Bash: if condition to check if actual date exists as string in file?

Question

In a file i have a string like this which is the date of today

Sa 4. Dez

Date format is like this

stringtoday=`date +%Y-%m`

now i wanna use a if condition to check if the date of today exists in this file and if that's the case i want stop the bash script. if the date is not in this file. the script should run. How can i do this?

Answer 1

Something like:

#!/bin/sh

DATE=$(date +%Y-%m)

if grep "$DATE" file >/dev/null; then
    echo yes
else
    echo no
fi

where file is the name of your file should work. It basically uses grep to search for the value of $DATE in file, and branches depending on whether it was found or not (the exit codes of grep indicate this, see man grep "EXIT STATUS" for more information). You can use if grep …; then exit 0; fi to exit the script if the text is found to get the behaviour you want.