qsub passing an environment variable via cmd options -v

job.sh

#!/bin/bash --login
#PBS -N test
#PBS -A e283
#PBS -l select=1
#PBS -l walltime=0:20:00
##PBS -m abe
#PBS -M [email protected]

# Switch to current working directory
export PBS_O_WORKDIR=$(readlink -f $PBS_O_WORKDIR)
cd $PBS_O_WORKDIR

#### MODE is build or debug
if [ "x" == "x$MODE"  ] ; then
    echo "MODE is not set, I'll set it to build"
    MODE=build
else
    echo "MODE is: $MODE"
fi

export PATH=$PATH:/work/e283/e283/lhzhu/mpi_dvm3d/$MODE

date
aprun -n 4  -N 4  dvm3d.x > log 
date

### submit it using 
# qsub [-v MODE=debug] job.sh