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| <title>Exec Task</title> |
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| <h2><a name="exec">Exec</a></h2> |
| <h3>Description</h3> |
| <p>Executes a system command. When the <i>os</i> attribute is specified, then |
| the command is only executed when Ant is run on one of the specified operating |
| systems.</p> |
| <h3>Parameters</h3> |
| <table border="1" cellpadding="2" cellspacing="0"> |
| <tr> |
| <td valign="top"><b>Attribute</b></td> |
| <td valign="top"><b>Description</b></td> |
| <td align="center" valign="top"><b>Required</b></td> |
| </tr> |
| <tr> |
| <td valign="top">command</td> |
| <td valign="top">the command to execute with all command line |
| arguments. <b>deprecated, use executable and nested |
| <code><arg></code> elements instead</b>.</td> |
| <td align="center" rowspan="2">Exactly one of the two.</td> |
| </tr> |
| <tr> |
| <td valign="top">executable</td> |
| <td valign="top">the command to execute without any command line |
| arguments.</td> |
| </tr> |
| <tr> |
| <td valign="top">dir</td> |
| <td valign="top">the directory in which the command should be executed.</td> |
| <td align="center" valign="top">No</td> |
| </tr> |
| <tr> |
| <td valign="top">os</td> |
| <td valign="top">list of Operating Systems on which the command may be |
| executed. If the current OS's name is contained in this list, the command will |
| be executed. The OS's name is determined by the Java Virtual machine and is set |
| in the "os.name" system property.</td> |
| <td align="center" valign="top">No</td> |
| </tr> |
| <tr> |
| <td valign="top">output</td> |
| <td valign="top">the file to which the output of the command should be |
| redirected.</td> |
| <td align="center" valign="top">No</td> |
| </tr> |
| <tr> |
| <td valign="top">append</td> |
| <td valign="top">whether output should be appended to or overwrite |
| an existing file. Defaults to false.</td> |
| <td align="center" valign="top">No</td> |
| </tr> |
| <tr> |
| <td valign="top">outputproperty</td> |
| <td valign="top">the name of a property in which the output of the |
| command should be stored.</td> |
| <td align="center" valign="top">No</td> |
| </tr> |
| <tr> |
| <td valign="top">resultproperty</td> |
| <td valign="top">the name of a property in which the return code of the |
| command should be stored. Only of interest if failonerror=false</td> |
| <td align="center" valign="top">No</td> |
| </tr> |
| <tr> |
| <td valign="top">timeout</td> |
| <td valign="top">Stop the command if it doesn't finish within the |
| specified time (given in milliseconds).</td> |
| <td align="center" valign="top">No</td> |
| </tr> |
| <tr> |
| <td valign="top">failonerror</td> |
| <td valign="top">Stop the buildprocess if the command exits with a |
| returncode other than 0. Defaults to false</td> |
| <td align="center" valign="top">No</td> |
| </tr> |
| <tr> |
| <td valign="top">failifexecutionfails</td> |
| <td valign="top">Stop the build if we can't start the program. |
| Defaults to true. </td> |
| <td align="center" valign="top">No</td> |
| </tr> <tr> |
| <td valign="top">newenvironment</td> |
| <td valign="top">Do not propagate old environment when new environment |
| variables are specified.</td> |
| <td align="center" valign="top">No, default is <i>false</i></td> |
| </tr> |
| <tr> |
| <td valign="top">vmlauncher</td> |
| <td valign="top">Run command using the Java VM's execution facilities |
| where available. If set to false the underlying OS's shell, |
| either directly or through the antRun scripts, will be used. |
| Under some operating systems, this gives access to facilities |
| not normally available through the VM including, under Windows, |
| being able to execute scripts, rather than their associated |
| interpreter. If you want to specify the name of the |
| executable as a relative path to the directory given by the |
| dir attribute, it may become necessary to set vmlauncher to |
| false as well.</td> |
| <td align="center" valign="top">No, default is <i>true</i></td> |
| </tr> |
