Use "Go" of the test command in Shelll

The test command in the shell is used to check if a condition is true, and it can be tested in three aspects of numeric, character, and file.

Numerical test

Parameters	Description
-eq	Equals is True
-ne	Not equal to True
-gt	is greater than true
-ge	Greater than or equal to true
-lt	is less than true
-le	is less than or equal to true

For example:

Copy CodeThe code is as follows:
num1=100
num2=100
if test $[num1]-eq $[num2]
Then
Echo ' The numbers is equal! '
Else
Echo ' The numbers is not equal! '
Fi

Output:
The numbers is equal!

String test

Parameters	Description
=	Equals is True
!=	Not Equal is true
-Z String	The string length pseudo is True
-N String	True if the string length is not pseudo

For example:

Copy CodeThe code is as follows:
num1=100
num2=100
if test num1=num2
Then
Echo ' The strings is equal! '
Else
Echo ' The strings is not equal! '
Fi

Output:
The strings is equal!

File test

Parameters	Description
-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 character-specific file
-B file Name	True if the file exists and is a block special file

For example:

Copy CodeThe code is as follows:
Cd/bin
If Test-e./bash
Then
Echo ' The file already exists! '
Else
Echo ' The file does not exists! '
Fi

Output:
The file already exists!

In addition, the shell provides three logical operators with (!), or (-O), non (-a) to connect test conditions, with the priority of: "!" Highest, "-a" followed, "-O" the lowest. For example:

Copy CodeThe code is as follows:
Cd/bin
If Test-e./notfile-o./bash
Then
Echo ' one file exists at least! '
Else
echo ' Both dose not exists! '
Fi

Output:
One file exists at least!

Use "Go" of the test command in Shelll