Check If The First Argument Is Given
In a shell script, you may want to check if an argument was given. Each argument is referenced numerically with the $
prefix, so the first argument is $1
. To check if the first argument is given, you can use the -z
check.
if [ -z "$1" ]
then
echo "The first argument is missing"
exit 1
fi
The -z
checks if the argument is a zero-length string (so ""
or undefined will be true). If it is missing, then we echo out a message and exit the script. This is how I might fashion a script that requires the first argument.
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