UNIX for Dummies Questions & Answers

# Checks for valid number of arguments
# Exits program with return code of 1
if [ $# -ne 1 ]; then
        echo "Invalid number of arguments; supports only one argument"

        exit 1
fi

# Checks for valid argument
echo $1 | egrep -s "^[+|-]?[0-9]+$"

# If argument is valid then return its value
# Exits program with return code of 0
if [ $? -eq 0 ]; then
        # Removes a leading '+' sign if there is one
        tr -d '+' $1
        echo $1

        exit 0
# If argument is invalid then return an error message
# Exits program with return code of 2
else
        echo "Invalid operand: $1"

        exit 2
fi

# Checks for valid argument
echo $1 | egrep -s "(^[\+]?[0-9]+$)|(^[-]?[0-9]+$)"

# If argument is valid then return its value
# Exits program with return code of 0
if [ $? -eq 0 ]; then
        # Removes a leading '+' sign if there is one
        echo $1 | tr -d "+" " "

        exit 0

# If argument is invalid then return an error message
# Exits program with return code of 1
else
        echo "Invalid operand: $1"

        exit 1
fi