[OS] Time spent on the OS Server

#!/bin/bash
#if the number of arguments is not 1, as it should be, show USAGE message and exit.
if [ $# -ne 1 ]
then
    echo "USAGE: `basename $0` br_indeks"
    exit 1
fi
#Create a file with the given name, but delete it first if a file with that name already exists.
if [ -f out.txt ]
then
    rm out.txt
fi
touch out.txt
#select all the rows that start with the first argument
#leave out their 10th column only
#substitute the each brace type with empty space as we don't need them
#make two dots as our new internal field separator and initialize the total variable to calculate total time spent on the OS server
#send the calculation to our newly promoted script varible user_time
user_time=`last | grep ^$1 | awk 'print $10;' | sed -e 's/(//' -e 's/)//' | awk -F: 'BEGIN {total=0;} {total+=$1*60+$2;} END {print total;}'`
#send user_time'z value as a text for out.txt
echo "$user_time" >> out.txt
#list the text in out.txt on the console
cat out.txt