| </table> |
| <h3>Examples</h3> |
| <blockquote> |
| <pre> |
| <exec dir="${src}" executable="cmd.exe" os="Windows 2000" output="dir.txt"> |
| <arg line="/c dir"/> |
| </exec></pre> |
| </blockquote> |
| <h3>Parameters specified as nested elements</h3> |
| <h4>arg</h4> |
| <p>Command line arguments should be specified as nested |
| <code><arg></code> elements. See <a |
| href="../using.html#arg">Command line arguments</a>.</p> |
| <h4><a name="env">env</a></h4> |
| <p>It is possible to specify environment variables to pass to the |
| system command via nested <code><env></code> elements.</p> |
| <table border="1" cellpadding="2" cellspacing="0"> |
| <tr> |
| <td valign="top"><b>Attribute</b></td> |
| <td valign="top"><b>Description</b></td> |
| <td align="center" valign="top"><b>Required</b></td> |
| </tr> |
| <tr> |
| <td valign="top">key</td> |
| <td valign="top">The name of the environment variable.</td> |
| <td align="center" valign="top">Yes</td> |
| </tr> |
| <tr> |
| <td valign="top">value</td> |
| <td valign="top">The literal value for the environment variable.</td> |
| <td align="center" rowspan="3">Exactly one of these.</td> |
| </tr> |
| <tr> |
| <td valign="top">path</td> |
| <td valign="top">The value for a PATH like environment |
| variable. You can use ; or : as path separators and Ant will |
| convert it to the platform's local conventions.</td> |
| </tr> |
| <tr> |
| <td valign="top">file</td> |
| <td valign="top">The value for the environment variable. Will be |
| replaced by the absolute filename of the file by Ant.</td> |
| </tr> |
| </table> |
| |
| <h3>Errors and return codes</h3> |
| By default the return code of a <exec> is ignored; when you set |
| <code>failonerror="true"</code> then any non zero response is treated as an |
| error. Alternatively, you can set <code>resultproperty</code> to the name |
| of a property and have it assigned to the result code (barring immutability, |
| of course). |
| <p> |
| If the attempt to start the program fails with an OS dependent error code, |
| then <exec> halts the build unless <code>failifexecutionfails</code> |
| is set. You can use that to run a program if it exists, but otherwise |
| do nothing. |
| <p> |
| What do those error codes mean? Well, they are OS dependent. On Windows |
| boxes you have to look in include\error.h in your windows compiler or wine files; |
| error code 2 means 'no such program', which usually means it is not on the path. |
| Any time you see such an error from any ant task, it is usually not an ant bug, |
| but some configuration problem on your machine. |
| |
| <h3>Examples</h3> |
| <blockquote><pre> |
| <exec executable="emacs" > |
| <env key="DISPLAY" value=":1.0"/> |
| </exec> |
| </pre></blockquote> |
| <p>starts <code>emacs</code> on display 1 of the X Window System.</p> |
| <blockquote><pre> |
| <exec ... > |
| <env key="PATH" path="${java.library.path}:${basedir}/bin"/> |
| </exec> |
| </pre></blockquote> |
| <p>adds <code>${basedir}/bin</code> to the <code>PATH</code> of the |
| system command.</p> |
| <p><b>Note:</b> Although it may work for you to specify arguments using |
| a simple arg-element and separate them by spaces it may fail if you switch to |
| a newer version of the JDK. JDK < 1.2 will pass these as separate arguments |
| to the program you are calling, JDK >= 1.2 will pass them as a single |
| argument and cause most calls to fail.</p> |
| <p><b>Note2:</b> If you are using Ant on Windows and a new DOS-Window pops up |
| for every command which is executed this may be a problem of the JDK you are using. |
| This problem may occur with all JDK's < 1.2.</p> |
| <p> |
| <b>Timeouts: </b> If a timeout is specified, when it is reached the |
| sub process is killed and a message printed to the log. The return |
| value of the execution will be "-1", which will halt the build if |
| <tt>failonerror=true</tt>, but be ignored otherwise. |
| <hr> |
| <p align="center">Copyright © 2000-2002 Apache Software Foundation. All rights |
| Reserved.</p> |
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