TIL:
📌 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.
source
📌 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.
source