author | erikj |
Mon, 19 Mar 2018 10:11:07 -0700 | |
changeset 49263 | 78af880eec61 |
parent 47216 | 71c04702a3d5 |
child 49424 | 4269e701448e |
permissions | -rw-r--r-- |
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'\" t |
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.\" Copyright (c) 1995, 2013, Oracle and/or its affiliates. All rights reserved. |
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.\" DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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.\" |
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.\" This code is free software; you can redistribute it and/or modify it |
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.\" under the terms of the GNU General Public License version 2 only, as |
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.\" published by the Free Software Foundation. |
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.\" |
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.\" This code is distributed in the hope that it will be useful, but WITHOUT |
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.\" ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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.\" FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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.\" version 2 for more details (a copy is included in the LICENSE file that |
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.\" accompanied this code). |
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.\" |
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.\" You should have received a copy of the GNU General Public License version |
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.\" 2 along with this work; if not, write to the Free Software Foundation, |
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.\" Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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.\" |
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.\" Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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.\" or visit www.oracle.com if you need additional information or have any |
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.\" questions. |
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.\" |
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.\" Arch: generic |
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.\" Software: JDK 8 |
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.\" Date: 21 November 2013 |
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.\" SectDesc: Basic Tools |
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.\" Title: jdb.1 |
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.\" |
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.if n .pl 99999 |
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.TH jdb 1 "21 November 2013" "JDK 8" "Basic Tools" |
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.\" ----------------------------------------------------------------- |
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.\" * Define some portability stuff |
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.\" ----------------------------------------------------------------- |
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
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.\" http://bugs.debian.org/507673 |
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.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html |
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
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.ie \n(.g .ds Aq \(aq |
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.el .ds Aq ' |
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.\" ----------------------------------------------------------------- |
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.\" * set default formatting |
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.\" ----------------------------------------------------------------- |
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.\" disable hyphenation |
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.nh |
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.\" disable justification (adjust text to left margin only) |
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.ad l |
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.\" ----------------------------------------------------------------- |
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.\" * MAIN CONTENT STARTS HERE * |
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.\" ----------------------------------------------------------------- |
2 | 50 |
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.SH NAME |
52 |
jdb \- Finds and fixes bugs in Java platform programs\&. |
|
53 |
.SH SYNOPSIS |
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.sp |
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.nf |
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\fBjdb\fR [\fIoptions\fR] [\fIclassname\fR] [\fIarguments\fR] |
