#!/bin/bash
# This shell script is to tabulate and search for SR
n=0 # Initial value for Sl.No
next_n=$[$n+1]
read -p "Enter your SR number : " SR
echo -e "$next_nt$SRt$(date)" >> /tmp/cases.txt

1  123   <date>

1 123 <date>
2 456 <date>

#!/bin/bash
# This shell script is to tabulate and search for SR
next_n=$(($(tail -n1 /tmp/cases.txt 2>/dev/null | cut -f1) + 1))
read -p "Enter your SR number : " SR
echo -e "$next_nt$SRt$(date)" >> /tmp/cases.txt

[ -s "/tmp/cases.txt" ] || : > /tmp/cases.txt
next_n=$(expr "$(wc -l < /tmp/cases.txt)" + 1)
read -p "Enter your SR number: " SR
printf '%dt%dt%sn' "$next_N" "$SR" "$(date)" >> /tmp/cases.txt