linux Bash编程基本语法
定义和使用变量
var="123"
echo $var
readonly var -->只读变量
unset var -->删除变量
拼接字符串 greeting="hello,"$yourname"!"
数组 array_name=(value0 value1 value2 value3)
1.取数组 valuen=$(array_name[n])
2.单独赋值 array_name[0]=value0
实战
创建数组
a=(a b c)
读取值
echo ${a[0]}
-->a
manshuo@Dashuo:~$ echo ${a[1]}
-->b
manshuo@Dashuo:~$ echo ${a[2]}
-->c
manshuo@Dashuo:~$ echo ${a[3]}
manshuo@Dashuo:~$ echo ${a[*]}
-->a b c
if condition ;
then
command 1;
fi
eg:
比较a b值大小:
if [ $a -eq $b ];then echo "equal";elif [ $a -gt $b ]; then echo "a>b";elif [ $a -lt $b ]; then echo "a<b"; fi
#空格必须有,不然会报错
for
for var in item1 item2 ..
do
command1
command2
done
eg:
for loop in 1 2 3 4
do
echo "hello"
done
打印所有1.txt的内容
for i in $(cat 1.txt);
do
echo $i;
done
while condition
do
command
done
eg:
int=1
while (( $int<=5 ))
do
echo $int
let "int++"
done
循环读取文件内容并输出
while read line;do echo $line;done<dir.txt