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Java Forum / General / June 2005wildcards
I just discovered something odd. EVERY Java utility has wildcard ability on the command line. If you write *.* as a parameter, you don't see "*.*" appearing in args[0]. Instead you see a list of all the filenames and directory names in the current directory, one per argument. Is this new? Who is doing this? Windows, 4NT, Java? if you write *.* as a parameter, you will get a list of all files and directories in the current directory beginning with a. But if you type . you just get the . This mechanism only seems to kick in when you use a wildcard ? or *. It is somewhat dangerous. *.* for a utility not prepared for it. *.* does a directory 1-deep recursion.  SignatureBush crime family lost/embezzled $3 trillion from Pentagon. Complicit Bush-friendly media keeps mum. Rumsfeld confesses on video. http://www.infowars.com/articles/us/mckinney_grills_rumsfeld.htm Canadian Mind Products, Roedy Green. See http://mindprod.com/iraq.html photos of Bush's war crimes > If you write *.* as a parameter, you don't see "*.*" appearing in > args[0]. Instead you see a list of all the filenames and directory > names in the current directory, one per argument. > > Is this new? Who is doing this? Windows, 4NT, Java? If you're doing at the command line, then I would bet the operating system is evaluating the "*.*" before passing it as an argument to 'java'. SignatureWendy Smoak It's nothing to do with java. It's solely due to the command line behavior. The console interprets the *.* as - all the files in current directory. So the java program receives the list of all the file names in ur directory. >>If you write *.* as a parameter, you don't see "*.*" appearing in >>args[0]. Instead you see a list of all the filenames and directory [quoted text clipped - 4 lines] > If you're doing at the command line, then I would bet the operating system > is evaluating the "*.*" before passing it as an argument to 'java'. I'm sure Roedy is aware of command line expansion. In any case, I just did some tests, and there is something else going on. For example, using Cygwin's bash, the line: echo '*' echoes an asterisk, so single quotes suppress the expansion, as they should in bash. On the other hand, in the same shell: java Echo '*' gets a directory listing, where Echo is a program that prints its arguments. So far, I have been unable to pass an asterisk to my program, which seems unfortunate. If I decorate it enough to prevent expansion, the decoration gets passed through as part of the argument. For example '"*"' is passed as "*" (three characters). I've checked the documentation for "java", and it does not describe this behavior. Patricia > >>If you write *.* as a parameter, you don't see "*.*" appearing in > >>args[0]. Instead you see a list of all the filenames and directory [quoted text clipped - 28 lines] > > Patricia For what it's worth I don't see the behavior you describe with Bash under Linux: jc@sarah:~/tmp$ echo $BASH_VERSION 3.00.14(1)-release jc@sarah:~/tmp$ cat Echo.java public class Echo { public static void main(String [] asArgs) { for(int nArg=0; nArg<asArgs.length; ++nArg) { System.out.println(nArg + ". '" + asArgs[nArg] + "'") ; } } } jc@sarah:~/tmp$ /usr/java/jdk1.5.0_01/bin/java Echo '*' 0. '*' jc@sarah:~/tmp$ /usr/java/jdk1.5.0_01/bin/java Echo \* 0. '*' jc@sarah:~/tmp$ /usr/java/jdk1.5.0_01/bin/java Echo "\*" 0. '\*' jc@sarah:~/tmp$ /usr/java/jdk1.5.0_01/bin/java Echo * 0. 'abstract-test' 1. 'aide-0.10' 2. 'audacity-src-1.2.3' 3. 