I have a string which described the active directory expiration date of my account. I want to use/parse this string and do something when expiration date is coming soon. Now I have a problem extracting the date-part of the complete string. The string is:
Password expires 1-4-2015 15:41:05
I want to extract 1-4-2014 from it, but when the date is 20-12-2015, the mechanism should also work. Unfortunately I'm unable to config the source system so that it outputs leading zero's. I have tried piping the string to cut -c30-39, but obviously this does not work with strings which are in total longer (like 20-12-2015).
So I'm looking for a more robust solution, something like extracting extracting until the last 4 digits AFTER the 2nd --character.
You could use grep,
$ echo 'Password expires 1-4-2015 15:41:05' | grep -o '\b[0-9]\{1,2\}-[0-9]\{1,2\}-[0-9]\{4\}\b'
1-4-2015
$ echo 'Password expires 20-12-2015 15:41:05' | grep -o '\b[0-9]\{1,2\}-[0-9]\{1,2\}-[0-9]\{4\}\b'
20-12-2015
To grep only the year.
$ echo 'Password expires 20-12-2015 15:41:05' | grep -oP '^(?:[^-]*-){2}\K\d{4}\b'
2015
To get only the day
$ echo 'Password expires 1-4-2015 15:41:05' | grep -oP '\b[0-9]{1,2}(?=-[0-9]{1,2}-[0-9]{4}\b)'
1
To get only the month
$ echo 'Password expires 1-4-2015 15:41:05' | grep -oP '\b[0-9]{1,2}-\K[0-9]{1,2}(?=-[0-9]{4}\b)'
4