Linux under Bash programming character test with For Loop statement (v)

Linux under Bash programming character test with For Loop statement (v)

1. Character test:

= =: Test for equality, equality is true, not equal to False

! =: Test Whether it is unequal, not equal to true, etc as false

>,<,>=,<=

-N String: Tests whether the specified string is empty, empty is true, or false

-Z String: Tests whether the specified string is not empty, is not empty, and the null is False

2.for loop: Enter condition, exit condition

for variable in list; Do

Loop body

Done

Build list:

{1..100}: Represents a number from 1 to 100 with a step of 1

SEQ [Start number [step length]] End number for example: SEQ 1 100 default step is 1

DECLARE option variable name = value

Options:

-I declaration As Integer

-X declared as environment variable

3. Experiment: Add 10 users user1 to User10, password with user name; script accepts one parameter:

If it is add:, the user will be added; If it is Del, the user will be deleted, otherwise the parameter error is indicated;

Note that the user exists on the prompt cannot be added, the user does not exist can not delete the user, using the following script implementation:

if [= = ' Add ']; Then

For I in ' seq 1 10 '; Do

if! ID user$i &>/dev/null; Then

Useradd user$i

echo "User$i" | passwd--stdin user$i &>/dev/null

Else

echo "user$i exist"

Fi

Done

elif [= = ' del ']; Then

For I in {1..10}; Do

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

Userdel-r user$i

Else

echo "User$i not Exist"

Fi

Done

Else

echo "Agur is not Add/del!!!"

Fi

4. Experiment: Greet the Bash users in/etc/passwd and count the number of bash users in turn, using the following script:

#!/bin/bash

file=/etc/passwd

Lines= ' Cat $FILE | Wc-l '

Declare-i a=0

For I in ' seq 1 $LINES '; Do

Bsh= ' Head-n $I $FILE | Tail-1 | cut-d:-f7 '

if [[$BSH = = '/bin/bash ']]; Then

echo "Hello, ' head-n $I $FILE | Tail-1 | cut-d:-f1 ', Your Shell is: $BSH "

a=$[$A +1]

Fi

Done

echo "There are $A users"

5. Calculate all the odd and all-even numbers within 100 and display, using the following script:

#!/bin/bash

Os=0 represents even numbers

Js=0 represents an odd number

For I in ' SEQ 1 100 '; Do

If [$[$I%2] = = 0]; Then

os=$[$OS + $I]

Else

js=$[$JS + $I]

Fi

Done

echo "JS SUM is $JS"

echo "OS SUM is $OS"

echo "Js+os is $[$JS + $OS]"

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This article is from the "Xavier Willow" blog, please be sure to keep this source http://willow.blog.51cto.com/6574604/1764290

Linux under Bash programming character test with For Loop statement (v)