13 shell script+

比较操作
-eq或= 
-ne或!=
-gt或>
-lt或<
-ge  大于或等于
-le   小于或等于
-z    为空
-n    不为空

1 s5
#!/bin/sh
a=10
b=5
if [ $a -eq $b ]
then
  echo "a=b"
else if [ $a -le $b ]
     then
        echo "a<b"
     else
        echo "haha"
     fi
fi

注意:
 在"["和"]"两边都要有空格
 "="做赋值时,"="左右两边不留空格
 "="做判断时,"="左右两边都要留空格
 

2 s6
#!/bin/sh
for day in Sun Mon Tue Wed Thu Fri Sat
do
  echo $day
done

3
while [ condition ]
do
 #code block
done

until [ condition ]
do
  #code block
done

注：while条件为真时执行,until条件为假时执行

4 s7
#!/bin/sh
echo "Hit a key,then hit return"
read Keypress
case "$Keypress" in
  [A-Z]) echo "Uppercase letter";;
  [a-z]) echo "Lowercase letter";;
  [0-9]) echo "Digit";;
  *) echo "Others";;
esac

转载于:https://www.cnblogs.com/mycheetah/archive/2013/04/14/3020118.html