Executing who -m from ant - ant

Question

I am trying to execute the "who -m" command from Apache ant without success.
Here is my ant script:
<?xml version="1.0" encoding="UTF-8"?>
<project name="default" default="who.am.i">
<target name="who.am.i">
<exec executable="who" outputproperty="myOutput">
<arg value="-m"/>
</exec>
<echo message="I am = ${myOutput}"/>
</target>
</project>
The result is blank.
[echo] I am =
If I run exec without the argument, it displays the correct result:
<exec executable="who" outputproperty="myOutput">
</exec>
[echo] host.name = gary tty8 2014-02-03 12:04 (:0)
[echo] gary pts/0 2014-02-03 12:09 (:0)
[echo] gary pts/1 2014-02-03 12:23 (:0)
[echo] gary pts/2 2014-02-04 11:36 (:0)
[echo] gary pts/4 2014-02-05 13:27 (:0)
[echo] gary pts/7 2014-02-04 12:23 (:0)
[echo] gary pts/8 2014-02-06 12:44 (:0)
If I run the who -m command from a terminal it displays what I am looking for:
who -m
gary pts/8 2014-02-06 12:44 (:0)
Any ideas why ant is not accepting the -m argument?

Answer 1

Try executing as shell executable to see it that helps. It helps to invoke shell with exact unix command you want to run.
<exec executable="sh" outputproperty="myOutput">
<arg value="who -m"/>
</exec>

Answer 2

You don't mention which flavour of Unix you have, but on Solaris I get this error message when I try your task:
[echo] $ Must be attached to terminal for 'am I' option
In contrast, on OSX it appears to work, but says:
[echo] I am = mjc tty?? Feb 7 02:35
note the ?? - it's also not finding the terminal for the session.
I suspect that in your case it is silently failing for the same reason as the Solaris test - namely that the shell forked by Ant (i.e. by java) isn't associated with your terminal session.
(There may well be a workaround, but I'm not aware of it, and if there is one, it is unlikely to be portable.)

Answer 3

At the end of the day I decided to go another route.
In ~/.bashrc I added the following line:
who -m | awk '{print $5}' > ~/.whoami.out
And to make it global I just added it to /etc/bashrc
This will write to the ~/.whoami.out file every time I log into the remote system.
In my ant script I read the content of this file:
<?xml version="1.0" encoding="UTF-8"?>
<project name="default" default="default">
<target name="test.who.key">
<loadfile property="who.key" srcFile="${user.home}/.whoami.out" failonerror="false"/>
<condition property="who.cond">
<isset property="who.key"/>
</condition>
<condition property="who.cond2">
<not>
<isset property="who.key"/>
</not>
</condition>
</target>
<target name="init.who.key" depends="test.who.key" if="who.cond">
<echo message="WHO EXIST"/>
<property name="whoAmI" value="${who.key}"/>
</target>
<target name="init.not.who.key" depends="test.who.key" if="who.cond2">
<echo message="WHO DOES NOT EXIST"/>
<property name="whoAmI" value=""/>
</target>
<target name="default" depends="init.who.key, init.not.who.key">
<echo message="whoAmI = ${whoAmI}"/>
</target>
</project>