I want to write a script that reads my input (for example if my script is called "check", then I would type "check 9 4 1993" and that input would go through the cal command and will check through the calendar whether it is a valid date or not).
My idea below is that if the input that goes through the cal command gives an error it will mean that it's not a valid date, and vice-versa if there's no error than the date is valid. I do realize there's something terribly wrong with this draft (I can't figure out how to make it so that my input will go through the cal command), but I will appreciate some suggestions. Here's the draft anyways:
#!/bin/bash day=$1; month=$2; year=$3 day=$(echo "$day" | bc) month=$(echo "$month" | bc) year=$(echo "$year" | bc) cal $day $ month $year 2> /dev/null if [[$? -eq 0 ]]; then echo "This is a valid date" else echo "This is an invalid date" fi