How to remove the usage of temp file and read data from the command itself - bash

Question

I have a shell script and I need help to make it efficient. I am using temp files to store and read the data, but I need to read the data in memory.
It collects metrics from the Postgres database using a command and fetches the metrics. My current script fetches the metrics to a temp file, then reads from it.
I want to stop using temp files and use memory instead.
The script works, I just need help to automate more and get rid of reading data from temp files.
List item
INPUT=`mktemp`
#/usr/pgsql-9.5/bin/pgbench -c1 -j1 -t 1000 -S man > $INPUT
TESTTIME=15 #seconds
echo "Waiting $TESTTIME seconds..."
/usr/pgsql-9.5/bin/pgbench -c1 -j1 -T $TESTTIME -r man > $INPUT
OLDIFS=$IFS
IFS=" "
[ ! -f $INPUT ] && { echo "$INPUT file not found"; exit 99; }
tps=`cat $INPUT |awk '/^tps/ {print $3}' |awk -F'.' '{print $1}' |head -n1`
update_l=`cat $INPUT |awk '/UPDATE/ {print $1}' |tail -n1`
select_l=`cat $INPUT |awk '/SELECT/ {print $1}' |tail -n1`
insert_l=`cat $INPUT |awk '/INSERT/ {print $1}' |tail -n1`
echo ${PLOTTER_PREFIX}.tps $tps kv
echo ${PLOTTER_PREFIX}.update_latency $update_l kv
echo ${PLOTTER_PREFIX}.select_latency $select_l kv
echo ${PLOTTER_PREFIX}.insert_latency $insert_l kv
#{ while read line; do
# # statsite_buildData ${PLOTTER_PREFIX}.latency average ${latency average} kv
# echo ${PLOTTER_PREFIX}.${line} kv
# done } < $INPUT
statsite_sendData
#echo $Test
IFS=$OLDIFS
rm -f $INPUT

Answer 1

You can capture the output of the command to a variable, like so:
output=$(/usr/pgsql-9.5/bin/pgbench -c1 -j1 -T $TESTTIME -r man)
Then just use echo instead of cat and substitute $INPUT with the variable name.
tps=`echo "$output" | awk '/^tps/ {print $3}' | awk -F'.' '{print $1}' |head -n1`
update_l=`echo "$output" | awk '/UPDATE/ {print $1}' | tail -n1`
...
I would also suggest using $() instead of surrounding commands with backticks. So the above would become:
tps=$(echo "$output" | awk '/^tps/ {print $3}' | awk -F'.' '{print $1}' |head -n1)
update_l=$(echo "$output" | awk '/UPDATE/ {print $1}' | tail -n1)
...