Append date to filename in linux

Question

I want add the date next to a filename ("somefile.txt"). For example: somefile_25-11-2009.txt or somefile_25Nov2009.txt or anything to that effect

Maybe a script will do or some command in the terminal window. I'm using Linux(Ubuntu).

Thanks in advance.

oh i almost forgot to add that the script or command should update the filename to a new date everytime you want to save the file into a specific folder but still keeping the previous files. So there would be files like this in the folder eventually: filename_18Oct2009.txt , filename_9Nov2009.txt , filename_23Nov2009.txt

Answer 1

You can use backticks.

$ echo myfilename-"`date +"%d-%m-%Y"`" 

Yields:

myfilename-25-11-2009 

Answer 2

There's two problems here.

1. Get the date as a string

This is pretty easy. Just use the date command with the + option. We can use backticks to capture the value in a variable.

$ DATE=`date +%d-%m-%y`  

You can change the date format by using different % options as detailed on the date man page.

2. Split a file into name and extension.

This is a bit trickier. If we think they'll be only one . in the filename we can use cut with . as the delimiter.

$ NAME=`echo $FILE | cut -d. -f1 $ EXT=`echo $FILE | cut -d. -f2` 

However, this won't work with multiple . in the file name. If we're using bash - which you probably are - we can use some bash magic that allows us to match patterns when we do variable expansion:

$ NAME=${FILE%.*} $ EXT=${FILE#*.}  

Putting them together we get:

$ FILE=somefile.txt              $ NAME=${FILE%.*} $ EXT=${FILE#*.}  $ DATE=`date +%d-%m-%y`          $ NEWFILE=${NAME}_${DATE}.${EXT} $ echo $NEWFILE                  somefile_25-11-09.txt                          

And if we're less worried about readability we do all the work on one line (with a different date format):

$ FILE=somefile.txt   $ FILE=${FILE%.*}_`date +%d%b%y`.${FILE#*.} $ echo $FILE                                  somefile_25Nov09.txt