Running a ShellScript with flags for the command line arguments - bash

Question

The code below which i have developed yesterday , takes either a file(x.txt) or space delimited numbers(434 435 436 437 ) as input and the pushes the data fron either case in an array and loops through.
Syntax: shtest.sh 434 435 436 or sh test.sh x.txt
MYFILE=$1 ;
OLDIFS=$IFS;
IFS=' ';
if [ -f "$MYFILE" ]; then
testCases=($(cat $MYFILE));
else
testCases=($#);
fi
for testCase in "${testCases[#]}"
do
echo "Running Testcases $testCase"
done
The way i want to do it to make it less error prone
I would like to actually have a flag while running the above script with a file as a paramenter
sh test.sh -f myFile.txt
or Can be run with -t flasg with numbers as the arguments
sh test.sh -t 434 435 436
if Both -f and -t exist, then i have to check and throw an error
ex: sh test.sh -f myFile.sh -t 343 435 435 or
sh test.sh -t 343 435 435 -f myFile.sh
I have started working on Shell Scripting just yesterday, and iam really short of how to do it syntactically
Finally , If we have flagged file or Flagged number arguments (No Unfalgged at all) , would the code below work or would that have any issues
Syntax:
sh test.sh -f myFile.txt #should work
sh test.sh -t 443 444 443 443 # should work
sh test.sh -f myFile.txt -t 443 444 443 443 # should fail
isFile=0;
isTest=0;
while getopts ":f:c:t:" opt; do
case $opt in
f)
echo "-f was triggered, Parameter: $OPTARG" >&2
testCases=($(cat $OPTARG));
isFile=1;
;;
t)
# testCases=($#);
multi+=("$OPTARG")
for val in "${multi[#]}"; do
echo " - $val"
done
;;
c)
echo "-c was triggered, Parameter: $OPTARG" >&2;
isTest=1;
;;
\?)
echo "Invalid option: -$OPTARG" >&2
exit 1
;;
:)
echo "Option -$OPTARG requires an argument." >&2
exit 1
;;
esac
done
# Exit if both flags are sent
if [ isTest==1 && isFile==1 ]; then
{
echo "Exiting";
}
fi
#if the flag is not avaiable, the store the orphan numbers (Command Line Arguments)
for testCase in "${testCases[#]}"
do
echo "Running Testcases $testCase"
done
Please advice and any help is appreciated.
Thanks
Tejas

Answer 1

After the while getopts loop, add:
shift $(($OPTIND - 1))
if [ $isFile = 0 ] && [ $# = 0 ]
then
echo "$0: must specify file (-f file) or numbers" >&2
exit 1
fi
I assume that you have isFile=0 before your loop. If you don't set it explicitly, you could inherit an environment variable that the user set accidentally. Always be careful that you don't accidentally use environment variables from the code that invokes your script.