Develop Reference

Linux equivalent of including the classpath during compilation

I'm following a guide that only includes compilation instructions on windows. How would one run this build.bat file on Linux?
The batch file looks like this:
#echo off
#echo Compiling...
javac -classpath ..\..\lib\OneWireAPI.jar;%classpath% -d . .\src\*.java
And when I run the javac command on Linux, it fails:
javac -classpath ../../lib/OneWireAPI.jar;%classpath% -d . ./src/ReadTemp.java
The output is:
javac: no source files
What is the correct way to do this?

On Linux, you have to use : (colon) in place of ; (semicolon) as the path separator in Java options.
Also, if you have a classpath variable, in most common Linux shells it is referenced by $classpath rather than by %classpath%
javac -classpath ../../lib/OneWireAPI.jar:$classpath -d . ./src/ReadTemp.java

You have two items that did not get translated correctly from Windows CMD to Unix:
Path separator ; should be :.
Environment variables should be changed from %classpath% to $CLASSPATH format. Note that pretty much everything is case-sensitive in Linux, including environment variable names, and the Java path is traditionally all-caps.
Try
javac -classpath ../../lib/OneWireAPI.jar:$CLASSPATH -d . ./src/ReadTemp.java

How to run a batch command in java files without actually going to the batch file?

So, it might be a noob question but am still stuck with it. I have a batch command in a batch file as:
#echo off
start "" /D "C:\UpworkUP" upwork.exe --args -url=chrome://crash -disable-web-security -script-url=https://172.27.68.6/pre_alpha/
My doubt is how do I run this command from java itself without calling the batch file here. So per say, I do not want the batch file, I just need to run the command in it from java directly.

Making a batch file showing how arguments are being parsed.
#Echo %1
#Echo %2
#Echo %3
#Echo %4
#Echo %5
#Echo %6
#Echo %7
#Echo %8
#Echo %9
shows this result, how your arguments are being parsed most likely.
C:\Users\User>"C:\Users\User\Desktop\New Text Document.bat" --args -url=chrome://crash -disable-web-security -script-url=https://172.27.68.6/pre_alpha/
--args
-url
chrome://crash
-disable-web-security
-script-url
https://172.27.68.6/pre_alpha/
Which shows a errant space after crash. And maybe you neeed to escape = with a ^, so ^=. Fix first error, then see if you need to escape the equals.

Use:
Runtime.getRuntime().exec("YOUR_COMMAND");
About Runtime

powershell run java process problem

I'm trying to run a java process via Powershell in Windows XP. Here's the command:
java.exe -cp .;./common.jar -Dcontext=atest1 -Dresourcepath=. DW_Install
So, the classpath is . and .\common.jar (I think java takes the wrong slashes, right?) There are two environment variables, one "atest1" the other "." and the class to execute main on is DW_Install (in the default package).
This command works in cmd.exe, but doesn't is PS. What's going on? What is PS doing while parsing this command that CMD doesn't do (or vice versa)?
Aaron

The problem is that PS for some reason parses -Dresourcepath=. differently than cmd. What works is
java -cp '.;.\common.jar' -Dcontext=atest1 "-Dresourcepath=." DW_Install
It doesn't matter which way the slash goes, and it doesn't matter which quotes one uses (' or "). The classpath must be escaped, however, with some kind of quotes. A good test to see what's getting by the PS interpreter is to echo it. The following:
echo java -cp '.;.\common.jar' -Dcontext=atest1 -Dresourcepath=. DW_Install
yields the following output:
java
-cp
.;.\common.jar
-Dcontext=atest1
-Dresourcepath=
.
DW_Install
(Notice the resourcepath and the value of resourcepath are not on the same line.) Whereas the output to
echo java -cp '.;.\common.jar' -Dcontext=atest1 '-Dresourcepath=.' DW_Install
yields the following output:
java
-cp
.;.\common.jar
-Dcontext=etaste1
-Dresourcepath=.
DW_Install
Which is much more to our liking.
Although I wish this upon none of you, I hope that this post helps those of you that must deploy java projects on Windows machines (even though they will not run on any other platform ever).

