课后作业 练习题

相关练习：

1、file1文件的内容为：”1 2 3 4 5 6 7 8 9 10” 计算出所有数字的总和

echo $[1+2+3+4+5+6+7+8+9+10]

echo "1+2+3+4+5+6+7+8+9+10" | bc

电脑演示

[[email protected] Desktop]# echo $[1+2+3+4+5+6+7+8+9+10]

55

[[email protected] Desktop]#  echo "1+2+3+4+5+6+7+8+9+10" | bc

55

[[email protected] Desktop]#

2、处理字符串“xt.,l 1 jr#!$mn2 c*/fe3 uz4”，只保留其中的数字和空格

echo "xt.,l 1 jr#!$mn2 c*/fe3 uz4" | tr -d "xt.,ljr#!$mnc*/feuz"

电脑演示

[[email protected] Desktop]#  echo "xt.,l 1 jr#!$mn2 c*/fe3 uz4" | tr -d "xt.,ljr#!$mnc*/feuz"

echo "xt.,l 1 jr#bcmn2 c*/fe3 uz4" | tr -d "xt.,ljr#bcmnc*/feuz"

1 2 3 4

[[email protected] Desktop]#

3、将PATH变量每个目录显示在独立的一行

echo $PATH | tr ":" "\n"

电脑演示

[[email protected] Desktop]#   echo $PATH | tr ":" "\n"

/usr/lib64/qt-3.3/bin

/usr/local/sbin

/usr/sbin

/sbin

/usr/local/bin

/usr/bin

/bin

/root/bin

[[email protected] Desktop]#

4、删除指定文件的空行

cat /root/install.log | tr -s "\n"【利用-s的循环】

电脑演示

[[email protected] Desktop]#  cat /root/install.log | tr -s "\n"

{

333

anaconda-ks.cfg

Desktop

Documents

Downloads

f1

f22

f99

f[a,b,c,d,e,f]

history.log

install.log

install.log.syslog

Music

nusers

Pictures

Public

Templates

Videos

[[email protected] Desktop]#

5、将文件中每个单词（字母）显示在独立的一行，并无空行

cat /root/install.log | tr " " "\n" | tr -s "\n"

电脑演示

[[email protected] Desktop]#  cat /root/install.log | tr " " "\n" | tr -s "\n"

{

333

anaconda-ks.cfg

Desktop

Documents

Downloads

f1

f22

f99

f[a,b,c,d,e,f]

history.log

install.log

install.log.syslog

Music

nusers

Pictures

Public

Templates

Videos

6、创建用户tiantian，附加组为bin和root，默认shell为/bin/csh，注释信息为"Tiantian Distribution"

useradd -G bin,root -s /bin/csh -c "Tiantian Distribution" tiantian

电脑演示

[[email protected] Desktop]#   useradd -G bin,root -s /bin/csh -c "Tiantian Distribution" tiantian

rtkit:x:499:499:RealtimeKit:/proc:/sbin/nologin

avahi-autoipd:x:170:170:Avahi IPv4LL Stack:/var/lib/avahi-autoipd:/sbin/nologin

vcsa:x:69:69:virtual console memory owner:/dev:/sbin/nologin

abrt:x:173:173::/etc/abrt:/sbin/nologin

rpcuser:x:29:29:RPC Service User:/var/lib/nfs:/sbin/nologin

nfsnobody:x:65534:65534:Anonymous NFS User:/var/lib/nfs:/sbin/nologin

haldaemon:x:68:68:HAL daemon:/:/sbin/nologin

ntp:x:38:38::/etc/ntp:/sbin/nologin

apache:x:48:48:Apache:/var/www:/sbin/nologin

saslauth:x:498:76:Saslauthd user:/var/empty/saslauth:/sbin/nologin

postfix:x:89:89::/var/spool/postfix:/sbin/nologin

mysql:x:27:27:MySQL Server:/var/lib/mysql:/bin/bash

gdm:x:42:42::/var/lib/gdm:/sbin/nologin

pulse:x:497:495:PulseAudio System Daemon:/var/run/pulse:/sbin/nologin

sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin

tcpdump:x:72:72::/:/sbin/nologin

tianya:x:500:500:tianya:/home/tianya:/bin/bash

gentoo:x:501:501:Gentoo Disttibuution:/home/gentoo:/bin/csh

tian:x:502:502::/home/tian:/bin/bash

tiantian:x:503:503:Tiantian Distribution:/home/tiantian:/bin/csh

[[email protected] Desktop]# ^C

[[email protected] Desktop]#

7、创建下面的用户、组和组成员关系

名字为admins 的组

用户natasha，使用admins 作为附属组

用户harry，也使用admins 作为附属组

用户sarah，不可交互登录系统，且不是admins 的成员，natasha，harry，sarah密码都是centos

1 #!/bin/bash

2 groupadd admins

3 useradd -G admins natasha

4 useradd -G admins harry

5 useradd -s /sbin/nologoin sarah

6 echo "centos" | passwd --stdin natasha

7 echo "centos" | passwd --stdin harry

8 echo "centos" | passwd --stdin sarah

电脑演示

[[email protected] Desktop]# nano f1.xt

[[email protected] Desktop]# cat f1.xt

#!/bin/bash

groupadd admins

useradd -G admins natasha

useradd -G admins harry

useradd -s /sbin/nologoin sarah

echo "centos" | passwd --stdin natasha

echo "centos" | passwd --stdin harry

echo "centos" | passwd --stdin