58 |
.fi |
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.sp |
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60 |
.TP |
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\fIoptions\fR |
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Command-line options\&. See Options\&. |
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.TP |
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\fIclass\fRname |
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Name of the main class to debug\&. |
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.TP |
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\fIarguments\fR |
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Arguments passed to the \f3main()\fR method of the class\&. |
|
69 |
.SH DESCRIPTION |
|
70 |
The Java Debugger (JDB) is a simple command-line debugger for Java classes\&. The \f3jdb\fR command and its options call the JDB\&. The \f3jdb\fR command demonstrates the Java Platform Debugger Architecture (JDBA) and provides inspection and debugging of a local or remote Java Virtual Machine (JVM)\&. See Java Platform Debugger Architecture (JDBA) at http://docs\&.oracle\&.com/javase/8/docs/technotes/guides/jpda/index\&.html |
|
71 |
.SS START\ A\ JDB\ SESSION |
|
72 |
There are many ways to start a JDB session\&. The most frequently used way is to have JDB launch a new JVM with the main class of the application to be debugged\&. Do this by substituting the \f3jdb\fR command for the \f3java\fR command in the command line\&. For example, if your application\&'s main class is \f3MyClass\fR, then use the following command to debug it under JDB: |
|
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.sp |
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.nf |
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\f3jdb MyClass\fP |
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.fi |
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.nf |
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\f3\fP |
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.fi |
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.sp |
|
81 |
When started this way, the \f3jdb\fR command calls a second JVM with the specified parameters, loads the specified class, and stops the JVM before executing that class\&'s first instruction\&. |
|
82 |
.PP |
|
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Another way to use the \f3jdb\fR command is by attaching it to a JVM that is already running\&. Syntax for starting a JVM to which the \f3jdb\fR command attaches when the JVM is running is as follows\&. This loads in-process debugging libraries and specifies the kind of connection to be made\&. |
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.sp |
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.nf |
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\f3java \-agentlib:jdwp=transport=dt_socket,server=y,suspend=n MyClass\fP |
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.fi |
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.nf |
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\f3\fP |
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.fi |
|
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.sp |
|
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You can then attach the \f3jdb\fR command to the JVM with the following command: |
|
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.sp |
|
94 |
.nf |
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\f3jdb \-attach 8000\fP |
|
96 |
.fi |
|
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.nf |
|
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\f3\fP |
|
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.fi |
|
100 |
.sp |
|
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The \f3MyClass\fR argument is not specified in the \f3jdb\fR command line in this case because the \f3jdb\fR command is connecting to an existing JVM instead of launching a new JVM\&. |
|
102 |
.PP |
|
103 |
There are many other ways to connect the debugger to a JVM, and all of them are supported by the \f3jdb\fR command\&. The Java Platform Debugger Architecture has additional documentation on these connection options\&. |
|
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.SS BASIC\ JDB\ COMMANDS |
|
105 |
The following is a list of the basic \f3jdb\fR commands\&. The JDB supports other commands that you can list with the \f3-help\fR option\&. |
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.TP |
|
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help or ? |
|
108 |
The \f3help\fR or \f3?\fR commands display the list of recognized commands with a brief description\&. |
|
109 |
.TP |
|
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run |
|
111 |
After you start JDB and set breakpoints, you can use the \f3run\fR command to execute the debugged application\&. The \f3run\fR command is available only when the \f3jdb\fR command starts the debugged application as opposed to attaching to an existing JVM\&. |
|
112 |
.TP |
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113 |
cont |
|
114 |
