I have an Ant script that performs a copy operation using the copy task. It was written for Windows and has a hardcoded C:\ path as the todir argument. I see the exec task has an OS argument, is there a similar way to branch a copy based on OS?
You could use the condition task to branch to different copy tasks... from the ant manual:
<condition property="isMacOsButNotMacOsX">
<and>
<os family="mac"/>
<not>
<os family="unix"/>
</not>
</and>
Declare a variable that is the root folder of your operation. Prefix your folders with that variable, including in the copy task.
Set the variable based on the OS using a conditional, or pass it as an argument to the Ant script.
I would recommend putting the path in a property, then setting the property conditionally based on the current OS.
<condition property="foo.path" value="C:\Foo\Dir">
<os family="windows"/>
</condition>
<condition property="foo.path" value="/home/foo/dir">
<os family="unix"/>
</condition>
<fail unless="foo.path">No foo.path set for this OS!</fail>
As a side benefit, once it is in a property you can override it without editing the Ant script.
The previously posted suggestions of an OS specific variable will work, but many times you can simply omit the "C:" prefix and use forward slashes (Unix style) file paths and it will work on both Windows and Unix systems.
So, if you want to copy files to "C:/tmp" on Windows and "/tmp" on Unix, you could use something like:
<copy todir="/tmp" overwrite="true" >
<fileset dir="${lib.dir}">
<include name="*.jar" />
</fileset>
</copy>
If you do want/need to set a conditional path based on OS, it can be simplified as:
<condition property="root.drive" value="C:/" else="/">
<os family="windows" />
</condition>
<copy todir="${root.drive}tmp" overwrite="true" >
<fileset dir="${lib.dir}">
<include name="*.jar" />
</fileset>
</copy>
Ant-contrib has the <osfamily /> task. This will expose the family of the os to a property (that you specify the name of). This could be of some benefit.