shell编程实战学习（2）
一、Shell read的使用
1.1.1 read的使用
- read是bash的内置命名，可也通过复制或传参的来获取变量
| 参数 |
作用 |
| -p |
设置提示信息 |
| -t |
设置超时时间 |
- 赋值运算
[root@web01 /server/scripts]# cat read.sh
#!/bin/bash
a=9
b=6
#read -p "please input two nmb: " a b
echo "a+b=$((a+b))"
echo "a*b=$((a*b))"
echo "a/b=$((a/b))"
echo "a-b=$((a-b))"
echo "a%b=$((a%b))"
echo "a**b=$((a**b))"
[root@web01 /server/scripts]# sh read.sh
a+b=15
a*b=54
a/b=1
a-b=3
a%b=3
a**b=531441
- read读入运算
[root@web01 /server/scripts]# cat read.sh
#!/bin/bash
read -p "please input two nmb: " a b
echo "a+b=$((a+b))"
echo "a*b=$((a*b))"
echo "a/b=$((a/b))"
echo "a-b=$((a-b))"
echo "a%b=$((a%b))"
echo "a**b=$((a**b))"
- 脚本传参运算
[root@web01 /server/scripts]# cat chuancan.sh
#!/bin/bash
echo "a+b=$(($1+$2))"
echo "a*b=$(($1*$2))"
echo "a-b=$(($1-$2))"
echo "a/b=$(($1/$2))"
echo "a%b=$(($1%$2))"
echo "a**b=$(($1**$2))"
[root@web01 /server/scripts]# sh chuancan.sh 9 6
a+b=15
a*b=54
a-b=3
a/b=1
a%b=3
a**b=531441
[root@web01 /server/scripts]# sh chuancan.sh 10 5
a+b=15
a*b=50
a-b=5
a/b=2
a%b=0
a**b=100000
二、Shell的条件测试与比较
2.1.1 条件测试语法
| 条件测试语法 |
说明 |
| test |
这是利用test命令进行测试条件表达式的方法。test命令和“<测试表达式>” 之间至少有一个空格 |
| [] |
这是通过[]（单中括号）进行条件表达式的方法，和test命令的用法相同 之间至少有一个空格 |
| [[]] |
这是通过[[]]（双中括号）进行条件表达式的方法，比test,[]更新的语法格式 之间至少有一个空格 |
| (()) |
通过(())（双小括号）进行测试条件表达式的方法，一般用于if语句里 不需要空格 |
- test 语法
[root@web01 /server/scripts]# test -f linux && echo 0 || echo 1
1
[root@web01 /server/scripts]# test ! -f linux && echo 0 || echo 1
0
- [] 语法
[root@web01 /server/scripts]# [ -f linux ] && echo 0 || echo 1
1
[root@web01 /server/scripts]# [ ! -f linux ] && echo 0 || echo 1
0
- [[]] 语法
[root@web01 /server/scripts]# [[ -f linux ]] && echo 0 || echo 1
1
[root@web01 /server/scripts]# [[ ! -f linux ]] && echo 0 || echo 1
0
- (()) 语法
[root@web01 /server/scripts]# ((6 > 5)) && echo 0 || echo 1
0
[root@web01 /server/scripts]# ((6 == 5)) && echo 0 || echo 1
1
- man帮助
-n STRING
the length of STRING is nonzero
STRING equivalent to -n STRING
-z STRING
the length of STRING is zero
STRING1 = STRING2
the strings are equal
STRING1 != STRING2
the strings are not equal
INTEGER1 -eq INTEGER2
INTEGER1 is equal to INTEGER2
INTEGER1 -ge INTEGER2
INTEGER1 is greater than or equal to INTEGER2
INTEGER1 -gt INTEGER2
INTEGER1 is greater than INTEGER2
INTEGER1 -le INTEGER2
INTEGER1 is less than or equal to INTEGER2
INTEGER1 -lt INTEGER2
INTEGER1 is less than INTEGER2
INTEGER1 -ne INTEGER2
INTEGER1 is not equal to INTEGER2
FILE1 -ef FILE2
FILE1 and FILE2 have the same device and inode numbers
FILE1 -nt FILE2
FILE1 is newer (modification date) than FILE2
FILE1 -ot FILE2
FILE1 is older than FILE2
-b FILE
FILE exists and is block special
-c FILE
FILE exists and is character special
-d FILE
FILE exists and is a directory
-e FILE
FILE exists
-f FILE
