:]][[:alpha:]] 1 42 3 4
8、将PATH变量每个目录显示在独立的一行
[root@centos7 data]# echo $PATH /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin [root@centos7 data]# echo $PATH | tr : \n /usr/local/sbin /usr/local/bin /usr/sbin /usr/bin /root/bin
四、
1.显示/etc目录下所有以l开头，以一个小写字母结尾，且中间出现至少一位数字的文件或目录列表
[root@centos7 data]# ll /etc/l*[[:digit:]]*[[:lower:]]
[root@centos7 data]# find /etc/ -name "l*[[:digit:]]*[[:lower:]]"
/etc/selinux/targeted/active/modules/100/l2tp
2.显示/etc目录下以任意-一位数字开头，且以非数字结尾的文件或目录列表
[root@centos7 data]# ll /etc/[[:digit:]]*[^[:digit:]] [root@centos7 data]# find /etc/ -name "[[:digit:]]*[^[:digit:]]" /etc/grub.d/00_header /etc/grub.d/01_users /etc/grub.d/10_linux /etc/grub.d/20_linux_xen /etc/grub.d/20_ppc_terminfo /etc/grub.d/30_os-prober /etc/grub.d/40_custom /etc/grub.d/41_custom /etc/grub.d/00_tuned /etc/sysctl.d/99-sysctl.conf /etc/profile.d/256term.csh /etc/profile.d/256term.sh /etc/NetworkManager/dispatcher.d/00-netreport /etc/NetworkManager/dispatcher.d/11-dhclient /etc/NetworkManager/dispatcher.d/10-sendmail /etc/X11/xorg.conf.d/00-keyboard.conf /etc/polkit-1/rules.d/50-default.rules /etc/polkit-1/rules.d/49-polkit-pkla-compat.rules /etc/polkit-1/localauthority/10-vendor.d /etc/polkit-1/localauthority/20-org.d /etc/polkit-1/localauthority/30-site.d /etc/polkit-1/localauthority/50-local.d /etc/polkit-1/localauthority/90-mandatory.d /etc/cron.hourly/0anacron /etc/cron.d/0hourly /etc/security/limits.d/20-nproc.conf /etc/kernel/postinst.d/51-dracut-rescue-postinst.sh
3.显示/etc/目录下以非字母开头，后面跟了一个字母及其它任意长度任意字符的文件或目录列表
[root@centos7 data]# find /etc/ -name "[^[:alpha:]][[:alpha:]]*" /etc/skel/.bash_logout /etc/skel/.bash_profile /etc/skel/.bashrc /etc/cron.hourly/0anacron /etc/cron.d/0hourly /etc/selinux/targeted/.policy.sha512 /etc/.pwd.lock /etc/.updated /etc/1abc2.txt2
4.显示/etc/目录下所有以rc开头,并后面是0-6之间的数字，其它为任意字符的文件或目录列表
[root@centos7 data]# find /etc/ -name "rc[0-6]*" /etc/rc.d/rc0.d /etc/rc.d/rc1.d /etc/rc.d/rc2.d /etc/rc.d/rc3.d /etc/rc.d/rc4.d /etc/rc.d/rc5.d /etc/rc.d/rc6.d /etc/rc0.d /etc/rc1.d /etc/rc2.d /etc/rc3.d /etc/rc4.d /etc/rc5.d /etc/rc6.d
5.显示/etc目录下， 所有.conf结尾，且以m,n,rp开头的文件或目录列表
[root@centos7 data]# find /etc/ -name "[mnrp]*.conf" /etc/resolv.conf /etc/dbus-1/system.d/nm-dispatcher.conf /etc/dbus-1/system.d/nm-ifcfg-rh.conf /etc/prelink.conf.d/nss-softokn-prelink.conf /etc/ld.so.conf.d/mariadb-x86_64.conf /etc/nsswitch.conf /etc/security/pwquality.conf /etc/security/namespace.conf /etc/security/pam_env.conf /etc/plymouth/plymouthd.conf /etc/rsyslog.conf /etc/man_db.conf /etc/mke2fs.conf