'axis-1_2' etc. In widows console u can send * to the java program using "*". public class ArgsPrinter{ public static void main(String args[]){ System.out.println("Number of Arguments: " + args.length); for(int i=0;i<args.length; i++){ System.out.println(args[i]); } } } Just try to run the program as; run ArgsPrinter "*" result: Number of Arguments: 1 * - So you can input *. > For what it's worth I don't see the behavior you describe with Bash > under Linux: That is because the java program on Unix does not do command-line expansion. It -- correctly -- expects the invoking command processor to do whatever expansion is required. Under Windows (as under DOS) the architecture is different (and /very/ stupid, IMO): individual commands are expected to do their own expansion. That means that the Windows version of the java program is expanding the wildcard according to whatever rules are compiled into it, and there is nothing that the command processor (the cygwin version of bash in Patricia's example) can do about it. Command-line processing under Windows is, and always has been, utterly broken. -- chris >>>If you write *.* as a parameter, you don't see "*.*" appearing in >>>args[0]. Instead you see a list of all the filenames and directory [quoted text clipped - 29 lines] > > Patricia [sean@se2 tmp]$ cat e.java public class e { public static void main (String args[]){ System.out.println(args[0]); } } [sean@se2 tmp]$ java e \* * [sean@se2 tmp]$ java e \*.\* *.* SignatureSean One has to look out for engineers - they begin with sewing machines and end up with the atomic bomb. --Marcel Pagnol > I'm sure Roedy is aware of command line expansion. In any case, I just > did some tests, and there is something else going on. For example, using [quoted text clipped - 10 lines] > > gets a directory listing, where Echo is a program that prints its Is the program called `java' under cygwin a wrapper script which gets its argument passing to the real program all messed up? Harald. Signature---------------------+--------------------------------------------- Harald Kirsch (@home)| Java Text Crunching: http://www.ebi.ac.uk/Rebholz-srv/whatizit/software >>I'm sure Roedy is aware of command line expansion. In any case, I just >>did some tests, and there is something else going on. For example, using [quoted text clipped - 13 lines] > Is the program called `java' under cygwin a wrapper script which gets > its argument passing to the real program all messed up? Good question, but it doesn't seem to be: [510] which java /cygdrive/c/Program Files/Java/jdk1.5.0/bin/java /cygdrive/c is the unix-like path Cygwin gives to C:, so that is C:/Program Files/Java/jdk1.5.0/bin/java, my JDK1.5 java.exe. I also tested, before posting, with 1.4 by forcing the java.exe file name, and it behaved the same way. Patricia It seems to have something to do with bash, but I wonder what. The results are different on Windows command interpreter and on cygwin bash: C:\java>java Echo * 0. 'ant' 1. 'Echo.class' 2. 'Echo.java' 3. 'Echo.java~' 4. 'game' 5. 'test' C:\java>java Echo '*' 0. ''*'' C:\java>java Echo "*" 0. '*' >I'm sure Roedy is aware of command line expansion. I wasn't until I did some experiments. I wrote a little essay, as usual on what I found out about command line expansion. see http://mindprod.com/jgloss/wildcard.html SignatureBush crime family lost/embezzled $3 trillion from Pentagon. Complicit Bush-friendly media keeps mum. Rumsfeld confesses on video. http://www.infowars.com/articles/us/mckinney_grills_rumsfeld.htm Canadian Mind Products, Roedy Green. See http://mindprod.com/iraq.html photos of Bush's war crimes >>I'm sure Roedy is aware of command line expansion. > > I wasn't until I did some experiments. I wrote a little essay, as > usual on what I found out about command line expansion. > > see http://mindprod.com/jgloss/wildcard.html Roedy, Portions of the essay are somewhat misleading. In Windows, it is not the command interpreter or BAT language that expands the wildcards. It is the application that is invoked that does the expanding. This explains why wildcard expansion in Windows can be inconsistent from program to program. I am confused by one part of your essay: - Oddly if you pass a wild card to any Java utility, the command - processor expands the wildcards so that you program for *.* will see - list of all the directories and all the files, one per arg[i] slot. Unless the directories have the a period character in the name, they should not match the *.