What is making “at” in AIX add a “cd /some/path/here” prior to my explicit commands?

Question

When I execute the following command:

cd /some/path/here
at -t 201409301100
ls -al
<CTRL-D>
at -lov

I get the following output:

========================
myusername.1411755840.a   Mon Sep 30 11:00:00 CDT 2014
========================
cd /some/path/here
ls -al

What is causing the cd /some/path/here command to appear? Other users on the same system are not seeing this behavior.

I'm using KornShell in AIX 6.1.

My .envfile contains:

if [ -t 0 ]; then
        case `who am i | awk '{print $1}'` in
                'myusername')
                        #set the prompt to include the date and time
                        #set -o allexport
                        unset _Y _M _D _h _m _s
                        eval $(date "+_Y=%Y;_M=%m;_D=%d;_h=%H;_m=%M;_s=%S")
                        ((SECONDS = 3600*${_h#0}+60*${_m#0}+${_s#0}))
                        typeset -Z2 _h _m _s
                        _tsub="(_m=(SECONDS/60%60)) == (_h=(SECONDS/3600%24)) + (_s=(SECONDS%60))"
                        #_timehm='${_x[_tsub]}$_h:${_m}'
                        #_timehms='${_x[_tsub]}$_h:$_m:${_s}'
                        _timedhms=$_Y'/'$_M'/'$_D" "'${_x[_tsub]}$_h:$_m:${_s}'
                        _hn=`hostname`
                        typeset -u _hn
                        _un=`whoami | awk '{print $1}'`
                        typeset -u _un
                        export PS1="$_timedhms
"'['$_un']'$_hn':${PWD#$HOME/} $ '
                        #set +o allexport
                ;;
                *)
                ;;
        esac
fi

Answer 1

An at job is executed in the directory where the at command was called.

Different implementations achieve that in different ways. It happens that yours does it by putting a cd command at the start of the job, before your code.

An at job is also executed in the same environment as when the at command was called, and with the same umask. AIX implements environment and umask preservation in some other way (I don't know how).