循环执行：for, while, until
for循环格式：
for VARAIBLE in LIST; do
循环体
donewhile循环：
while CONDITION; do
循环体
done-
until循环：
until CONDITION; do
循环体
done进入条件：CONDITION测试为”假“
退出条件：CONDITION测试为”真“
练习：
分别使用for, while, until实现
1、分别求100以内所有偶数之和，100以内所奇数之和；
[root@localhost scripts]# ./e13_6_1.sh
for loop : oddsum 2500 , evensum 2550
while loop : oddsum 2500 , evensum 2550
until loop : oddsum 2500 , evensum 2550
[root@localhost scripts]# cat e13_6_1.sh
#!/bin/bash
declare -i sum4for=0 sum4while=0 sum4until=0
for i in {1..100};do
if [ $[$i%2] -eq 1 ];then
let sum4for+=$i
fi
done
echo "for loop : oddsum $sum4for , evensum $[5050-$sum4for]"
let i=1
while [ $i -lt 100 ];do
let sum4while+=i
let i+=2
done
echo "while loop : oddsum $sum4while , evensum $[5050-$sum4while]"
let i=1
until [ $i -gt 100 ];do
let sum4until+=i
let i+=2
done
echo "until loop : oddsum $sum4until , evensum $[5050-$sum4until]"
2、创建10个用户，user101-user110；密码同用户名；
[root@localhost scripts]# bash ./e13_6_2.sh
id: user101: no such user
id: user102: no such user
id: user103: no such user
id: user104: no such user
id: user105: no such user
id: user106: no such user
id: user107: no such user
id: user108: no such user
id: user109: no such user
id: user110: no such user
uid=4007(user101) gid=4007(user101) groups=4007(user101)
uid=4008(user102) gid=4008(user102) groups=4008(user102)
uid=4009(user103) gid=4009(user103) groups=4009(user103)
uid=4010(user104) gid=4010(user104) groups=4010(user104)
uid=4011(user105) gid=4011(user105) groups=4011(user105)
uid=4012(user106) gid=4012(user106) groups=4012(user106)
uid=4013(user107) gid=4013(user107) groups=4013(user107)
uid=4014(user108) gid=4014(user108) groups=4014(user108)
uid=4015(user109) gid=4015(user109) groups=4015(user109)
uid=4016(user110) gid=4016(user110) groups=4016(user110)
uid=4007(user101) gid=4007(user101) groups=4007(user101)
uid=4008(user102) gid=4008(user102) groups=4008(user102)
uid=4009(user103) gid=4009(user103) groups=4009(user103)
uid=4010(user104) gid=4010(user104) groups=4010(user104)
uid=4011(user105) gid=4011(user105) groups=4011(user105)
uid=4012(user106) gid=4012(user106) groups=4012(user106)
uid=4013(user107) gid=4013(user107) groups=4013(user107)
uid=4014(user108) gid=4014(user108) groups=4014(user108)
uid=4015(user109) gid=4015(user109) groups=4015(user109)
uid=4016(user110) gid=4016(user110) groups=4016(user110)
[root@localhost scripts]# cat ./e13_6_2.sh
#!/bin/bash
declare -i i=0
for i in {101..110};do
id user$i || useradd -p user$i user$i
done
i=100
while [ $i -lt 110 ];do
let i+=1
id user$i || useradd -p user$i user$i
done
i=100
until [ $i -ge 110 ];do
let i+=1
id user$i || useradd -p user$i user$i
done
[root@localhost scripts]# bash ./e13_userdel.sh
[root@localhost scripts]# cat ./e13_userdel.sh
#!/bin/bash
for i in `grep -o 'user[0-9]\+' /etc/passwd | uniq`;do
userdel -r $i
done
3、打印九九乘法表；
[root@localhost scripts]# bash e13_6_3.sh
for loop print:
1x1=1
1x2=2 2x2=4
1x3=3 2x3=6 3x3=9
