过程式编程
选择执行
顺序执行: if, case
循环执行: for, while, until
for循环列表
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8
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for
i
in
LIST;
do
循环体
done
for
i
in
LIST
do
循环体
done
|
while循环
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while
CONDITION;
do
循环体
done
while
CONDITION
do
循环体
done
CONDITION 循环控制条件,每执行一次循环体，需要再次进行判断
true
时，执行一次循环
false
时，退出循环
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练习：100以内所有正整数之和
练习: 100以内所有偶数和
练习:添加10个用户
练习:通过ping命令探测172.16.250.1-254范围内的所有主机的在线状态.用while循环
练习：打印9x9乘法表
练习：利用RANDOM生成10个随机数，输出这10个数字，并显示其中最大者和最小者
练习：100以内所有正整数之和
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7
8
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#!/bin/bash
#
declare
-i
sum
=0
for
i
in
{1..100};
do
let
sum
=$
sum
+1
done
echo
$i
echo
"summary: $sum"
|
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11
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#!/bin/bash
#
declare -i sum=
0
declare -i i=
1
while
[ $i -le
100
];
do
sum=$[$sum+$i]
let i++
done
echo $i
echo
"summary: $sum"
|
练习: 100以内所有偶数和
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2
3
4
5
6
7
8
9
10
11
|
#!/bin/bash
#
declare -i sum=
0
declare -i i=
2
while
[ $i -le
100
];
do
sum=$[$sum+$i]
let i+=
2
done
echo $i
echo
"summary: $sum"
|
练习:添加10个用户user1-user10
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12
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#!/bin/bash
#
declare
-i i=1
declare
-i
users
=0
while
[ $i -
le
10 ];
do
id
user$i &>
/dev/null
retval=$?
[ $retval -
ne
0 ] &&
useradd
user$i &>
/dev/null
[ $? -
eq
0 ] &&
echo
"Add user user$i finished"
&&
let
users
=$
users
+1
done
echo
"Add $users users"
|
练习:通过ping命令探测172.16.250.1-254范围内的所有主机的在线状态.用while循环
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17
18
|
#!/bin/bash
#
declare -i IP=
'172.16.250.'
declare -i i=
1
declare -i uphosts=
0
declare -i downhosts=
0
while
[ $i -le
254
];
do
if
ping -c
1
-w
1
$IP$i &> /dev/
null
; then
echo
"$IP$i is up"
let uphosts++
else
echo
"$IP$i is down"
let downhosts++
fi
done
echo
"uphosts: $uphosts"
echo
"downhosts: $downhosts"
|
练习：打印9x9乘法表
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2
3
4
5
6
7
8
9
|
#!/bin/bash
#
for
i
in
{
1
..
9
};
do
for
j
in
$(seq
1
1
$i);
do
echo -ne
"${j}X${i}=$[$i*$j]\t"
j=$(($j+
1
))
done
echo
done
|
|
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3
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7
8
9
10
11
12
|
#!/bin/bash
#
declare -i i=
1
while
[ $i -le
9
];
do
declare -i j=
1
while
[ $j -le $i ];
do
echo -ne
"${j}X${i}=$[$i*$j]\t"
j=$(($j+
1
))
done
echo
i=$(expr $i +
1
)
done
|
练习：利用RANDOM生成10个随机数，输出这10个数字，并显示其中最大者和最小者
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|
#!/bin/bash
#
declare -i max=
declare -i min=
declare -i i=
1
declare -i random
while
[ $i -le
10
];
do
random=$RANDOM
echo $random
if
[ $i -eq
1
]; then
max=$random
min=$max
fi
if
[ $i -gt
1
]; then
if
[ $random -gt $max ]; then
max=$random
fi
if
[ $random -lt $min ]; then
min=$random
fi
fi
let i++
done
echo
"max: $max"
echo
"min: $min"
==========================================
#!/bin/bash
#
declare -i max=
declare -i min=
declare -i i=
1
declare -i random
while
[ $i -le
10
];
do
random=$RANDOM
echo $random
if
[ $i -eq
1
]; then
max=$random
min=$max
fi
if
[ $random -gt $max ]; then
max=$random
fi
if
[ $random -lt $min ]; then
min=$random
fi
let i++
done
echo
"max: $max"
echo
"min: $min"
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本文转自 lccnx 51CTO博客，原文链接：http://blog.51cto.com/sonlich/1964037，如需转载请自行联系原作者
