The correct method for determining null strings in Linux Shell

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Help Test

 

Correct practice:

 

#! /Bin/sh

String =

If [-z "$ string"]; then
Echo "string is empty"
Fi

If [-n "$ string"]; then
Echo "string is not empty"
Fi

 

Root @ James-desktop :~ #./Zerostring. Sh
String is empty

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Incorrect practice:

#! /Bin/sh

String =

If [-Z $ string]; then
Echo "string is empty"
Fi

If [-N $ string]; then
Echo "string is not empty"
Fi

Output Error result:

Root @ James-desktop :~ #./Zerostring. Sh
String is empty
String is not empty