6.只显示/root下的隐藏文件和目录列表
#方法1 [root@centos7 ~]# l. . .. .bash_history .bash_logout .bash_profile .bashrc .cshrc .lesshst .tcshrc #方法2 [root@centos7 ~]# ls -d .* . .. .bash_history .bash_logout .bash_profile .bashrc .cshrc .lesshst .tcshrc #方法3 [root@centos7 ~]# find /root/ -name ".*" /root/.bash_logout /root/.bash_profile /root/.bashrc /root/.cshrc /root/.tcshrc /root/.bash_history /root/.lesshst
7.只显示/etc下的非隐藏目录列表
[root@centos7 ~]# ls /etc/[^.]*/ -d /etc/alternatives/ /etc/dhcp/ /etc/logrotate.d/ /etc/popt.d/ /etc/rpm/ /etc/systemd/ /etc/audisp/ /etc/dracut.conf.d/ /etc/mail/ /etc/postfix/ /etc/rsyslog.d/ /etc/terminfo/ /etc/audit/ /etc/firewalld/ /etc/modprobe.d/ /etc/ppp/ /etc/rwtab.d/ /etc/tmpfiles.d/ /etc/bash_completion.d/ /etc/gcrypt/ /etc/modules-load.d/ /etc/prelink.conf.d/ /etc/sasl2/ /etc/tuned/ /etc/binfmt.d/ /etc/gnupg/ /etc/my.cnf.d/ /etc/profile.d/ /etc/security/ /etc/udev/ /etc/chkconfig.d/ /etc/groff/ /etc/NetworkManager/ /etc/python/ /etc/selinux/ /etc/vmware-tools/ /etc/cron.d/ /etc/grub.d/ /etc/openldap/ /etc/rc0.d/ /etc/skel/ /etc/wpa_supplicant/ /etc/cron.daily/ /etc/gss/ /etc/opt/ /etc/rc1.d/ /etc/smrsh/ /etc/X11/ /etc/cron.hourly/ /etc/init.d/ /etc/pam.d/ /etc/rc2.d/ /etc/ssh/ /etc/xdg/ /etc/cron.monthly/ /etc/iproute2/ /etc/pkcs11/ /etc/rc3.d/ /etc/ssl/ /etc/xinetd.d/ /etc/cron.weekly/ /etc/kernel/ /etc/pki/ /etc/rc4.d/ /etc/statetab.d/ /etc/yum/ /etc/dbus-1/ /etc/krb5.conf.d/ /etc/plymouth/ /etc/rc5.d/ /etc/sudoers.d/ /etc/yum.repos.d/ /etc/default/ /etc/ld.so.conf.d/ /etc/pm/ /etc/rc6.d/ /etc/sysconfig/ /etc/depmod.d/ /etc/libnl/ /etc/polkit-1/ /etc/rc.d/ /etc/sysctl.d/ [root@centos7 ~]# ls -d /etc/*/ /etc/alternatives/ /etc/dhcp/ /etc/logrotate.d/ /etc/popt.d/ /etc/rpm/ /etc/systemd/ /etc/audisp/ /etc/dracut.conf.d/ /etc/mail/ /etc/postfix/ /etc/rsyslog.d/ /etc/terminfo/ /etc/audit/ /etc/firewalld/ /etc/modprobe.d/ /etc/ppp/ /etc/rwtab.d/ /etc/tmpfiles.d/ /etc/bash_completion.d/ /etc/gcrypt/ /etc/modules-load.d/ /etc/prelink.conf.d/ /etc/sasl2/ /etc/tuned/ /etc/binfmt.d/ /etc/gnupg/ /etc/my.cnf.d/ /etc/profile.d/ /etc/security/ /etc/udev/ /etc/chkconfig.d/ /etc/groff/ /etc/NetworkManager/ /etc/python/ /etc/selinux/ /etc/vmware-tools/ /etc/cron.d/ /etc/grub.d/ /etc/openldap/ /etc/rc0.d/ /etc/skel/ /etc/wpa_supplicant/ /etc/cron.daily/ /etc/gss/ /etc/opt/ /etc/rc1.d/ /etc/smrsh/ /etc/X11/ /etc/cron.hourly/ /etc/init.d/ /etc/pam.d/ /etc/rc2.d/ /etc/ssh/ /etc/xdg/ /etc/cron.monthly/ /etc/iproute2/ /etc/pkcs11/ /etc/rc3.d/ /etc/ssl/ /etc/xinetd.d/ /etc/cron.weekly/ /etc/kernel/ /etc/pki/ /etc/rc4.d/ /etc/statetab.d/ /etc/yum/ /etc/dbus-1/ /etc/krb5.conf.d/ /etc/plymouth/ /etc/rc5.d/ /etc/sudoers.d/ /etc/yum.repos.d/ /etc/default/ /etc/ld.so.conf.d/ /etc/pm/ /etc/rc6.d/ /etc/sysconfig/ /etc/depmod.d/ /etc/libnl/ /etc/polkit-1/ /etc/rc.d/ /etc/sysctl.d/
五、
1.创建用户gentoo,附加组为bin和root, 默认shell为/bin/csh, 注释信息为"Gentoo Distribution"
[root@centos7 ~]# useradd -G bin,root -s /bin/csh -c "Gentoo Distribution" gentoo [root@centos7 ~]# id -a gentoo uid=1001(gentoo) gid=1001(gentoo) groups=1001(gentoo),0(root),1(bin) [root@centos7 ~]# cat /etc/passwd | grep gentoo gentoo:x:1001:1001:Gentoo Distribution:/home/gentoo:/bin/csh
2.创建下面的用户、组和组成员关系
名字为webs的组
用户nginx,使用webs作为附加组
用户varnish,使用webs作为附加组
用户mysql,不可交互登录系统，且不是webs的成员，nginx, varnish, mysq密码都是123456
[root@centos7 ~]# groupadd webs [root@centos7 ~]# useradd -G webs nginx [root@centos7 ~]# useradd -G webs varnish [root@centos7 ~]# useradd -s /bin/false mysql [root@centos7 ~]# echo -e "123456 123456" |passwd nginx Changing password for user nginx. New password: BAD PASSWORD: The password is shorter than 8 characters Retype new password: passwd: all authentication tokens updated successfully. [root@centos7 ~]# echo -e "123456 123456" |passwd varnish Changing password for user varnish. New password: BAD PASSWORD: The password is shorter than 8 characters Retype new password: passwd: all authentication tokens updated successfully. [root@centos7 ~]# echo -e "123456 123456" |passwd mysql Changing password for user mysql. New password: BAD PASSWORD: The password is shorter than 8 characters Retype new password: passwd: all authentication tokens updated successfully. [root@centos7 ~]# tail -n 4 /etc/passwd gentoo:x:1001:1001:Gentoo Distribution:/home/gentoo:/bin/csh nginx:x:1002:1003::/home/nginx:/bin/bash varnish:x:1003:1004::/home/varnish:/bin/bash mysql:x:1004:1005::/home/mysql:/bin/false
六、
1.当用户docker对/testdir目录无执行权限时，意味着无法做哪些操作?
无法进入目录
无法删除目录内的文件
无法在目录内创建新文件
2.当用户mongodb对/testdir目录无读权限时，意味着无法做哪些操作?
无法查看目录内的文件列表
3.当用户redis对testdir目录无写权限时，该目录下的只读文件file1是否可修改和删除?
不可以删除文件，但是可以修改文件
4.当用户zabbix对/testdir目录有写和执行权限时，该目录下的只读文件file1是否可修改和删除?