Continues execution of the debugged application after a breakpoint, exception, or step\&. |
|
115 |
.TP |
|
116 |
||
117 |
Displays Java objects and primitive values\&. For variables or fields of primitive types, the actual value is printed\&. For objects, a short description is printed\&. See the dump command to find out how to get more information about an object\&. |
|
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\fINote:\fR To display local variables, the containing class must have been compiled with the \f3javac -g\fR option\&. |
2 | 120 |
|
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The \f3print\fR command supports many simple Java expressions including those with method invocations, for example: |
122 |
.sp |
|
123 |
.nf |
|
124 |
\f3print MyClass\&.myStaticField\fP |
|
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.fi |
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126 |
.nf |
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127 |
\f3print myObj\&.myInstanceField\fP |
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.fi |
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.nf |
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\f3print i + j + k (i, j, k are primities and either fields or local variables)\fP |
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.fi |
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.nf |
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\f3print myObj\&.myMethod() (if myMethod returns a non\-null)\fP |
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.fi |
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135 |
.nf |
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\f3print new java\&.lang\&.String("Hello")\&.length()\fP |
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.fi |
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.nf |
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\f3\fP |
|
140 |
.fi |
|
141 |
.sp |
|
142 |
||
143 |
.TP |
|
144 |
dump |
|
145 |
For primitive values, the \f3dump\fR command is identical to the \f3print\fR command\&. For objects, the \f3dump\fR command prints the current value of each field defined in the object\&. Static and instance fields are included\&. The \f3dump\fR command supports the same set of expressions as the \f3print\fR command\&. |
|
146 |
.TP |
|
147 |
threads |
|
148 |
List the threads that are currently running\&. For each thread, its name and current status are printed and an index that can be used in other commands\&. In this example, the thread index is 4, the thread is an instance of \f3java\&.lang\&.Thread\fR, the thread name is \f3main\fR, and it is currently running\&. |
|
149 |
.sp |
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150 |
.nf |
|
151 |
\f34\&. (java\&.lang\&.Thread)0x1 main running\fP |
|
152 |
.fi |
|
153 |
.nf |
|
154 |
\f3\fP |
|
155 |
.fi |
|
156 |
.sp |
|
157 |
||
158 |
.TP |
|
159 |
thread |
|
160 |
Select a thread to be the current thread\&. Many \f3jdb\fR commands are based on the setting of the current thread\&. The thread is specified with the thread index described in the threads command\&. |
|
161 |
.TP |
|
162 |
where |
|
163 |
The \f3where\fR command with no arguments dumps the stack of the current thread\&. The \f3where\fR\f3all\fR command dumps the stack of all threads in the current thread group\&. The \f3where\fR\f3threadindex\fR command dumps the stack of the specified thread\&. |
|
164 |
||
165 |
If the current thread is suspended either through an event such as a breakpoint or through the \f3suspend\fR command, then local variables and fields can be displayed with the \f3print\fR and \f3dump\fR commands\&. The \f3up\fR and \f3down\fR commands select which stack frame is the current stack frame\&. |
|
166 |
.SS BREAKPOINTS |
|
167 |
Breakpoints can be set in JDB at line numbers or at the first instruction of a method, for example: |
|
168 |
.TP 0.2i |
|
169 |
\(bu |
|
170 |
The command \f3stop at MyClass:22\fR sets a breakpoint at the first instruction for line 22 of the source file containing \f3MyClass\fR\&. |
|
171 |
.TP 0.2i |
|
172 |
\(bu |
|
173 |
The command \f3stop in java\&.lang\&.String\&.length\fR sets a breakpoint at the beginning of the method \f3java\&.lang\&.String\&.length\fR\&. |
|
174 |
.TP 0.2i |
|
175 |
\(bu |
|
176 |
The command \f3stop in MyClass\&.<clinit>\fR uses \f3<clinit>\fR to identify the static initialization code for \f3MyClass\fR\&. |
|
177 |
.PP |
|
178 |
When a method is overloaded, you must also specify its argument types so that the proper method can be selected for a breakpoint\&. For example, \f3MyClass\&.myMethod(int,java\&.lang\&.String)\fR or \f3MyClass\&.myMethod()\fR\&. |
|
179 |
.PP |
|
180 |
The \f3clear\fR command removes breakpoints using the following syntax: \f3clear MyClass:45\fR\&. Using the \f3clear\fR or \f3stop\fR command with no argument displays a list of all breakpoints currently set\&. The \f3cont\fR command continues execution\&. |
|
181 |
.SS STEPPING |
|
182 |
The \f3step\fR command advances execution to the next line whether it is in the current stack frame or a called method\&. The \f3next\fR command advances execution to the next line in the current stack frame\&. |
