（6） Test command

#!/bin/bash

#  Used to check whether the condition is true ： The number 、 Characters and files 
# （ One ） The number 
:<<EOF
-eq	 Equal is true 
-ne	 True if not equal 
-gt	 Greater than is true 
-ge	 True if greater than or equal to 
-lt	 Less than is true 
-le	 True if less than or equal to 
EOF

num1=100
num2=200
if test ${
    num1} -eq ${
    num2}
then
  echo  Two numbers are equal 
else
  echo  Two numbers are not equal 
fi
# (1) In code  []  Perform basic arithmetic operations , But it's best to use (())
echo "(num1+num2)*num1=$(((num1+num2)*num1))"

# (2)test  You can use [] Instead of ,[] A space is required before and after the inside 
if [ ${
    num1} -eq ${
    num2} ]
then
  echo  Two numbers are equal xxxx
else
  echo  Two numbers are not equal xxxx
fi
# （ Two ） String test 
:<<EOF
=     # Equality is true 
!=    # Inequality is true 
-z    # String length is 0 It is true 
-n    # String length is not 0 It is true 
EOF
str1="runoob1"
str2="runoob2"
if test $str1 = $str2
then
  echo str1=str2
else
  echo str1 It's not equal to str2
fi

#  String length 
if test -z $str2
then
  echo str2 is empty
else
  echo str2 is not empty
fi

# （ 3、 ... and ） File test 
:<<EOF
-e  file name 	 True if the file exists 
-r  file name 	 True if the file exists and is readable 
-w  file name 	 True if the file exists and is writable 
-x  file name 	 True if the file exists and is executable 
-s  file name 	 True if the file exists and has at least one character 
-d  file name 	 True if the file exists and is a directory 
-f  file name 	 True if the file exists and is a normal file 
-c  file name 	 True if the file exists and is a special character file 
-b  file name 	 True if the file exists and is a block special file 
EOF
if test -e ./myfile
then
  echo myfile There is 
else
  echo myfile non-existent 
fi

# (3) If  then  If you start a new line  then  There is no need to add  ;  Otherwise, it needs to be in  then  Before to add  ;
if [ -d "/data/" ];then
  echo "data Folder exists "
else
  echo "data Folder does not exist "
fi
# (4)"/data/"  Double quotation marks can be removed .


# （ Four ） And or not  -a -o !
# Shell  It also provides ( -a )、 or ( -o )、 Not ( ! ) Three logical operators are used to connect test conditions 
#  Its priority is ： !  The highest , -a  second , -o  The minimum 
if [ -e ./notFile -o -e ./myfiel ]; then
  echo " At least one file exists "
else
  echo " It doesn't exist "
fi