CODEWITHSUNDEEP
macosbash
Technic1an
Technic1an

Reputation: 2797

Bash string comparison of two identical strings false?

Hello I have the following script:

#! /bin/bash
 Output=$(defaults read com.apple.systemuiserver menuExtras | grep Bluetooth.menu)
Check="\"/System/Library/CoreServices/Menu Extras/Bluetooth.menu\","
echo $Output
echo $Check
     if [ "$Output" = "$Check" ]
    then
           echo "OK"
else
    echo "FALSE" 
    echo "Security Compliance Setting 'Show Bluetooth Status in Menu Bar(2.1.3)' has been changed!" | logger

fi

When you run it, both variables have the exact same output however the check always says it is FALSE

here is the out put from my terminal:

"/System/Library/CoreServices/Menu Extras/Bluetooth.menu",
"/System/Library/CoreServices/Menu Extras/Bluetooth.menu",
FALSE

Any idea why it is not detecting that they are the same?

Upvotes: 0

Views: 305

Answers (1)

Gordon Davisson
Gordon Davisson

Reputation: 125838

As everyone in the comments suspected, the problem is whitespace in $Output (which echo $Output removes); specifically, 4 leading spaces (note that in the following, "$ " is my shell prompt):

$ defaults read com.apple.systemuiserver menuExtras | grep Bluetooth.menu
    "/System/Library/CoreServices/Menu Extras/Bluetooth.menu",
$ Output=$(defaults read com.apple.systemuiserver menuExtras | grep Bluetooth.menu)
$ echo $Output
"/System/Library/CoreServices/Menu Extras/Bluetooth.menu",
$ echo "[$Output]"
[    "/System/Library/CoreServices/Menu Extras/Bluetooth.menu",]
$ Check="    \"/System/Library/CoreServices/Menu Extras/Bluetooth.menu\","
$ if [ "$Output" = "$Check" ]; then echo "OK"; else echo "FALSE"; fi
OK

Note that since the number of spaces might not always be the same, it might be safer to use bash's wildcard matching capability within a [[ ]] conditional expression (this will not work with [ ]):

$ Check="\"/System/Library/CoreServices/Menu Extras/Bluetooth.menu\","
$ if [[ "$Output" = *"$Check" ]]; then echo "OK"; else echo "FALSE"; fi
OK

You could also skip the string comparison entirely, and just use the fact that grep returns a success status only if it finds a match:

#!/bin/bash
if defaults read com.apple.systemuiserver menuExtras | grep -q "/System/Library/CoreServices/Menu Extras/Bluetooth.menu"; then
    echo "OK"
else
    echo "FALSE" 
    echo "Security Compliance Setting 'Show Bluetooth Status in Menu Bar(2.1.3)' has been changed!" | logger
fi

Upvotes: 1

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