To delete old files in unix, you can execute the following command from the shell:

find <path> -mtime +30 -exec rm -f {} \;

For example, to delete all file more than 30 days older:

find /tmp -mtime +30 -exec rm -f {} \;

# names store in "names" array.
names=( Dave Chris John Rob )

# here's how you iterate
for name in ${names[@]}
do
   echo $name
   # additional actions
done

# List of jobs
JOBS=( bp_daily1.sh cpn_daily1.sh )

# execute all jobs
for JOB in ${JOBS[@]}
do
   nohup $SRCDIR/${JOB} ${PROCESS_DATE} > $LOGDIR/${JOB}.out &
done

cat <all_files> > <big_file>

e.g.:

cat *.csv > master.csv

# get arguments
EXTRA=""
until [ $# -eq 0 ]
do
    EXTRA=$EXTRA" "$1
    shift;
done

# set 0 for false, 1 for true
VARTRIGGER=1
.
.
((VARTRIGGER)) && execute_anything;

head -10 orig.file > new.file

od -t x <file> 

set -o vi
<esc><>  for auto completion
<esc><=>  for list of possibilities