Touch Task

## Touch

### Description

Changes the modification time of a resource and possibly creates it at the same time. In addition to working with a single file, this Task can also work on resources and resource collections (which also includes directories). Prior to Apache Ant 1.7 only FileSet or Filelist (since Ant 1.6) have been supported.

Ant uses the API of `java.io.File` to set the last modification time which has some limitations. For example the timestamp granularity depends on the operating system and sometimes the operating system may allow a granularity smaller than milliseconds. If you need more control you have to fall back to the `<exec>` task and native commands.

Starting with Ant 1.8.2 Ant will log a warning message if it fails to change the file modification time. This will happen if you try to change the modification time of a file you do not own on many Unix systems, for example.

### Parameters

Attribute | Description | Required
file | The name of the file. | Unless a nested resource collection element has been specified.
millis | Specifies the new modification time of the file in milliseconds since midnight Jan 1 1970. | No--datetime takes precedence, however if both are omitted the current time is assumed.
datetime | Specifies the new modification time of the file. The special value "now" indicates the current time (now supported since Ant 1.8).
pattern | SimpleDateFormat-compatible pattern string using the current locale. Defaults to "MM/dd/YYYY hh:mm a" or "MM/dd/yyyy hh:mm:ss a" using the US locale. Since Ant 1.6.3 | No
mkdirs | Whether to create nonexistent parent directories when touching new files. Since Ant 1.6.3 | No, default false.
verbose | Whether to log the creation of new files. Since Ant 1.6.3 | No, default true.

### Parameters specified as nested elements

#### any resource collection

You can use any number of nested resource collection elements to define the resources for this task and refer to resources defined elsewhere. Note: resources passed to this task must implement the `org.apache.tools.ant.types.resources.Touchable` interface, this is true for all filesystem-based resources like those returned by path, fileset ot filelist.

For backwards compatibility directories matched by nested filesets will be "touched" as well, use a <type> selector to suppress this. This only applies to filesets nested into the task directly, not to filesets nested into a path or any other resource collection.

#### mapper

Since Ant 1.6.3, a nested mapper can be specified. Files specified via nested `fileset`s, `filelist`s, or the `file` attribute are mapped using the specified mapper. For each file mapped, the resulting files are touched. If no time has been specified and the original file exists its timestamp will be used. If no time has been specified and the original file does not exist the current time is used. Since Ant 1.8 the task settings (`millis`, and `datetime`) have priority over the timestamp of the original file.

### Examples

      <touch file="myfile"/>

creates `myfile` if it doesn't exist and changes the modification time to the current time.

      <touch file="myfile" datetime="06/28/2000 2:02 pm"/>

creates `myfile` if it doesn't exist and changes the modification time to Jun, 28 2000 2:02 pm (14:02 for those used to 24 hour times).

      <touch datetime="09/10/1974 4:30 pm">
        <fileset dir="src_dir"/>
      </touch>

changes the modification time to Oct, 09 1974 4:30 pm of all files and directories found in `src_dir`.

      <touch file="myfile" datetime="06/28/2000 2:02:17 pm"/>

creates `myfile` if it doesn't exist and changes the modification time to Jun, 28 2000 2:02:17 pm (14:02:17 for those used to 24 hour times), if the filesystem allows a precision of one second - a time close to it otherwise.

      <touch file="foo">
        <mapper type="glob" from="foo" to="bar" />
      </touch>

creates `bar` if it doesn't exist and changes the modification time to that of `foo`.

      <touch file="foo" datetime="now">
        <mapper type="regexp" from="^src(.*)\.java" to="shadow\1.empty" />
      </touch>

creates files in the `shadow` directory for every java file in the `src` directory if it doesn't exist and changes the modification time of those files to the current time.