Read environment variables from file in Windows Batch (cmd.exe)

Question

I'm trying to read variables from a batch file for later use in the batch script, which is a Java launcher. I'd ideally like to have the same format for the settings file on all platforms (Unix, Windows), and also be a valid Java Properties file. That is, it should look like this:

setting1=Value1
setting2=Value2
...

Is it possible to read such values like you would in a Unix shell script? The could should look something like this:

READ settingsfile.xy
java -Dsetting1=%setting1% ...

I know that this is probably possible with SET setting1=Value1, but I'd really rather have the same file format for the settings on all platforms.

To clarify: I need to do this in the command line/batch environment as I also need to set parameters that cannot be altered from within the JVM, like -Xmx or -classpath.

to StackOverflow · Accepted Answer · 2008-10-24 08:17:30Z

45

You can do this in a batch file as follows:

setlocal
FOR /F "tokens=*" %%i in ('type Settings.txt') do SET %%i
java -Dsetting1=%setting1% ...
endlocal

This reads a text file containing strings like "SETTING1=VALUE1" and calls SET to set them as environment variables.

setlocal/endlocal are used to limit the scope of the environment variables to the execution of your batch file.

The CMD Command Processor is actually quite powerful, though with a rather byzantine syntax.

answered Oct 24, 2008 at 8:17

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4 Comments

Pereira Over a year ago

After a long time looking for a solution, I found this solution. Thank you!

malthe Over a year ago

How would you ignore a "comment" (for example, a line starting with a "#" character) - ?

to StackOverflow Over a year ago

@malthe - one way is just to ignore any error messages the comment lines produce, or hide them thus FOR /F "tokens=*" %%i in ('type Settings.txt') do SET %%i 2> NUL:

shurkam Over a year ago

@malthe - Add eol=<comment character>. FOR /F "tokens=* eol=#" %%i in ('type Settings.txt') do SET %%i

Winand · Accepted Answer · 2023-02-22 15:54:00Z

4

This one-liner also unquotes value before assigning it to a variable:

for /F "delims== tokens=1,* eol=#" %%i in (%filename%) do set %%i=%%~j

delims== split lines by = character
tokens=1,* put first token (name) into %%i and the rest (value) into %%j
eol=# skip lines starting with # (comments)
%%~j remove surrounding quotes from value

answered Feb 22, 2023 at 15:54

Winand

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Comments

Eboubaker · Accepted Answer · 2024-06-05 11:08:23Z

3

FOR /F "eol=# tokens=*" %%i IN (%~dp0.env) DO SET %%i

It will only work in .bat file (not cmd.exe)

This will do the following:

Skips all lines that start with # (can be used for comments)
Reads the file .env which sits in the same directory of the batch script and pass the lines to SET

To be more helpful This is the .env file i was parsing

# The name of the mariadb service to be installed
MariaDb_serviceName=Swoole_MariaDB
# which port the mariadb server will run at
MariaDb_port=1214
# password of mariadb root user
MariaDb_rootPassword=
# Database to be created after installing mariadb
MariaDb_createDataBase=data
# the server service name to be installed
Server_serviceName=Swoole_Server

edited Jun 5, 2024 at 11:08

answered Dec 23, 2021 at 20:20

Eboubaker

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2 Comments

Stephan Over a year ago

No need for /a, as batch knows about only one variable type anyway: STRING. set /a is used to translate strings into integers to do arithmetic and assigns again a string to the variable.

Eboubaker Over a year ago

@Stephan I have modified the answer, I did not know about it thank you!

call me Steve · Accepted Answer · 2008-10-24 22:26:05Z

2

You can pass the property file as a parameter to a Java program (that may launch the main program later on). And then benefit from the multi platform paradigm.

edited Oct 24, 2008 at 22:26

answered Oct 24, 2008 at 7:56

call me Steve

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2 Comments

Martin Probst Over a year ago

Yes, that's generally true, but I need to configure stuff like -Xmx too, which of course cannot be changed once the JVM is running.

call me Steve Over a year ago

Oh I see, it's sounds overkill compare to the solutions but you may re-launch the Java from another Java. Don't get my wrong I do prefer the selected solution.

Jared · Accepted Answer · 2011-06-02 13:40:32Z

1

It may be wise to only import specific variables from a properties file (ones you know about ahead of time), in that case I recommend a function like the following:

:parsePropertiesFile
    set PROPS_FILE=%1
    shift
    :propLoop
    if "%1"=="" goto:eof
    FOR /F "tokens=*" %%i in ('type %PROPS_FILE% ^| findStr.exe "%1="') do SET %%i
    shift
    GOTO propLoop
goto:eof

Which would be called by call:parsePropertiesFile props.properties setting1 setting2 to set the variables setting1 and setting2

edited Jun 2, 2011 at 13:40

answered Jun 1, 2011 at 16:23

Jared

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Comments

micro · Accepted Answer · 2008-10-24 22:55:52Z

0

You can also access the OS' environment variables from within a Java program:

import java.util.Map;

public class EnvMap {
    public static void main (String[] args) {
        Map<String, String> env = System.getenv();
        for (String envName : env.keySet()) {
            System.out.format("%s=%s%n", envName, env.get(envName));
        }
    }
}

answered Oct 24, 2008 at 22:55

micro

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