* wildcard expression. If this does happen perhaps you have found a bug in the JVM. HTH, Ray SignatureXML is the programmer's duct tape. >>> I'm sure Roedy is aware of command line expansion. >> [quoted text clipped - 23 lines] > HTH, > Ray Hi, At least in old DOS, *.* actually meant every file, whether or not it contained a dot. This would be because every file "implicitly" had a dot in it. Meanwhile, just asking for * I think didn't match anything. Chris >Portions of the essay are somewhat misleading. In Windows, it is not >the command interpreter or BAT language that expands the wildcards. It [quoted text clipped - 11 lines] >should not match the *.* wildcard expression. If this does happen >perhaps you have found a bug in the JVM. try this out. I think you will be surprised. /** * Tests what sort of wildcard expansion happens automatically. * It is very simple. Just look at the main method code to understand * what it does and what you could use it for. * * try with: * java WildcardExpansion *.* * java WildcardExpansion "*.*" * java WildcardExpansion s*.* * java WildcardExpansion . * java WildcardExpansion *.html * java WildcardExpansion afile.txt anotherfile.txt * java WildcardExpansion d?mmy.* (where you have dummy.* files and a dummy dir) * java WildcardExpansion t?mmy.* (where you don't have tummy.* files or a tummy dir) * * My discoveries: For Win2K: * Wildcards are automatically expanded before your program sees them. * Who does it? Presumably the command processor or a Sun class. * You get a list of matching files INCLUDING matching directory names, * but not the files in those subdirectories. Since directories normally * don't have extensions, you won't see the problem with *.html but you will * with s*.* or *.*. * If the wildcard does not match anything, you get the raw wildcard. * The wildcard in quotes gives you the raw wildcard. * Author Roedy Green * Version 1.0 */ public class WildcardExpansion { /** * Echo command line arguments, along with any automatic expansion * Can be used to test wildcard expansion, quoting, or any other basic features * features of command line parsing. * * @param args whatever you want to test. */ public static void main ( String[] args ) { System.out.println ( args.length + " arguments" ); for ( int i=0; i<args.length; i++ ) { // [ ] help prove no lead/trail blanks tabs etc. System.out.println( "[" + args[i] + "]" ); } } } SignatureBush crime family lost/embezzled $3 trillion from Pentagon. Complicit Bush-friendly media keeps mum. Rumsfeld confesses on video. http://www.infowars.com/articles/us/mckinney_grills_rumsfeld.htm Canadian Mind Products, Roedy Green. See http://mindprod.com/iraq.html photos of Bush's war crimes >>Portions of the essay are somewhat misleading. In Windows, it is not >>the command interpreter or BAT language that expands the wildcards. It [quoted text clipped - 68 lines] > } > } Yep, Win2000's cmd.exe seems to expand wildcard commandline arguments, not the JVM or the java.exe launcher. The expansion of 'd?mmy.*' to include a directory without a dot in its name seems to be consistent with the result of the command dir d?mmy.* The src.zip file in the JDK directory contains the C source of the Java launcher (java.exe / javaw.exe). As far as I could see, the launcher does not do any wildcard expansion. It does take care of handling the launcher specific argument (like -classpath, -Xmx128m, -showversion, etc.) and strips them from the arguments that eventually get passed to the Java main method. Looking at the C source also revealed that you can set the environment variable _JAVA_LAUNCHER_DEBUG to enable logging of the launcher. Here's an example of my trace: C:\temp>dir d?mmy.* Volume in drive C is NTFS Volume Serial Number is E8DA-EAA9 Directory of C:\temp 26-06-2005 10:01 49 dammy.txt 26-06-2005 11:59 <DIR> dummy 31-12-2004 14:49 957 Dummy.java 26-06-2005 10:00 52 dummy.txt 3 File(s) 1.058 bytes 1 Dir(s) 1.285.324.800 bytes free C:\temp>echo %CLASSPATH% .;.;.;c:\PROGRA~1\Java\JMF21~1.1\lib\sound.jar;c:\PROGRA~1\Java\JMF21~1.1\lib\jmf.jar;c:\PROGRA~1\Java\JMF21~1.1\lib;%systemroot%\java\classes;. C:\temp>set _JAVA_LAUNCHER_DEBUG=1 C:\temp>java -showversion -cp . WildcardExpansion d?mmy.