[SOLVED] BASH Compare date

linuxiel · 09-23-2014, 02:30 PM

BASH compare list of strings from date
Hi again
I have a list of backup tar files made from the command:
tar -cvpz /mnt/bak/bast-$(date +%Y-%m-%d_%H_%M).tar.gz /home

The list looks like this:

bast-2014-09-08_20_58.tar.gz
bast-2014-09-09_20_20.tar.gz
bast-2014-09-10_20_20.tar.gz
bast-2014-09-11_20_20.tar.gz
bast-2014-09-12_20_20.tar.gz
bast-2014-09-13_20_20.tar.gz
bast-2014-09-14_20_20.tar.gz
bast-2014-09-15_20_20.tar.gz
bast-2014-09-16_20_20.tar.gz
bast-2014-09-17_20_20.tar.gz

I need a bash command or script to work out which is the earliest one?
I looked into sed a bit and got confused with the regex type syntax.
Is there another way or can someone help me with a sed command?

Thanks in advance

suicidaleggroll · 09-23-2014, 02:46 PM

Since it's year-month-day-hour-minute, all you need to do is sort it alphabetically and grab the first one. It would be more complicated if it was month-day-year, but as-is it should be very simple.

linuxiel · 09-23-2014, 02:53 PM

Thanks but im looking for specific syntax. Im not so good at bash yet and a little lost.

I guess I need something like

for a in $(ls /mnt/bak)
do echo "whichever is the earliest of $a"
done

lol I know I know, my scripting sucks.

Habitual · 09-23-2014, 03:19 PM

Quote:

Originally Posted by linuxiel

Thanks but im looking for specific syntax. Im not so good at bash yet and a little lost.

I guess I need something like

for a in $(ls /mnt/bak)
do echo "whichever is the earliest of $a"
done

lol I know I know, my scripting sucks.

How about...

Code:

for a in $(ls -1 /mnt/bak/bast*.gz | sort | head -1); do  echo "$a" is the earliest ; done

I'm a terrible hack at bash scripting so this is mere butchery.
Expect better answers 1 minute after I Submit Reply.

output:

Code:

bast-2014-09-08_20_58.tar.gz is the earliest

naitso · 09-23-2014, 03:22 PM

ls -lt /mnt/bak/ | head -n 1

suicidaleggroll · 09-23-2014, 03:55 PM

Quote:

Originally Posted by naitso

ls -lt /mnt/bak/ | head -n 1

It's a bad idea to assume the file's timestamp is the time it was originally created. backups get moved and copied all the time, you can't rely on that.

---------- Post added 09-23-14 at 02:56 PM ----------

Quote:

Originally Posted by linuxiel

Thanks but im looking for specific syntax. Im not so good at bash yet and a little lost.

I guess I need something like

for a in $(ls /mnt/bak)
do echo "whichever is the earliest of $a"
done

lol I know I know, my scripting sucks.

You mean something like

Code:

echo $(ls /mnt/bak/bast* | head -1) is the earliest file

?

ls already sorts the output alphabetically, so all you need is a "head -1" to grab the first one.

linuxiel · 09-23-2014, 07:00 PM

Thanks guys, that worked.

I marked as solved, but secondary if you feel like it: what If I wanted to choose a particular date.

listing the directory, giving a prompt to chose a date?

doesnt matter if theres no replys to this, I might have a play around a bit more myself