Shell Script Test command uses summary and instance _linux shell

The test command in the shell is used to check whether a condition is valid, and it can be tested in three aspects, such as numeric value, character, and file.

Numerical test

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

For example:

Copy Code code as follows:

num1=100
num2=100
if test $[num1]-eq $[num2]
Then
Echo ' The two numbers are equal! '
Else
Echo ' The two numbers are not equal! '
Fi

Output:
The two numbers are equal!

String test

Parameters	Description
=	is equal to True
!=	Not Equal is true
-Z String	String length pseudo is True
-N String	String length not False is true

For example:

Copy Code code as follows:

num1=100
num2=100
if test num1=num2
Then
Echo ' The two strings are equal! '
Else
Echo ' The two strings are not equal! '
Fi

Output:
The two strings are 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 filename	True if the file exists and is executable
-S filename	If the file exists and at least one character is true
-D file name	True if the file exists and is a directory
-F filename	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 filename	True if the file exists and is a block-specific file

For example:

Copy Code code 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 a (!), or (-O), non (-a) three logical operators to connect test conditions with a priority of: "!" Highest, "-a" second, "-O" lowest. For example:

Copy Code code 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!