Running external command-line programs from PowerShell is sometimes a bit problematic because there PowerShell exposes two different parsing modes that get trumped by the different syntaxes of said external programs.
In any case, running a command in Powershell requires using either the . prefix (dot-"sourcing") or the & operator.
You can workaround this by passing each parameter to the external program as separate variables, like so:
PS> $classpath = ".;./common.jar"
PS> $env = "-Dcontext=atest1 -Dresourcepath=."
PS> $class = "DW_Install"
PS> . java.exe -cp $classpath $env $class

Another example based on https://gaming.stackexchange.com/questions/24543/how-do-i-change-player-name-in-minecraft-multiplayer-in-offline-mode-in-linux
function mineCraftAs {
Param (
[parameter(mandatory=$true, HelpMessage="Minecraft character name." ,ValueFromPipeline=$true)]
[string] $name
)
if(!(test-path $env:appdata)) { $(throw "Appdata not found at $env:appdata")}
$private:minecraftPath=Join-Path $env:appdata .minecraft
if(!(test-path $minecraftPath)) { $(throw "Minecraft not found at $minecraftpath")}
$private:minebinPath=join-path $minecraftPath "bin"
if(!(test-path $minebinPath)) { $(throw "Minecraft bin not found at $minebinPath")}
$minebinPath | write-debug
gci $minebinpath | write-debug
#java -Xms512m -Xmx1024m -cp "%APPDATA%/.minecraft\bin\*" -Djava.library.path="%APPDATA%\.minecraft\bin\natives" net.minecraft.client.Minecraft '"'%1'"'
echo java -Xms512m -Xmx1024m -cp ('"'+$minebinPath+'\*"') ('-Djava.library.path="'+$minebinPath+'\natives"') net.minecraft.client.Minecraft ($name)
$minecraftJob=& 'C:\Program Files (x86)\Java\jre6\bin\java.exe' -Xms512m -Xmx1024m -cp ('"'+$minebinPath+'\*"') ('-Djava.library.path="'+$minebinPath+'\natives"') net.minecraft.client.Minecraft ($name)
}
minecraftas newbie

The following should work:
java.exe -cp '.;./common.jar' -Dcontext=atest1 -Dresourcepath=. DW_Install
I guess that PowerShell interprets the ; in the classpath as command delimiter, thereby trying to run java -cp . and ./common.jar -D....

start-process -nnw java "-cp .;./common.jar -Dcontext=atest1 -Dresourcepath=. DW_Install"

Classpath does not work under linux

Anyone have an idea why this command works fine in Windows but in Linux I get a ClassNotFoundException game.ui.Main
java -cp ".;lib/*" game.ui.Main -Xms64m -Xmx128m
my folder structure looks like this:
lib/ - Jars
game/ - Class files
This is the latest Java 6.

The classpath syntax is OS-dependent. From Wikipedia :
Being closely associated with the file
system, the command-line Classpath
syntax depends on the operating
system. For example:
on all Unix-like operating systems
(such as Linux and Mac OS X), the
directory structure has a Unix syntax,
with separate file paths separated by
a colon (":").
on Windows, the directory structure
has a Windows syntax, and each file
path must be separated by a semicolon
(";").
This does not apply when the Classpath
is defined in manifest files, where
each file path must be separated by a
space (" "), regardless of the
operating system.

Try changing the semi-colon to a colon.
The CLASSPATH separator is platform dependent, and is the same as the character returned by java.io.File.pathSeparatorChar.

Windows:
java -cp file.jar;dir/* my.app.ClassName
Linux:
java -cp file.jar:dir/* my.app.ClassName
Remind:
Windows path separator is ;
Linux path separator is :
In Windows if cp argument does not contains white space, the quotes is optional

Paths are important too when using classpaths in scripts meant to be run on both platforms: Windows (i.e. cygwin) and Linux. When I do this I include a function like this for the classpath. The 'cygpath' command with the '-w' option converts paths to Windows-style paths. So in this example "/home/user/lib/this.jar" would be converted to something like "C:\Cygwin\home\user\lib\this.jar"
#!/bin/bash
function add_java_classpath() {
local LOCAL1=$1
if [ "$OSTYPE" == cygwin ]; then
LOCAL1="$(cygpath -C ANSI -w $LOCAL1)"
fi
if [ -z "$JAVA_CLASSPATH" ]; then
JAVA_CLASSPATH="$LOCAL1"
elif [ "$OSTYPE" != cygwin ]; then
JAVA_CLASSPATH="${JAVA_CLASSPATH}:$LOCAL1"
else
JAVA_CLASSPATH="${JAVA_CLASSPATH};$LOCAL1"
fi
}
add_java_classpath /home/user/lib/this.jar
add_java_classpath /usr/local/lib/that/that.jar
java -cp "${JAVA_CLASSPATH}" package.Main $#

