Shell Test Command

Source: Internet
Author: User
Tags logical operators

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+"result is: $ Result"

The 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    ' 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:

CD/binif test-e./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:

CD/binif test-e./notfile-o-E./    bashthen' has a file present! ' Else    ' None of the two files exist ' fi     

Output Result:

There is a file present!

Shell Test Command

Related Article

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.