FILE exists and is a regular file
-g FILE
FILE exists and is set-group-ID
-G FILE
FILE exists and is owned by the effective group ID
-h FILE
FILE exists and is a symbolic link (same as -L)
-k FILE
FILE exists and has its sticky bit set
-L FILE
FILE exists and is a symbolic link (same as -h)
-O FILE
FILE exists and is owned by the effective user ID
-p FILE
FILE exists and is a named pipe
-r FILE
FILE exists and read permission is granted
-s FILE
FILE exists and has a size greater than zero
-S FILE
FILE exists and is a socket
-t FD file descriptor FD is opened on a terminal
-u FILE
FILE exists and its set-user-ID bit is set
-w FILE
FILE exists and write permission is granted
-x FILE
FILE exists and execute (or search) permission is granted
- 使用
[root@web01 /server/scripts]# mkdir linux
[root@web01 /server/scripts]# [ -e linux ] && echo 0 || echo 1
0
[root@web01 /server/scripts]# [ -d linux ] && echo 0 || echo 1
0
[root@web01 /server/scripts]# [ -f linux ] && echo 0 || echo 1
1
[root@web01 /server/scripts]# [ -w linux ] && echo 0 || echo 1
0
[root@web01 /server/scripts]# [ -L linux ] && echo 0 || echo 1
1
[root@web01 /server/scripts]# [ -r linux ] && echo 0 || echo 1
0
- 特殊表达式
[ 条件1 ] && {
命令1
命令2
命令3
}
如果条件成立，那么执行三个命令。
if [ 条件1 ]
then
命令1
命令2
命令3
fi
[ 条件1 ] || {
命令1
命令2
命令3
}
如果表达式不成立，那么执行三个命令。
[ -L oldboy ] && echo 1 || echo 0
[ 条件1 ] && {
命令1
命令2
} || {
命令3
}
如果条件成立，那么执行命令1命令2，否则执行命令3。
- 字符串比较
| 符号 |
作用 |
| -z |
字符串长度为空，为真 |
| -n |
字符串长度不为空，为真 |
| “字符” = “字符” |
两个字符串相等为真 |
| “字符” != “字符” |
两个字符串不相等为真 |
- 测试
[root@web01 /server/scripts]# a=linux
[root@web01 /server/scripts]# [ -z "$a" ] && echo 0 || echo 1
1
[root@web01 /server/scripts]# [ -n "$a" ] && echo 0 || echo 1
0
[root@web01 /server/scripts]# [ "$a" = "linux" ] && echo 0 || echo 1
0
[root@web01 /server/scripts]# [ "$a" != "linux" ] && echo 0 || echo 1
1
- 判断一个数是否是整数
[root@web01 /server/scripts]# cat read.sh
#!/bin/bash
read -p "please input two nmb: " a b
[ -n "$a" -a -n "$b" ] || {
echo "please input two nmb"
exit 0
}
expr $a + 1 &>/dev/null
[ $? -eq 0 ] || {
echo "please input two int nmb: "
exit 0
}
expr $b + 1 &>/dev/null
[ $? -eq 0 ] || {
echo "please input two int nmb: "
exit 0
}
echo "a+b=$((a+b))"
echo "a*b=$((a*b))"
echo "a/b=$((a/b))"
echo "a-b=$((a-b))"
echo "a%b=$((a%b))"
echo "a**b=$((a**b))"
# 简化
[root@web01 /server/scripts]# cat read.sh
#!/bin/bash
read -p "please input two nmb: " a b
[ -n "$a" -a -n "$b" ] || {
echo "please input two nmb"
exit 0
}
expr $a + $b + 9 &>/dev/null
[ $? -eq 0 ] || {
echo "please input two int nmb: "
exit 0
}
echo "a+b=$((a+b))"
echo "a*b=$((a*b))"
echo "a/b=$((a/b))"
echo "a-b=$((a-b))"
echo "a%b=$((a%b))"
echo "a**b=$((a**b))"
#什么都没输入
[root@web01 /server/scripts]# sh read.sh
please input two nmb:
please input two nmb
#输入字符