|
183 |
.SS EXCEPTIONS |
|
184 |
When an exception occurs for which there is not a \f3catch\fR statement anywhere in the throwing thread\&'s call stack, the JVM typically prints an exception trace and exits\&. When running under JDB, however, control returns to JDB at the offending throw\&. You can then use the \f3jdb\fR command to diagnose the cause of the exception\&. |
|
185 |
.PP |
|
186 |
Use the \f3catch\fR command to cause the debugged application to stop at other thrown exceptions, for example: \f3catch java\&.io\&.FileNotFoundException\fR or \f3catch\fR\f3mypackage\&.BigTroubleException\fR\&. Any exception that is an instance of the specified class or subclass stops the application at the point where it is thrown\&. |
|
187 |
.PP |
|
188 |
The \f3ignore\fR command negates the effect of an earlier \f3catch\fR command\&. The \f3ignore\fR command does not cause the debugged JVM to ignore specific exceptions, but only to ignore the debugger\&. |
|
189 |
.SH OPTIONS |
|
190 |
When you use the \f3jdb\fR command instead of the \f3java\fR command on the command line, the \f3jdb\fR command accepts many of the same options as the \f3java\fR command, including \f3-D\fR, \f3-classpath\fR, and \f3-X\fR options\&. The following list contains additional options that are accepted by the \f3jdb\fR command\&. |
|
191 |
.PP |
|
192 |
Other options are supported to provide alternate mechanisms for connecting the debugger to the JVM it is to debug\&. For additional documentation about these connection alternatives, see Java Platform Debugger Architecture (JPDA) at http://docs\&.oracle\&.com/javase/8/docs/technotes/guides/jpda/index\&.html |
|
193 |
.TP |
|
194 |
-help |
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.br |
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Displays a help message\&. |
197 |
.TP |
|
198 |
-sourcepath \fIdir1:dir2: \&. \&. \&.\fR |
|
199 |
.br |
|
200 |
Uses the specified path to search for source files in the specified path\&. If this option is not specified, then use the default path of dot (\&.)\&. |
|
201 |
.TP |
|
202 |
-attach \fIaddress\fR |
|
203 |
.br |
|
204 |
Attaches the debugger to a running JVM with the default connection mechanism\&. |
|
205 |
.TP |
|
206 |
-listen \fIaddress\fR |
|
207 |
.br |
|
208 |
Waits for a running JVM to connect to the specified address with a standard connector\&. |
|
209 |
.TP |
|
210 |
-launch |
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.br |
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Starts the debugged application immediately upon startup of JDB\&. The \f3-launch\fR option removes the need for the \f3run\fR command\&. The debugged application is launched and then stopped just before the initial application class is loaded\&. At that point, you can set any necessary breakpoints and use the \f3cont\fR command to continue execution\&. |
213 |
.TP |
|
214 |
-listconnectors |
|
9573 | 215 |
.br |
21743 | 216 |
List the connectors available in this JVM\&. |
217 |
.TP |
|
218 |
-connect connector-name:\fIname1=value1\fR |
|
219 |
.br |
|
220 |
Connects to the target JVM with the named connector and listed argument values\&. |
|
221 |
.TP |
|
222 |
-dbgtrace [\fIflags\fR] |
|
9573 | 223 |
.br |
21743 | 224 |
Prints information for debugging the \f3jdb\fR command\&. |
225 |
.TP |
|
226 |
-tclient |
|
227 |
.br |
|
228 |
Runs the application in the Java HotSpot VM client\&. |
|
229 |
.TP |
|
230 |
-tserver |
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.br |
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Runs the application in the Java HotSpot VM server\&. |
233 |
.TP |
|
234 |
-J\fIoption\fR |
|
235 |
.br |
|
236 |
Passes \f3option\fR to the JVM, where option is one of the options described on the reference page for the Java application launcher\&. For example, \f3-J-Xms48m\fR sets the startup memory to 48 MB\&. See java(1)\&. |
|
237 |
.SH OPTIONS\ FORWARDED\ TO\ THE\ DEBUGGER\ PROCESS |
|
238 |
.TP |
|
239 |
-v -verbose[:\fIclass\fR|gc|jni] |
|
240 |
.br |
|
241 |
Turns on verbose mode\&. |
|
242 |
.TP |
|
243 |
-D\fIname\fR=\fIvalue\fR |
|
244 |
.br |
|
245 |
Sets a system property\&. |
|
246 |
.TP |
|
247 |
-classpath \fIdir\fR |
|
248 |
.br |
|
249 |
Lists directories separated by colons in which to look for classes\&. |
|
250 |
.TP |
|
251 |
-X\fIoption\fR |
|
252 |
.br |
|
253 |
Nonstandard target JVM option\&. |
|
254 |
.SH SEE\ ALSO |
|
255 |
.TP 0.2i |
|
256 |
\(bu |
|
257 |
javac(1) |
|
258 |
.TP 0.2i |
|
259 |
\(bu |
|
260 |
java(1) |
|
261 |
.TP 0.2i |
|
262 |
\(bu |
|
263 |
javah(1) |
|
264 |
.TP 0.2i |
|
265 |
\(bu |
|
266 |
javap(1) |
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.RE |
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.br |
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parents:
21743
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269 |
'pl 8.5i |
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8131105: Header Template for nroff man pages *.1 files contains errors
mfang
parents:
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270 |
'bp |