Shell scripting help, time/date manipulation

enine · 02-25-2009, 09:15 PM

I'm still learning scripting and need some direction on modifying time/date strings.

Some background, I learned early on that most unix/linux file system don't track the file creation date/time but it doesn't matter anyway since something as simple as e-mailing a file invalidates it. I learned about metadata inside files such as the jpg exif and similar. Now I keep a lot of information electronic and sometimes have to scan things and am working on using the metadata to track some info about what I've scanned. This leads me to todays script.

Using xscanimage I get a .pnm which I convert to a .tif then add in the metadata with a script something like this:

Code:

exiftool -IFD0:ModifyDate="2009:02:11 22:24:14" *.tif
exiftool -IFD0:ImageDescription="Receipt" *.tif

Now I'm trying to automate this a bit more by taking from the konqueror service menu for the convert to .tif I make my script

Code:

convert %f "`echo %f | perl -pe 's/\.[^.]+$//'`.tif"

I want to take the output of

Code:

 stat -c %y %f

which looks like

Code:

2009-02-11 22:24:14.000000000 -0500

and feed it into the command

Code:

exiftool -IFD0:ModifyDate="2009:02:11 22:24:14" %f.tif

So what happens is the original .pnm gets a time and date set on the file system when its written by xscanimage. I then use the script called by the Konqueror service menu which converts to .tif and in addition take the file system date/time and feeds it into exiftool to set it in the file's metadata therefore preserving it.
My difficulty lies in converting the format of the time and date from the output of one to the proper format for the other and passing the variable through as I don't sting stat will take %f like the original service menu script did since stat uses % as its option delimiter.

Of course any suggestions of other tools that may do this easier will help too. I'm setting more than just the time/date, I set other fields that save things like the scanner make and model, and descriptions. For example I have a IRA account that the bank doesn't allow electronic statements so I have to scan the paper ones. I then put what they are in the descriptions.
I use the same for my pictures, instead of trying to rename 100 .jpg's from a family vacation I used exiftool and wildcards to edit comments into several at once.

jlinkels · 02-26-2009, 05:24 AM

I am not sure I fully understand your problem (it is early in the morning) but I think your it is about converting one date format to the other. For date format problems date is you friend.

With "-d" you can feed ANY readable date into date and get an output in any format.

Code:

jlinkels@jlinkels-lt:~$ date -d "2009-02-11 22:24:14.000000000 -0500"
Thu Feb 12 03:24:14 GMT 2009

or:

Code:

jlinkels@jlinkels-lt:~$ date -d "2009-02-11 22:24:14.000000000 -0500" +%Y-%m-%d
2009-02-12

You can assign the string to a variable:

Code:

jlinkels@jlinkels-lt:~$ mydate=$(date -d "2009-02-11 22:24:14.000000000 -0500" +%Y-%m-%d)
jlinkels@jlinkels-lt:~$ echo $mydate
2009-02-12

You can use $mydate in a shell script in any command.

jlinkels

Quigi · 02-26-2009, 02:45 PM

Quote:

Originally Posted by enine

My difficulty lies in converting the format of the time and date from the output of one to the proper format for the other and passing the variable through as I don't sting stat will take %f like the original service menu script did since stat uses % as its option delimiter.

Yup, date is your friend. Don't take the output of stat, so you don't have to convert formats.

In bash (and most other shells), $ does variable substituion. Try it out:

Code:

file=some_image.tif
echo $file
date -r $file "+%F %T"

Of course, substitute the name of some image of yours. You can use it like this:

Code:

exiftool -IFD0:ModifyDate=`date -r $file "+%F %T"` $file

You lost me where you don't sting.

Maybe rephrase that part?
/Quigi

enine · 02-26-2009, 07:26 PM

Ok, looks like date can do the conversion. I need the date of the file, not the data currently so I still need to stat the file to get its date then convert.

colucix · 02-26-2009, 07:38 PM

Quote:

Originally Posted by enine

Ok, looks like date can do the conversion. I need the date of the file, not the data currently so I still need to stat the file to get its date then convert.

You can use the -r option of date to retrieve the time of last modification of a file instead of the current time, as previously shown by Quigi.

enine · 02-26-2009, 08:04 PM

Ahh, sorry, I was thinking it was pulling the system date, not the file date, I'll try again.
Thanks