Develop Reference

How to tell whether current bash script was invoked from call script

I have a script that ideally will be used in two different ways. One, run stand-alone from command line. Two invoke from a service script located in /etc/init.d.
I would like the script (call it run_app.sh) to work as follows:
#/bin/bash
# this is run_app.sh. It should be able to be run stand-alone or called from another script
if [ invoked by a calling script ] then
java -cp . -jar blah.jar
else
nohup java -cp . -jar blah.jar 2>&1 &
, so its the "invoked by a calling script" that I would need help with. Thank you.

If you plan to launch your script either by issuing ./run_app.sh or the service. You can just use $0:
#!/bin/bash
# this is run_app.sh. It should be able to be run stand-alone or called from another script
this_script_name="run_app.sh"
if [ "$0" == "./${this_script_name}" ] then
java -cp . -jar blah.jar
else
nohup java -cp . -jar blah.jar 2>&1 &

Instead of trying to find out how the script was called, I suggest to use a command line argument.
Script app.sh
#/bin/bash
# this is run_app.sh. It should be able to be run stand-alone or called from another script
if [ "$1" = "--service" ] then
java -cp . -jar blah.jar
else
nohup java -cp . -jar blah.jar 2>&1 &
fi
Manually run the script as app.sh, from the calling script run app.sh --service.
If you need to pass additional command line arguments to your script, you might have to implement some better option parsing.
Note: Checking $0 may work under certain conditions, but may not work in some other cases. Trying to find out details about the parent processes is even more difficult and fragile.
Another note: Your java command line arguments -cp . -jar blah.jar depend on the current directory. To make sure this works in all cases, the script should cd into the correct directory before calling java. e.g. cd $(dirname "$0") if the script is located in the same directory as blah.jar.

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

Running jar via code- Java

final String dir = "C:\\Users\\theo\\Desktop\\1.6 test\\craftbukkit.jar";
Process proc = Runtime.getRuntime()
.exec("java -Xmx1024M -jar "+ dir +" -o true PAUSE");
So.I did some research around here but this thing apparently is not working/running the JAR file.

Note the space in the path of the jar. This means, in the command you build up it will be seen as two arguments:
java -Xmx1024M -jar C:\Users\theo\Desktop\1.6 test\craftbukkit.jar -o true PAUSE
Try to quote the path to build a command like this:
java -Xmx1024M -jar "C:\Users\theo\Desktop\1.6 test\craftbukkit.jar" -o true PAUSE

You need to provide the full path to the Java executable, not just 'java'.
Assuming the program in question is well-behaved, you could use reflection to invoke the main method on the jar's main class without starting up a new JVM.

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"

Calling java program dependent on external library

I am trying to call a java program in php to use it with web interface.
Java program is dependent on an external lib: commons-cli-1.2.jar
So basically I need to export it before calling the java program; but if I export it first as:
shell_exec('export CLASSPATH=$CLASSPATH:~/lib/commons-cli-1.2.jar');
then call the java program as:
shell_exec('java ComputePagerank -i $para_i -d $para_d -e $para_e -o $para_o');
I think it creates different shells for each call; then the export does not have any effect on java program. Or am I wrong?
Otherwise, it should output a file in the server. But simply it does not. So, what is wrong? Any idea?
edit: However can it be because some parameters such as para_i stands for an input file name, so that i have to specify full path for that? Because I just assume if the input file is in the same working directory, there won't be any problem, will it?
edit-2: it outputs properly when i use command line;)

you're right, each shell_exec creates a separate shell.
env CLASSPATH=whatever java -switches

I would use
shell_exec('java -cp $CLASSPATH:/home/yourname/dir/lib/commons-cli-1.2.jar ComputePagerank -i $para_i -d $para_d -e $para_e -o $para_o > message');
and (this is important) replace the tilde(~) with the actual path to your directory (/home/yourname say). The ~ is expanded by the shell and is dependent on which shell you''re using.

Try Creating a simple shell script with the commands that you want to execute. You may pass arguments to a shell script so that is not a problem either.
for example
echo "Running Script..."
java -cp $CLASSPATH:~/lib/commons-cli-1.2.jar ComputePagerank -i $1 -d $2 -e $3 -o $4 > message
etc.
Then try calling it from the command line first with some parameters. Did it output? Then try calling it from the php script. Did it output? If it did not then you may need to check permissions. I had a simiolar experience some time ago with a Java program that simply did not have permission to write a file.

You should be able to call it like this.
shell_exec('java -cp $CLASSPATH:~/lib/commons-cli-1.2.jar ComputePagerank -i $para_i -d $para_d -e $para_e -o $para_o > message');
Another option is to issue the 2 commands seperately, but to the same shell, like this:
shell_exec('export CLASSPATH=$CLASSPATH:~/lib/commons-cli-1.2.jar; java ComputePagerank -i $para_i -d $para_d -e $para_e -o $para_o > message');
edit:
some shells don't let you call export while you're setting up the variable. so this may be safer than the second option above:
shell_exec('CLASSPATH=$CLASSPATH:~/lib/commons-cli-1.2.jar; export CLASSPATH; java ComputePagerank -i $para_i -d $para_d -e $para_e -o $para_o > message');
another edit:
If none of the above work then you're going to have to do some more trouble shooting. Does your java program work from the command prompt?
java -cp $CLASSPATH:/home/user/lib/commons-cli-1.2.jar ComputePagerank -i param1 -d param2 -e param3 -o param4 > message