1x4=4 2x4=8 3x4=12 4x4=16
1x5=5 2x5=10 3x5=15 4x5=20 5x5=25
1x6=6 2x6=12 3x6=18 4x6=24 5x6=30 6x6=36
1x7=7 2x7=14 3x7=21 4x7=28 5x7=35 6x7=42 7x7=49
1x8=8 2x8=16 3x8=24 4x8=32 5x8=40 6x8=48 7x8=56 8x8=64
1x9=9 2x9=18 3x9=27 4x9=36 5x9=45 6x9=54 7x9=63 8x9=72 9x9=81
while loop print:
1x1=1
1x2=2 2x2=4
1x3=3 2x3=6 3x3=9
1x4=4 2x4=8 3x4=12 4x4=16
1x5=5 2x5=10 3x5=15 4x5=20 5x5=25
1x6=6 2x6=12 3x6=18 4x6=24 5x6=30 6x6=36
1x7=7 2x7=14 3x7=21 4x7=28 5x7=35 6x7=42 7x7=49
1x8=8 2x8=16 3x8=24 4x8=32 5x8=40 6x8=48 7x8=56 8x8=64
1x9=9 2x9=18 3x9=27 4x9=36 5x9=45 6x9=54 7x9=63 8x9=72 9x9=81
until loop print:
1x1=1
1x2=2 2x2=4
1x3=3 2x3=6 3x3=9
1x4=4 2x4=8 3x4=12 4x4=16
1x5=5 2x5=10 3x5=15 4x5=20 5x5=25
1x6=6 2x6=12 3x6=18 4x6=24 5x6=30 6x6=36
1x7=7 2x7=14 3x7=21 4x7=28 5x7=35 6x7=42 7x7=49
1x8=8 2x8=16 3x8=24 4x8=32 5x8=40 6x8=48 7x8=56 8x8=64
1x9=9 2x9=18 3x9=27 4x9=36 5x9=45 6x9=54 7x9=63 8x9=72 9x9=81
[root@localhost scripts]# cat e13_6_3.sh
#!/bin/bash
declare -i r=0 l=0
echo "for loop print:"
for i in {1..9};do
for j in `seq 1 $i`;do
echo -en "${j}x${i}=$[$i*$j]\t"
done
echo
done
echo -e "\nwhile loop print:"
let r=1
let l=1
while [ $r -lt 10 ];do
while [ $l -le $r ];do
echo -ne "${l}x${r}=$[$r*$l]\t"
let l+=1
done
echo
let l=1
let r+=1
done
let r=1
let l=1
echo -e "\nuntil loop print:"
until [ $r -ge 10 ];do
until [ $l -gt $r ];do
echo -ne "${l}x${r}=$[$r*$l]\t"
let l+=1
done
echo
let l=1
let r+=1
done
4、打印逆序的九九乘法表；
[root@localhost scripts]# bash e13_6_4.sh
for loop print:
1x9=9 2x9=18 3x9=27 4x9=36 5x9=45 6x9=54 7x9=63 8x9=72 9x9=81
1x8=8 2x8=16 3x8=24 4x8=32 5x8=40 6x8=48 7x8=56 8x8=64
1x7=7 2x7=14 3x7=21 4x7=28 5x7=35 6x7=42 7x7=49
1x6=6 2x6=12 3x6=18 4x6=24 5x6=30 6x6=36
1x5=5 2x5=10 3x5=15 4x5=20 5x5=25
1x4=4 2x4=8 3x4=12 4x4=16
1x3=3 2x3=6 3x3=9
1x2=2 2x2=4
1x1=1
while loop print:
1x9=9 2x9=18 3x9=27 4x9=36 5x9=45 6x9=54 7x9=63 8x9=72 9x9=81
1x8=8 2x8=16 3x8=24 4x8=32 5x8=40 6x8=48 7x8=56 8x8=64
1x7=7 2x7=14 3x7=21 4x7=28 5x7=35 6x7=42 7x7=49
1x6=6 2x6=12 3x6=18 4x6=24 5x6=30 6x6=36
1x5=5 2x5=10 3x5=15 4x5=20 5x5=25
1x4=4 2x4=8 3x4=12 4x4=16
1x3=3 2x3=6 3x3=9
1x2=2 2x2=4
1x1=1
until loop print:
1x9=9 2x9=18 3x9=27 4x9=36 5x9=45 6x9=54 7x9=63 8x9=72 9x9=81
1x8=8 2x8=16 3x8=24 4x8=32 5x8=40 6x8=48 7x8=56 8x8=64
1x7=7 2x7=14 3x7=21 4x7=28 5x7=35 6x7=42 7x7=49
1x6=6 2x6=12 3x6=18 4x6=24 5x6=30 6x6=36
1x5=5 2x5=10 3x5=15 4x5=20 5x5=25
1x4=4 2x4=8 3x4=12 4x4=16
1x3=3 2x3=6 3x3=9
1x2=2 2x2=4
1x1=1
[root@localhost scripts]# cat e13_6_4.sh
#!/bin/bash
declare -i r=0 l=0
echo "for loop print:"
for i in `seq 9 -1 1`;do
for j in `seq 1 $i`;do
echo -en "${j}x${i}=$[$i*$j]\t"
done
echo
done
echo -e "\nwhile loop print:"
let r=9
let l=1
while [ $r -ge 1 ];do
while [ $l -le $r ];do
echo -ne "${l}x${r}=$[$r*$l]\t"
let l+=1
done
echo
let l=1
let r-=1
done
let r=9
let l=1
echo -e "\nuntil loop print:"
until [ $r -lt 1 ];do
until [ $l -gt $r ];do
echo -ne "${l}x${r}=$[$r*$l]\t"
let l+=1
done
echo
let l=1
let r-=1
done