* ----_JAVA_LAUNCHER_DEBUG---- Version major.minor.micro = 1.5.0 JRE path is C:\Program Files\Java\jre1.5.0 jvm.cfg[0] = ->-client<- jvm.cfg[1] = ->-server<- jvm.cfg[2] = ->-hotspot<- name: -hotspot vmType: VM_ALIASED_TO alias: -client jvm.cfg[3] = ->-classic<- jvm.cfg[4] = ->-native<- jvm.cfg[5] = ->-green<- 590 micro seconds to parse jvm.cfg Default VM: client JVM path is C:\Program Files\Java\jre1.5.0\bin\client\jvm.dll 4020 micro seconds to LoadJavaVM JavaVM args: version 0x00010002, ignoreUnrecognized is JNI_FALSE, nOptions is 3 option[ 0] = '-Djava.class.path=.;.;.;c:\PROGRA~1\Java\JMF21~1.1\lib\sound.jar;c:\PROGRA~1\Java\JMF21~1.1\lib\jmf.jar;c:\PROGRA~1\Java\JMF21~1.1\lib;%systemroot%\java\classes;.' option[ 1] = '-Djava.class.path=.' option[ 2] = '-Dsun.java.command=WildcardExpansion dammy.txt dummy dummy.java dummy.txt' java version "1.5.0_04" Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_04-b05) Java HotSpot(TM) Client VM (build 1.5.0_04-b05, mixed mode) 88566 micro seconds to InitializeJVM Main-Class is 'WildcardExpansion' Apps' argc is 4 argv[ 0] = 'dammy.txt' argv[ 1] = 'dummy' argv[ 2] = 'Dummy.java' argv[ 3] = 'dummy.txt' 34159 micro seconds to load main class ----_JAVA_LAUNCHER_DEBUG---- 4 arguments [dammy.txt] [dummy] [Dummy.java] [dummy.txt] C:\temp> SignatureRegards, Roland de Ruiter ` ___ ___ `/__/ w_/ /__/ / \ /_/ / \ >>> Portions of the essay are somewhat misleading. In Windows, it is not >>> the command interpreter or BAT language that expands the wildcards. [quoted text clipped - 147 lines] > > C:\temp> This analysis proves nothing. If you had bothered to look at the link for MSDN on command line expansion you would have learned that MS provides a library that does the command line wildcard expansion and that all you have to do is link to it for the wildcards to be expanded _before_ they are passed to your program. So, you cannot tell if wildcards are expanded just by looking at the source code and you cannot assume that the command processor is expanding wildcards by looking at what is passed to main(). Ray SignatureXML is the programmer's duct tape. >>Portions of the essay are somewhat misleading. In Windows, it is not >>the command interpreter or BAT language that expands the wildcards. It [quoted text clipped - 13 lines] > > try this out. I think you will be surprised. As I said before, if directories without '.' in the name are matched by *.*, that is a bug in the JVM. BTW, if you would like to prove to yourself that the expansion is done by the JVM and not the command processor, do not execute your programs from the command processor. Use Runtime.exec() to invoke the java.exe directly. Ray SignatureXML is the programmer's duct tape. >>> If you write *.* as a parameter, you don't see "*.*" appearing in >>> args[0]. Instead you see a list of all the filenames and directory [quoted text clipped - 27 lines] > I've checked the documentation for "java", and it does not describe this > behavior. This has to due with the way wildcard expansion is handled in Windows. Wildcard expansion is not handled by the command interpreter, as in Unix shells. Wildcard expansion is built into the console application (those of you familiar with Visual C++ will know t=what the settings are to do this). <http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vccelng/htm/bas ic_22.asp> HTH, Ray SignatureXML is the programmer's duct tape. ><http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vccelng/htm/bas ic_22.asp> So this implies the JRE is calling setargv or equivalent for you. In other words, the screw up is Sun's fault, not Microsofts that you can't tell a wildcard expansion asking for ONLY *.* files, from a list of directories and files to process keyed out longhand. SignatureBush crime family lost/embezzled $3 trillion from Pentagon. Complicit Bush-friendly media keeps mum. Rumsfeld confesses on video. http://www.infowars.com/articles/us/mckinney_grills_rumsfeld.htm Canadian Mind Products, Roedy Green. See http://mindprod.com/iraq.html photos of Bush's war crimes >><http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vccelng/htm/bas ic_22.asp> > > So this implies the JRE is calling setargv or equivalent for you. In > other words, the screw up is Sun's fault, not Microsofts that you > can't tell a wildcard expansion asking for ONLY *.