shell--7, 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=100num2=100if Test $[NUM1]-eq $[num2]then echo ' two numbers equal! ' Else echo ' 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 that there is no space on either side of the equal sign echo "Result: $result"

The result is:

Result is: 11

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 test $num 1 = $num 2then echo ' two strings equal! ' else echo ' 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:

Cd/binif test-e./bashthen echo ' file already exists! ' else echo ' 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:

Cd/binif test-e./notfile-o-E./bashthen echo ' has a file present! ' else echo ' Two files do not exist ' fi

Output Result:

There is a file present!

This article is from the "Wind Trace _ Snow Tiger" blog, please be sure to keep this source http://snowtiger.blog.51cto.com/12931578/1941356

Shell--7, Shell Test command