shell script - reading from standard input versus a file

Question

I have the following input file in.txt:

a
b
c
a
b
c

I have the following script test.sh:

# display unique rows
while read line
do 
  echo $line
done < $(cat "$@" | sort | uniq) 

# display all rows
while read line
do 
  echo $line
done < $(cat "$@") 

I know I can run the script using:

sh test.sh in.txt

I also know I can run it using standard input instead of a file. However, this only supplies input to the first while loop. How can I supply the input to both loops without typing the input twice?

Answer 1

This script accepts stdin and produces both outputs:

#!/bin/sh

echo "Unique rows:"
tee ~/tmpfile$$ | sort | uniq

echo "All Rows:"
cat ~/tmpfile$$

rm ~/tmpfile$$