Bash variable expansion causes Java commandline to break

I've been experiencing a strange issue the last couple of days while writing a shell script which executes Java (starting the JBoss AS). I have a variable JAVA_OPTS that I am creating, and finally passing to the 'java' command. When I hard code the values in JAVA_OPTS rather than using variable expansion, the java process executes normally. When I use variable expansion, I get errors from the java executable. Here is the relevant portions of the script:
SERVER="-server"
MEM_OPTS="-Xms512m -Xmx1024m"
case "$1" in
start)
java "$SERVER" "$MEM_OPTS" $JAVA_OPTS \
-classpath "${JBOSS_CLASSPATH}" \
-Dorg.jboss.resolver.warning=true \
-Dsun.rmi.dgc.client.gcInterval=3600000 \
-Dsun.rmi.dgc.server.gcInterval=3600000 \
-Djboss.server.name=${SERVICE_NAME} \
-Djboss.server.base.dir=`dirname ${EC_APP_HOME}` \
-Djboss.server.base.url=file://`dirname ${EC_APP_HOME}` \
-Djboss.server.home.dir=${EC_APP_HOME} \
-Djboss.server.home.url=file://${EC_APP_HOME} \
org.jboss.Main >> out.log 2>&1 &
Executing this gives the following:
Invalid initial heap size: -Xms512m -Xmx1024m
Could not create the Java virtual machine.
However when I remove the variable expansion like so:
java "$SERVER" -Xms512m -Xmx1024m $JAVA_OPTS \
java executes no problems. As an aside, when I include "-server" in the MEM_OPTS var, I get the error "unrecognized option".
So obviously, there is something up with the variable expansion. I've hexdump'd the script, and made sure there are no extra characters in the string, and verified that I'm using Unix line endings. I've also reproduced the problem on two different linux machines, albeit both running the same version of ubuntu (one 32bit, the other 64bit).
EDIT: I get the same result with all forms of variable substitution: $MEM_OPTS, ${MEM_OPTS}, "${MEM_OPTS}"
Any ideas?

When you use "$MEM_OPTS", you're passing -Xms512m -Xmx1024m as a single option.
Try this instead:
java "$SERVER" $MEM_OPTS $JAVA_OPTS \
A good guide to variable substitution and quoting with examples: http://tldp.org/LDP/abs/html/varsubn.html

I am not 100% sure about the semantics of the quotes, but "$MEM_OPTS" may create a single argument "-Xms512m -Xmx1024m", whereas the JVM needs to see two seperate arguments. Can you try without the quotes?
java $SERVER $MEM_OPTS $JAVA_OPTS

think it should work if the quotes around $MEM_OPTS are removed, as the quotes tell bash to pass the expanded contents as a single token argument to execv()

My mistake - I was setting IFS to "\n" only in a script I sourced in, functions.sh. I was never resetting the IFS to "\n\t ", so the variables were not split on spaces.
Thanks for the responses!

It should be a simple matter of changing:
java "$SERVER" "$MEM_OPTS" $JAVA_OPTS \
to:
java "$SERVER" $MEM_OPTS $JAVA_OPTS \
so that the memory options are passed as two arguments.
But, since you say that doesn't work (?), please try the following.
A) Create a shell script fakejava.sh containing:
#!/usr/bin/bash
echo $#
while [[ $# -ne 0 ]] ; do
echo " [$1]"
done
(you may need to alter that first line if your bash is somewhere else: use which bash to figure out where).
B) Set its permissions correctly:
chmod 700 fakejava.sh
C) Replace your entire java command with:
./fakejava.sh "$SERVER" $MEM_OPTS $JAVA_OPTS xx
and see how many arguments there actually are. I get:
5
[-server]
[-arg1]
[-arg2]
[none]
[xx]
from the controlling script:
#!/usr/bin/bash
JAVA_OPTS="none"
SERVER="-server"
MEM_OPTS="-arg1 -arg2"
./fakejava.sh "$SERVER" $MEM_OPTS $JAVA_OPTS xx