[root@web01 /server/scripts]# sh read.sh
please input two nmb: k 3
please input two nmb:
#输入两个整数
[root@web01 /server/scripts]# sh read.sh
please input two nmb: 9 6
a+b=15
a*b=54
a/b=1
a-b=3
a%b=3
a**b=531441
11.传参脚本
[root@web01 /server/scripts]# cat chuancan.sh
#!/bin/bash
[ $# -eq 2 ] ||{
echo "pelase inpou tow nmb:"
exit 0
}
expr $1 + $2 + 5 &>/dev/null
[ $? -eq 0 ] ||{
echo "pelase inpou tow nmb:"
exit 1
}
echo "a+b=$(($1+$2))"
echo "a*b=$(($1*$2))"
echo "a-b=$(($1-$2))"
echo "a/b=$(($1/$2))"
echo "a%b=$(($1%$2))"
echo "a**b=$(($1**$2))"
2.1.2 整数二元比较操作符
1.二元整数比较
| 数学符号表示方式 |
字母表示方式 |
| > |
-gt |
| >= |
-ge |
| < |
-lt |
| <= |
-le |
| = |
-eq |
| != |
-ne |
- 例子
#[]
[root@web01 /server/scripts]# [ 1 -ne 2 ] && echo 1 || echo 0
1
[root@web01 /server/scripts]# [ 1 -eq 2 ] && echo 1 || echo 0
0
[root@web01 /server/scripts]# [ 1 -ne 2 ] && echo 1 || echo 0
1
[root@web01 /server/scripts]# [ 1 -le 2 ] && echo 1 || echo 0
1
[root@web01 /server/scripts]# [ 1 -ge 2 ] && echo 1 || echo 0
0
[root@web01 /server/scripts]# [ 1 -gt 2 ] && echo 1 || echo 0
0
[root@web01 /server/scripts]# [ 1 -lt 2 ] && echo 1 || echo 0
1
[root@web01 /server/scripts]# [ 1 \< 2 ] && echo 1 || echo 0 #注意如果想用数学比较符 比较符需要转移
1
#[[]]
[root@web01 /server/scripts]# [[ 1 < 2 ]] && echo 1 || echo 0
1
[root@web01 /server/scripts]# [[ 3 < 2 ]] && echo 1 || echo 0
0
[root@web01 /server/scripts]# [[ 3 = 2 ]] && echo 1 || echo 0
[root@web01 /server/scripts]# [[ 3 -eq 2 ]] && echo 1 || echo 0
0
[root@web01 /server/scripts]# [[ 3 -ne 2 ]] && echo 1 || echo 0
1
#(())
[root@web01 /server/scripts]# ((3 > 2)) && echo 1 || echo 0
1
[root@web01 /server/scripts]# ((3 == 2)) && echo 1 || echo 0
0
[root@web01 /server/scripts]# ((3 -ne 2)) && echo 1 || echo 0 #报错不能使用二元整数表达式
-bash: ((: 3 -ne 2: syntax error in expression (error token is "2")
0
[root@web01 /server/scripts]# ((3 -eq 2)) && echo 1 || echo 0
-bash: ((: 3 -eq 2: syntax error in expression (error token is "2")
0
2.1.3 逻辑操作符
| 适用范围test和[]操作符 |
适用范围[[]]和(()) |
说明 |
| -a |
&& |
and 与，两端都为真则真 |
| -o |
|| |
or 或 两端为或有一端为真，则真 |
| ！ |
！ |
not 非 相反为真 |
- 例子
#-a
[root@web01 /server/scripts]# [ -f /etc/profile -a 6 -gt 5 ] && echo 1 || echo 0
1
[root@web01 /server/scripts]# [ -f /etc/profil -a 6 -gt 5 ] && echo 1 || echo 0
0
#-o
[root@web01 /server/scripts]# [ -f /etc/profil -o 6 -gt 5 ] && echo 1 || echo 0
1
#！
[root@web01 /server/scripts]# [ ! -f /etc/profil -o 6 -gt 5 ] && echo 1 || echo 0
1
[root@web01 /server/scripts]# [ ! -f /etc/profil -o 6 -lt 5 ] && echo 1 || echo 0
1
[root@web01 /server/scripts]# [[ -f /etc/profil && 6 -lt 5 ]] && echo 1 || echo 0
0
[root@web01 /server/scripts]# [[ -f /etc/profil || 6 -lt 5 ]] && echo 1 || echo 0
0
[root@web01 /server/scripts]# [[ ! -f /etc/profil || 6 -lt 5 ]] && echo 1 || echo 0
1
- 例子