可以修改和删除
5.复制/et/fstab文件到/var/tmp下，设置文件所有者为tomcat读写权限，所属组为apps组有读写
权限，其他人无权限
[root@centos7 ~]# useradd tomcat [root@centos7 ~]# groupadd apps [root@centos7 ~]# cp /etc/passwd /var/tmp/ [root@centos7 ~]# cd /var/tmp/ [root@centos7 tmp]# ll total 4 -rw-r--r--. 1 root root 1271 Mar 25 14:12 passwd [root@centos7 tmp]# chown tomcat.apps passwd [root@centos7 tmp]# ll total 4 -rw-r--r--. 1 tomcat apps 1271 Mar 25 14:12 passwd [root@centos7 tmp]# chmod 660 passwd [root@centos7 tmp]# ll total 4 -rw-rw----. 1 tomcat apps 1271 Mar 25 14:12 passwd
6.误删除了用户git的家目录,请重建并恢复该用户家目录及相应的权限属性
[root@centos7 data]# useradd git [root@centos7 data]# ll /home/ total 0 drwx------. 3 docker docker 77 Mar 25 14:07 docker drwx------. 2 gentoo gentoo 62 Mar 24 17:23 gentoo drwx------. 2 git git 62 Mar 25 14:15 git drwx------. 2 mysql mysql 62 Mar 24 17:31 mysql drwx------. 2 nginx nginx 83 Mar 24 17:33 nginx drwx------. 2 tomcat tomcat 62 Mar 25 14:12 tomcat drwx------. 2 varnish varnish 83 Mar 24 17:33 varnish drwx------. 2 wang wang 102 Mar 22 14:02 wang [root@centos7 data]# man useradd [root@centos7 data]# rm -rf /home/git/ [root@centos7 home]# mkdir git [root@centos7 home]# cp -a /etc/skel/. /home/git/ [root@centos7 home]# chmod 700 git/ [root@centos7 home]# chown -R git:git git/
七、
1.在/testdir/dir里创建的新文件自动属于webs组，组apps的成员如: tomcat能对这些新文件有读写
权限，组dbs的成员如: mysq|只能对新文件有读权限， 其它用户(不属于webs,apps,dbs) 不能
访问这个文件夹
[root@centos7 data]# mkdir testdir/dir -p [root@centos7 data]# groupadd webs [root@centos7 testdir]# groupadd dbs [root@centos7 testdir]# chmod g+s dir/ [root@centos7 testdir]# ll total 0 drwxr-sr-x. 2 root root 6 Mar 25 14:44 dir [root@centos7 testdir]# chgrp webs dir/ [root@centos7 testdir]# ll total 0 drwxr-sr-x. 2 root webs 6 Mar 25 14:44 dir [root@centos7 testdir]# touch dir/1.txt [root@centos7 testdir]# ll dir/ total 0 -rw-r--r--. 1 root webs 0 Mar 25 14:45 1.txt [root@centos7 testdir]# ll total 0 drwxr-sr-x. 2 root webs 19 Mar 25 14:45 dir [root@centos7 testdir]# chmod o=- dir/ [root@centos7 testdir]# ll total 0 drwxr-s---. 2 root webs 19 Mar 25 14:45 dir [root@centos7 testdir]# usermod tomcat -G apps [root@centos7 testdir]# id tomcat uid=1006(tomcat) gid=1007(tomcat) groups=1007(tomcat),1008(apps) [root@centos7 testdir]# setfacl -m g:apps:rw dir/ [root@centos7 testdir]# setfacl -m g:dbs:r dir/ [root@centos7 testdir]# getfacl dir/ # file: dir/ # owner: root # group: webs # flags: -s- user::rwx group::r-x group:apps:rw- group:dbs:r-- mask::rwx other::---
2.误将/bin/chmod文件的执行权限删除，如何恢复?
1.从别的机器拷贝了一个
#2.使用acl [root@centos7 data]# ll /bin/chmod -rwxr-xr-x. 1 root root 58592 Aug 20 2019 /bin/chmod [root@centos7 data]# chmod a-x /bin/chmod [root@centos7 data]# ll /bin/chmod -rw-r--r--. 1 root root 58592 Aug 20 2019 /bin/chmod [root@centos7 data]# touch 1.txt [root@centos7 data]# chmod 777 1.txt -bash: /usr/bin/chmod: Permission denied [root@centos7 data]# setfacl -m u:root:rwx /bin/chmod [root@centos7 data]# getfacl /bin/chmod getfacl: Removing leading '/' from absolute path names # file: bin/chmod # owner: root # group: root user::rw- user:root:rwx group::r-- mask::rwx other::r-- [root@centos7 data]# chmod 777 1.txt [root@centos7 data]# ll total 0 -rwxrwxrwx. 1 root root 0 Mar 25 15:11 1.txt [root@centos7 data]# chmod a+x /bin/chmod [root@centos7 data]# ll /bin/chmod -rwxrwxr-x+ 1 root root 58592 Aug 20 2019 /bin/chmod [root@centos7 data]#