[linux] Append date to filename in linux

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

You can use backticks.

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

Yields:

myfilename-25-11-2009

cp somefile somefile_`date +%d%b%Y`

a bit more convoluted solution that fully matches your spec

echo `expr $FILENAME : '\(.*\)\.[^.]*'`_`date +%d-%m-%y`.`expr $FILENAME : '.*\.\([^.]*\)'`

where first 'expr' extracts file name without extension, second 'expr' extracts extension

I use this script in bash:

#!/bin/bash

now=$(date +"%b%d-%Y-%H%M%S")
FILE="$1"
name="${FILE%.*}"
ext="${FILE##*.}"

cp -v $FILE $name-$now.$ext

This script copies filename.ext to filename-date.ext, there is another that moves filename.ext to filename-date.ext, you can download them from here. Hope you find them useful!!

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