shell script for showing processes at a specific date - linux

Question

So I've been trying to write a shell script that shows background processes at a specific date. Here is the problem:: the date is a parameter given by the user. I read the date and validated it, but i don't know what command to use. Also, i tried using ps command but to no success. I do not know if my date format is ok either. Here is what I did:
#!/bin/bash
echo "Date dd-mm-yyyy"
read date
if [[ $date =~ ^[0-9]{2}-[0-9]{2}-[0-9]{4}$ ]]
then echo "Date is valid"
else echo "Date is not valid"
fi
Any help would be much appreciated.

Answer 1

if I understand your question you are trying to validate date format in a shell script, so you have to check form of the input using the regex as below :
#! /bin/bash
isDateInvalid()
{
DATE="${1}"
# Autorized separator char ['space', '/', '.', '_', '-']
SEPAR="([ \/._-])?"
# Date format day[01..31], month[01,03,05,07,08,10,12], year[1900..2099]
DATE_1="((([123][0]|[012][1-9])|3[1])${SEPAR}(0[13578]|1[02])${SEPAR}(19|20)[0-9][0-9])"
# Date format day[01..30], month[04,06,09,11], year[1900..2099]
DATE_2="(([123][0]|[012][1-9])${SEPAR}(0[469]|11)${SEPAR}(19|20)[0-9][0-9])"
# Date format day[01..28], month[02], year[1900..2099]
DATE_3="(([12][0]|[01][1-9]|2[1-8])${SEPAR}02${SEPAR}(19|20)[0-9][0-9])"
# Date format day[29], month[02], year[1904..2096]
DATE_4="(29${SEPAR}02${SEPAR}(19|20(0[48]|[2468][048]|[13579][26])))"
# Match the date in the Regex
if ! [[ "${DATE}" =~ "^(${DATE_1}|${DATE_2}|${DATE_3}|${DATE_4})$" ]]
then
echo -e "ERROR - '${DATE}' invalid!"
else
echo "${DATE} is valid"
fi
}
echo
echo "Exp 1: "`isDateInvalid '12/13/3000'`
echo "Exp 2: "`isDateInvalid '12/11/2014'`
echo "Exp 3: "`isDateInvalid '12 01 2020'`
echo "Exp 4: "`isDateInvalid '28-02-2014'`
echo "Exp 5: "`isDateInvalid '12_02_2002'`
echo "Exp 6: "`isDateInvalid '12.10.2099'`
echo "Exp 7: "`isDateInvalid '31/11/2001'`