Linux command exercise: For Loop statement practice

Tag: Extract the user under the shell and display the relevant user name

Practice One:

Write a script

1, add 10 users user1 to User10, password with the user name, but requires only the user does not exist in the case can be added;

Extension: accepts a parameter:

Add: Adding User user1. User10

Del: Delete User user1. User10

Other, exit

#!/bin/bash

#program:

#练习添加10个用户

#history Donggen 2016-10-21-22:10

Path=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bash

Export PATH

if [= = = "Add"]; Then

For I in {1..10}; Do

If ID user$i &>/dev/null; then

echo "The user$i is exist"

Else

Useradd user$i

echo "User$i" | passwd--stdin user$i

echo "User$i is add successful"

Fi

Done

elif [= = = "Del"]; Then

For I in {1..10}; Do

If ID user$i &>/dev/null; Then

Userdel-r user$i

echo "User$i is del successful"

Else

echo "NO such user$i"

Fi

Done

Else

echo "The $ not legol command"

Fi

Exercise two:

Write a script

Calculates the total of all positive integers within 100 that can be divisible by 3, modulo, remainder:%

#!/bin/bash

#program:

#计算100以内所有能被三整除的正整数的和

#history Donggen 2016-10-21-23:10

Path=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bash

Export PATH

Declare-i sum=0

For I in {1..100}; Do

Let remainder= $I%3

If [$REMAINDER-eq 0]; Then

Let sum= $SUM + $I

Fi

Done

echo "$SUM"

Exercise Three:

Write a script

Shows all default shell-bash users and default shell-/sbin/nologin users on the current system, respectively.

and statistics of the total number of Shell users, showing the results are as follows:

Bash,3users,they Are:root,redhat,gentoo

Nologin,2users,they are:bin,ftp

#!/bin/bash

#program:

#显示当前shell下面的用户

#history Donggen 2016-10-21-23:40

Path=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bash

Export PATH

bashnum= ' grep '/bash\> '/etc/passwd | Wc-l '

nologinnum= ' grep '/nologin\> '/etc/passwd | Wc-l '

For I in ' seq 1 $BASHNUM '; Do

echo "' grep '/bash\> '/etc/passwd | Head-n $I | Tail-1 | cut-d:-f1 ' ">>/test/bash.txt

Done

For I in ' seq 1 $NOLOGINNUM '; Do

echo "' grep '/nologin\> '/etc/passwd | Head-n $I | Tail-1 | cut-d:-f1 ' ">>/test/nologin.txt

Done

echo "BASH," $BASHNUM "Users,they is:" ' Cat/test/bash.txt '

echo "Nologin," $NOLOGINNUM "Users,they is:" ' Cat/test/nologin.txt '

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Linux command exercise: For Loop statement practice