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

Parameter description

-eq equals True

-ne is not equal to true

-GT is greater than true

-ge is true if it is greater than or equal

-lt is less than true

-le is less than or equal to true

Example Demo:

num1=100

num2=100

if test $[num1]-eq $[num2]

Then

Echo ' Two numbers equal! ‘

Else

Echo ' Two numbers not equal '

Fi

Output Result:

Two numbers equal!

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

#!/bin/bash

A=5

B=6

RESULT=$[A+B] # Note that there must be no spaces on either side

echo "Result: $result"

The result is:

Result is: 11

String test

Parameter description

= Equals is True

！ = True if not equal

-Z String string is true if the length is zero

-N String string is true if the length is nonzero

Example Demo:

num1= "Rulnoob"

Num2= "Runoob"

if test $num 1 = $num 2

Then

Echo ' Two strings equal! '

Else

Echo ' two strings are not equal! '

Fi

Output Result:

Two strings are not equal!

File test

Parameter description

-e filename stating that the file exists is true

-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 if file exists and executable is true

-d file name if the file exists and is true for the directory

-f filename If the file exists and is a character special file is True

-B file name True if file exists and is a block special file

Example Demo:

Cd/bin

If Test-e./bash

Then

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 link test conditions, with the priority being:! Highest-a second-o lowest

Shell Test Command