Shell script test and [] and [[ ]] and (()) statement application

Records : 437

Scenario : Shell script test, [], [[]], (()) statement application.

Version : CentOS Linux release 7.9.2009.

1. test and [] and [[]] and (()) statement

test, the test command is used to check whether a certain condition is true. You can perform tests on numerical values, characters, and files.

[], the test command is abbreviated as []. Supports relational operators, etc.

[[ ]], supports logical operators.

Format: test expression

Format: [expression]

Format: [[ expression01 || expression02 ]]

Format: (( expression01 && expression02 ))

Note: There is a space between [] and expression, these two spaces are required, otherwise a syntax error will result during execution.

2. Use the test command

2.1 Script

Screenplay name: b2023052901.sh

Script content:

#!/bin/bash

echo "请分别输入GDP,人口数,以空格分割:"
read gdp population

#使用test表达式
if test ${gdp} -gt 30000 && test ${population} -lt 2000 ;then
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万,这是一类城市."
elif test ${gdp} -gt 20000 && test ${population} -lt 1500 ;then
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万,这是二类城市."
elif test ${gdp} -gt 10000 && test ${population} -lt 1000 ;then
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万,这是三类城市."
elif test ${gdp} -gt 5000 && test ${population} -lt 500 ;then
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万,这是四类城市."
else
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万."
fi

2.2 Execution and output

Execute the command: bash b2023052901.sh

Results of the:

[root@hadoop211 tutorial]# bash b2023052901.sh 
请分别输入GDP,人口数,以空格分割:
30001 1999
城市GDP: 30001 亿, 人口: 1999 万,这是一类城市.

3. Use []

3.1 Script

Screenplay name: b2023052902.sh

Script content:

#!/bin/bash

echo "请分别输入GDP,人口数,以空格分割:"
read gdp population

#使用[]表达式
if [ ${gdp} -gt 30000 ] && [ ${population} -lt 2000 ] ;then
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万,这是一类城市."
elif [ ${gdp} -gt 20000 ] && [ ${population} -lt 1500 ] ;then
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万,这是二类城市."
elif [ ${gdp} -gt 10000 ] && [ ${population} -lt 1000 ] ;then
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万,这是三类城市."
elif [ ${gdp} -gt 5000 ] && [ ${population} -lt 500 ] ;then
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万,这是四类城市."
else
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万."
fi

3.2 Execution and output

Execute the command: bash b2023052902.sh

Results of the:

[root@hadoop211 tutorial]# bash b2023052902.sh 
请分别输入GDP,人口数,以空格分割:
20001 1499
城市GDP: 20001 亿, 人口: 1499 万,这是二类城市.

4. Use [[ ]]

4.1 Script

Screenplay name: b2023052903.sh

Script content:

#!/bin/bash

echo "请分别输入GDP,人口数,以空格分割:"
read gdp population

#使用[[]]表达式
if [[ ${gdp} -gt 30000 && ${population} -lt 2000 ]] ;then
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万,这是一类城市."
elif [[ ${gdp} -gt 20000 && ${population} -lt 1500 ]] ;then
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万,这是二类城市."
elif [[ ${gdp} -gt 10000 && ${population} -lt 1000 ]] ;then
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万,这是三类城市."
elif [[ ${gdp} -gt 5000 && ${population} -lt 500 ]] ;then
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万,这是四类城市."
else
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万."
fi

4.2 Execution and output

Execute the command: bash b2023052903.sh

Results of the:

[root@hadoop211 tutorial]# bash b2023052903.sh 
请分别输入GDP,人口数,以空格分割:
10001 999
城市GDP: 10001 亿, 人口: 999 万,这是三类城市.

5. Use (())

5.1 Script

Screenplay name: b2023052904.sh

Script content:

#!/bin/bash

echo "请分别输入GDP,人口数,以空格分割:"
read gdp population
#使用(())表达式
if (( ${gdp} > 30000 && ${population} < 2000)) ;then
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万,这是一类城市."
elif (( ${gdp} > 20000 && ${population} < 1500)) ;then 
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万,这是二类城市."
elif (( ${gdp} > 10000 && ${population} < 1000)) ;then 
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万,这是三类城市."
elif (( ${gdp} > 5000 && ${population} < 500)) ;then 
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万,这是四类城市."
else
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万."
fi

5.2 Execution and output

Execute the command: bash b2023052904.sh

Results of the:

[root@hadoop211 tutorial]# bash b2023052904.sh 
请分别输入GDP,人口数,以空格分割:
5001 499
城市GDP: 5001 亿, 人口: 499 万,这是四类城市.

6. Test and [] and [[]] and (()) statements are used in conjunction

6.1 Script

Screenplay name: b2023052905.sh

Script content:

#!/bin/bash

echo "请分别输入GDP,人口数,以空格分割:"
read gdp population
#test和[]和[[]]和(())语句联合使用
if test ${gdp} -gt 30000 && test ${population} -lt 2000 ;then
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万,这是一类城市."
elif [ ${gdp} -gt 20000 ] && [ ${population} -lt 1500 ] ;then
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万,这是二类城市."
elif [[ ${gdp} -gt 10000 && ${population} -lt 1000 ]] ;then
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万,这是三类城市."
elif (( ${gdp} > 5000 && ${population} < 500)) ;then 
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万,这是四类城市."
else
  echo "城市GDP: ${gdp} 亿, 人口: ${population} 万."
fi

6.2 Execution and output

Execute the command: bash b2023052905.sh

Results of the:

[root@hadoop211 tutorial]# bash b2023052905.sh 
请分别输入GDP,人口数,以空格分割:
30001 1999
城市GDP: 30001 亿, 人口: 1999 万,这是一类城市.
[root@hadoop211 tutorial]# bash b2023052905.sh 
请分别输入GDP,人口数,以空格分割:
20001 1499
城市GDP: 20001 亿, 人口: 1499 万,这是二类城市.
[root@hadoop211 tutorial]# bash b2023052905.sh 
请分别输入GDP,人口数,以空格分割:
10001 999
城市GDP: 10001 亿, 人口: 999 万,这是三类城市.
[root@hadoop211 tutorial]# bash b2023052905.sh 
请分别输入GDP,人口数,以空格分割:
5001 499
城市GDP: 5001 亿, 人口: 499 万,这是四类城市.
[root@hadoop211 tutorial]# bash b2023052905.sh 
请分别输入GDP,人口数,以空格分割:
30001 2001
城市GDP: 30001 亿, 人口: 2001 万.

Above, thanks.

May 29, 2023

Shell script test and [] and [[ ]] and (()) statement application

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