Ant How to execute a command for each file in directory

Question

I want to execute a command from an Ant buildfile  for each file in a directory  I am looking for a platform-independent solution   How do I do this   Sure  I could write a script in some scripting language  but this would add further dependencies to the project

User · Answer

I know this post is realy old but now that some time and ant versions passed there is a way to do this with basic ant features and i thought i should share it.

It's done via a recursive macrodef that calls nested tasks (even other macros may be called). The only convention is to use a fixed variable name (element here).

<project name="iteration-test" default="execute" xmlns="antlib:org.apache.tools.ant" xmlns:if="ant:if" xmlns:unless="ant:unless">

    <macrodef name="iterate">
        <attribute name="list" />
        <element name="call" implicit="yes" />
        <sequential>
            <local name="element" />
            <local name="tail" />
            <local name="hasMoreElements" />
            <!-- unless to not get a error on empty lists -->
            <loadresource property="element" unless:blank="@{list}" >
                <concat>@{list}</concat>
                <filterchain>
                    <replaceregex pattern="([^;]*).*" replace="\1" />
                </filterchain>
            </loadresource>
            <!-- call the tasks that handle the element -->
            <call />

            <!-- recursion -->
            <condition property="hasMoreElements">
                <contains string="@{list}" substring=";" />
            </condition>

            <loadresource property="tail" if:true="${hasMoreElements}">
                <concat>@{list}</concat>
                <filterchain>
                    <replaceregex pattern="[^;]*;(.*)" replace="\1" />
                </filterchain>
            </loadresource>

            <iterate list="${tail}" if:true="${hasMoreElements}">
                <call />
            </iterate>
        </sequential>
    </macrodef>

    <target name="execute">
        <fileset id="artifacts.fs" dir="build/lib">
            <include name="*.jar" />
            <include name="*.war" />
        </fileset>

        <pathconvert refid="artifacts.fs" property="artifacts.str" />

        <echo message="$${artifacts.str}: ${artifacts.str}" />
        <!-- unless is required for empty lists to not call the enclosed tasks -->
        <iterate list="${artifacts.str}" unless:blank="${artifacts.str}">
            <echo message="I see:" />
            <echo message="${element}" />
        </iterate>
        <!-- local variable is now empty -->
        <echo message="${element}" />
    </target>
</project>

The key features needed where:

http://ant.apache.org/manual/ifunless.html introduced in ant 1.9.1 (credits to ant conditional if within a macrodef)
substrings, many thanks to How to pull out a substring in Ant
the inline macrodef element.

I didnt manage to make the delimiter variabel, but this may not be a major downside.

User · Answer

Here is way to do this using javascript and the ant scriptdef task  you don t need ant-contrib for this code to work since scriptdef is a core ant task    lt scriptdef name  bzip2-files  language  javascript  gt   lt element name  fileset  type  fileset   gt   lt   CDATA    importClass java io File     filesets   elements get  fileset       for  i   0  i  lt  filesets size      i        fileset   filesets get i       scanner   fileset getDirectoryScanner project       scanner scan        files   scanner getIncludedFiles        for  j 0  j  lt  files length  j               var basedir    fileset getDir project           var filename   files j           var src   new File basedir  filename           var dest  new File basedir  filename     bz2             bzip2   self project createTask  bzip2                    bzip2 setSrc  src           bzip2 setDestfile dest             bzip2 execute                 gt   lt  scriptdef gt    lt bzip2-files gt       lt fileset id  test  dir  upstream classpath jars development  gt               lt include name       jar    gt       lt  fileset gt   lt  bzip2-files gt

User · Answer

An approach without ant-contrib is suggested by Tassilo Horn  the original target is here   Basicly  as there is no extension of  lt java gt   yet   in the same way  that  lt apply gt  extends  lt exec gt   he suggests to use  lt apply gt   which can of course also run a java programm in a command line   Here some examples      lt apply executable  java  gt        lt arg value  -cp   gt        lt arg pathref  classpath   gt        lt arg value  -f   gt        lt srcfile  gt        lt arg line  -o   output dir    gt         lt fileset dir    input dir   includes    txt   gt      lt  apply gt

User · Answer

Use the  lt apply gt  task   It executes a command once for each file  Specify the files by means of filesets or any other resource   lt apply gt  is built-in  no additional dependency needed  no custom task implementation needed   It s also possible to run the command only once  appending all files as arguments in one go  Use the parallel attribute to switch the behaviour   Sorry for being late a year

User · Answer

ant-contrib is evil  write a custom ant task   ant-contrib is evil because it tries to convert ant from a declarative style to an imperative style  But xml makes a crap programming language   By contrast a custom ant task allows you to write in a real language  Java   with a real IDE  where you can write unit tests to make sure you have the behavior you want  and then make a clean declaration in your build script about the behavior you want   This rant only matters if you care about writing maintainable ant scripts  If you don t care about maintainability by all means do whatever works      Jtf

User · Answer

Do what blak3r suggested and define your targets classpath like so    lt taskdef resource  net sf antcontrib antlib xml  gt       lt classpath gt           lt fileset dir  lib  gt             lt include name       jar   gt           lt  fileset gt       lt  classpath gt           lt  taskdef gt    where lib is where you store your jar s

User · Answer

You can use the ant-contrib task  for  to iterate on the list of files separate by any delimeter  default delimeter is       Following is the sample file which shows this    lt project name  modify-files  default  main  basedir     gt       lt taskdef resource  net sf antcontrib antlib xml   gt       lt target name  main  gt           lt for list  FileA FileB FileC FileD FileE  param  file  gt             lt sequential gt               lt echo gt Updating file    file  lt  echo gt               lt  -- Do something with file here -- gt             lt  sequential gt           lt  for gt                                lt  target gt   lt  project gt

User · Answer

Short Answer  Use  lt foreach gt  with a nested  lt FileSet gt   Foreach requires ant-contrib   Updated Example for recent ant-contrib    lt target name  foo  gt     lt foreach target  bar  param  theFile  gt       lt fileset dir    server src   casesensitive  yes  gt         lt include name       java   gt         lt exclude name      Test    gt       lt  fileset gt     lt  foreach gt   lt  target gt    lt target name  bar  gt     lt echo message    theFile    gt   lt  target gt    This will antcall the target  bar  with the   theFile  resulting in the current file

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