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Java - How to print OS / system environment variables?
1 points
In java we can use System.getenv() to get a Map with all current system environment variables.
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// fast way to print all environment variables2
Map<String, String> env = System.getenv();3
env.forEach((key, value) -> System.out.println(key + " : " + value));xxxxxxxxxx1
import java.util.Map;2
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public class JavaPrintSystemEnvironmentVariables {4
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public static void main(String[] args) {6
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Map<String, String> env = System.getenv();8
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for (Map.Entry<String, String> entry : env.entrySet()) {10
String key = entry.getKey();11
String value = entry.getValue();12
13
System.out.println(key + " : " + value);14
}15
}16
}Output:
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PROCESSOR_LEVEL : 62
FPS_BROWSER_APP_PROFILE_STRING : Internet Explorer3
LOGONSERVER : \\DESKTOP-MMNVSIU4
SESSIONNAME : Console5
ALLUSERSPROFILE : C:\ProgramData6
PROCESSOR_ARCHITECTURE : AMD647
SystemDrive : C:8
USERNAME : seth9
OS : Windows_NT10
NUMBER_OF_PROCESSORS : 411
windir : C:\Windows12
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...This this output of some of the system environment variables.
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import java.util.Map;2
3
public class JavaPrintSystemEnvironmentVariablesJava8 {4
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public static void main(String[] args) {6
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Map<String, String> env = System.getenv();8
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env.forEach((key, value) -> System.out.println(key + " : " + value));10
}11
}Output:
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PROCESSOR_LEVEL : 62
FPS_BROWSER_APP_PROFILE_STRING : Internet Explorer3
LOGONSERVER : \\DESKTOP-MMNVSIU4
SESSIONNAME : Console5
ALLUSERSPROFILE : C:\ProgramData6
PROCESSOR_ARCHITECTURE : AMD647
SystemDrive : C:8
USERNAME : seth9
OS : Windows_NT10
NUMBER_OF_PROCESSORS : 411
windir : C:\Windows12
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...This this output of some of the system environment variables.
This example will print all system environment variables in alphabetical order from A to Z.
To keep the order of keys we use TreeSet<String> and String class has default comparator.
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import java.util.Map;2
import java.util.SortedSet;3
import java.util.TreeSet;4
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public class JavaPrintSystemEnvironmentVariablesSorted {6
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public static void main(String[] args) {8
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Map<String, String> env = System.getenv();10
SortedSet<String> keys = new TreeSet<>(env.keySet());11
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for (String key : keys) {13
String value = env.get(key);14
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System.out.println(key + " : " + value);16
}17
}18
}Output:
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=:: : ::\2
ALLUSERSPROFILE : C:\ProgramData3
APPDATA : C:\Users\seth\AppData\Roaming4
COMPUTERNAME : DESKTOP-MMNVSIU5
ComSpec : C:\Windows\system32\cmd.exe6
CommonProgramFiles : C:\Program Files\Common Files7
CommonProgramFiles(x86) : C:\Program Files (x86)\Common Files8
CommonProgramW6432 : C:\Program Files\Common Files9
DriverData : C:\Windows\System32\Drivers\DriverData10
FPS_BROWSER_APP_PROFILE_STRING : Internet Explorer11
FPS_BROWSER_USER_PROFILE_STRING : Default12
HOMEDRIVE : C:13
HOMEPATH : \Users\seth14
LOCALAPPDATA : C:\Users\seth\AppData\Local15
LOGONSERVER : \\DESKTOP-MMNVSIU16
MOZ_PLUGIN_PATH : C:\Program Files\Tracker Software\PDF Viewer\Win32\17
NUMBER_OF_PROCESSORS : 418
OS : Windows_NT19
OneDrive : C:\Users\seth\OneDrive20
OneDriveConsumer : C:\Users\seth\OneDrive21
PATHEXT : .COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC22
PROCESSOR_ARCHITECTURE : AMD6423
PROCESSOR_IDENTIFIER : Intel64 Family 6 Model 60 Stepping 3, GenuineIntel24
PROCESSOR_LEVEL : 625
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...xxxxxxxxxx1
import java.util.Map;2
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public class JavaGetSingleEnvironmentVariablesExample {4
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public static void main(String[] args) {6
Map<String, String> env = System.getenv();7
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String os = env.get("OS");9
System.out.println(os); // Windows_NT10
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String username = env.get("USERNAME");12
System.out.println(username); // seth13
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String numberOfProcessors = env.get("NUMBER_OF_PROCESSORS");15
System.out.println(numberOfProcessors); // 416
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String systemDrive = env.get("SystemDrive");18
System.out.println(systemDrive); // C:19
}20
}Output:
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Windows_NT2
seth3
44
C:In above examples we used System.getenv().
What this method really do?
Syntax:
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public static Map<String,String> getenv()From java docs:
Returns an unmodifiable string map view of the current system environment.
The environment is a system-dependent mapping from names to values which is passed from parent to child processes.
If the system does not support environment variables, an empty map is returned.
Returns:
the environment as a map of variable names to values