[root@web01 /server/scripts]# cat diff.sh
#!/bin/bash
[ $1 -eq 1 -o $1 -eq 2 ] &&{
echo "$1"
} || {
echo "input error"
exit 1
}
[root@web01 /server/scripts]# sh diff.sh 1
1
[root@web01 /server/scripts]# sh diff.sh 2
2
[root@web01 /server/scripts]# sh diff.sh 3
input error
##########################################
[root@web01 /server/scripts]# cat diff1.sh
#!/bin/bash
expr $1 + $2 + 3 &>/dev/null
[ $? -eq 0 ] ||{
echo "Usage:$0 num1 num2"
exit 0
}
[ $1 -gt $2 ] && {
echo "$1 > $2"
exit 1
}
[ $1 -lt $2 ] && {
echo "$1 < $2"
exit 2
}
[ $1 -eq $2 ] && {
echo "$1 = $2"
}
[root@web01 /server/scripts]# sh diff1.sh 4 3
4 > 3
[root@web01 /server/scripts]# sh diff1.sh 4 5
4 < 5
[root@web01 /server/scripts]# sh diff1.sh 4 4
4 = 4
[root@web01 /server/scripts]# sh diff1.sh 4 k
Usage:diff1.sh num1 num2
[root@web01 /server/scripts]# sh diff1.sh k k
Usage:diff1.sh num1 num2
[root@web01 /server/scripts]# sh diff1.sh k 4
Usage:diff1.sh num1 num2
2.1.4 read 菜单编写
- 下载菜单编写
[root@web01 /server/scripts]# cat read_install.sh
#!/bin/bash
num1 () {
cat <<END
*****************************
1. PHP install
2. Mysql install
3. Nginx install
4. Tomcat install
5. exit
please input server num:
*****************************
END
}
red () {
read -p "please input num: " a
}
list () {
[ $a -eq 1 ] && {
echo "PHP installed...... "
echo "PHP intsall is ok"
exit 1
}
[ $a -eq 2 ] && {
echo "Nginx installed...... "
echo "Nginx intsall is ok"
exit 2
}
[ $a -eq 3 ] && {
echo "Mysql installed...... "
echo "Mysql intsall is ok"
exit 3
}
[ $a -eq 4 ] && {
echo "Tomcat installed...... "
echo "Tomcat intsall is ok"
exit 4
}
[ $a -eq 5 ] && exit 5
[[ ! $a =~ [1-3] ]] && { #这里就是用到了[[]]的通配符匹配的用法。即a是否为1，2，3
echo "imput error Usage:{1|2|3|4|5}"
}
}
while true
do
num1
red
list
num1
red
list
done
###########################################
[root@web01 /server/scripts]# sh read_install.sh
*****************************
1. PHP install
2. Mysql install
3. Nginx install
4. Tomcat install
5. exit
please input server num:
*****************************
please input num: 3
Mysql installed......
Mysql intsall is ok
[root@web01 /server/scripts]# sh read_install.sh
*****************************
1. PHP install
2. Mysql install
3. Nginx install
4. Tomcat install
5. exit
please input server num:
*****************************
please input num: 4
Tomcat installed......
Tomcat intsall is ok
[root@web01 /server/scripts]# sh read_install.sh
*****************************
1. PHP install
2. Mysql install
3. Nginx install
4. Tomcat install
5. exit
please input server num:
*****************************
please input num: 9
imput error Usage:{1|2|3|4|5}
*****************************
1. PHP install
2. Mysql install
3. Nginx install
4. Tomcat install
5. exit
please input server num:
*****************************
please input num: 5