Shell---"Test command set

Shell Test Command

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

Example Demo:

NUM1=num2= +if test $[num1]-eq $[num2] then' two numbers equal! 'else' two numbers are not equal! 'fi                   

Output Result:

Two numbers equal!

The [] in the code performs the basic arithmetic operations, such as:

#!/bin/basha=5b=6Result=$[a+b]# Note There must be no spaces on either side of the equals sign "result is: $result"               

The result is:

is: One

String test

Parameters	Description
=	Equals is True
!=	Not Equal is true
-Z String	True if the length of the string is zero
-N String	True if the length of the string is nonzero

Example Demo:

NUM1="Ru1noob"num2= "runoob"if= $num 2then' two strings equal! ' else' two strings are not equal! ' fi            

Output Result:

Two strings are not 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

Example Demo:

/Binif-./bashthen' file already exists! ' else' file does not exist! ' fi         

Output Result:

File already exists!

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

/Binif-./--./bashthen' There is a file present! ' else' two files do not exist 'fi            

Output Result:

There is a file present!

Shell---"Test command set