* files, from a list > of directories and files to process keyed out longhand. Huh? I expected you to be saying the opposite. It is possible that to override setargv within your program by defining it yourself. However, from the source code that Sun provides, it appears they are not doing that. So the fault would lie in the default implementation of setargv and my claim that it is a JVM bug was premature. Ray SignatureXML is the programmer's duct tape. > I just discovered something odd. EVERY Java utility has wildcard > ability on the command line. [quoted text clipped - 18 lines] > Complicit Bush-friendly media keeps mum. Rumsfeld confesses on video. > http://www.infowars.com/articles/us/mckinney_grills_rumsfeld.htm > Canadian Mind Products, Roedy Green. > See http://mindprod.com/iraq.html photos of Bush's war crimes I'd think it is your command shell doing filename expansion, analogous to Bash's globbing: http://www.tldp.org/LDP/abs/html/globbingref.html > I just discovered something odd. EVERY Java utility has wildcard > ability on the command line. [quoted text clipped - 13 lines] > It is somewhat dangerous. *.* for a utility not prepared for it. *.* > does a directory 1-deep recursion. It is Windows that is doing it. I believe since 5.0 (Windows 2000) the command line will expand the wildcards * and ? before passing to a program. > -- > Bush crime family lost/embezzled $3 trillion from Pentagon. [quoted text clipped - 3 lines] > Canadian Mind Products, Roedy Green. > See http://mindprod.com/iraq.html photos of Bush's war crimes SignatureSend e-mail to: darrell dot grainger at utoronto dot ca . wrote: >>I just discovered something odd. EVERY Java utility has wildcard >>ability on the command line. [quoted text clipped - 17 lines] > command line will expand the wildcards * and ? before passing to a > program. I posted the following link as evidence that it is not the command interpreter but the application that expands wildcards: <http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vccelng/htm/bas ic_22.asp> If this did indeed change in Windows 2000, I would like to read some documentation on that. Can you provide a link? (While it is true that I do not think this is the case, my request is genuine.) Thanks, Ray SignatureXML is the programmer's duct tape. >I posted the following link as evidence that it is not the command >interpreter but the application that expands wildcards: > ><http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vccelng/htm/bas ic_22.asp> It depends how you define application. It is definitely no the java app you write that does it. The argument are expanded before they hit MAIN. It seems likely the JRE is doing it. SignatureBush crime family lost/embezzled $3 trillion from Pentagon. Complicit Bush-friendly media keeps mum. Rumsfeld confesses on video. http://www.infowars.com/articles/us/mckinney_grills_rumsfeld.htm Canadian Mind Products, Roedy Green. See http://mindprod.com/iraq.html photos of Bush's war crimes >>I posted the following link as evidence that it is not the command >>interpreter but the application that expands wildcards: [quoted text clipped - 4 lines] > app you write that does it. The argument are expanded before they hit > MAIN. It seems likely the JRE is doing it. Well, application here means from the perspective of the command line interpreter, which is the JRE. Yes, the arguments are expanded before they hit main(), either the main() in Java or the C main() function for the JRE. The wildcard expansion is done by setargv before the C main() function is invoked. You control whether you want this for your (C/C++) application by linking with a specific library that contains setargv. Ray SignatureXML is the programmer's duct tape. Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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