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

Info/Summary

With bash scripting you can enclose commands in back ticks or parantheses. This works great for labling files, the following wil create a file name with the date appended to it.

Methods

Backticks -

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

$(parantheses) - :

$ echo myfilename-$(date +"%d-%m-%Y")

Example Usage:

echo "Hello World" > "/tmp/hello-$(date +"%d-%m-%Y").txt"

(creates text file '/tmp/hello-28-09-2022.txt' with text inside of it)

Note, in Linux quotes are your friend, best practice to enclose the file name to prevent issues with spaces and such in variables.

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

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

You can add date next to a filename invoking date command in subshell.

date command with required formatting options invoked the braces of $() or between the backticks (`…`) is executed in a subshell and the output is then placed in the original command.

The $(...) is more preferred since in can be nested. So you can use command substitution inside another substitution.

Solutions for requests in questions

$ echo somefile_$(date +%d-%m-%Y).txt
somefile_28-10-2021.txt

$ echo somefile_$(date +%d%b%Y).txt
somefile_28Oct2021.txt

The date command comes with many formatting options that allow you to customize the date output according to the requirement.

• %D – Display date in the format mm/dd/yy (e.g. : 10/28/21)
• %Y – Year (e.g. : 2021)
• %m – Month (e.g. : 10)
• %B – Month name in the full string format (e.g. : October)
• %b – Month name in the shortened string format (e.g. : Oct)
• %d – Day of month (e.g. : 28)
• %j – Day of year (e.g. : 301)
• %u – Day of the week (e.g. : 4)
• %A – Weekday in full string format (e.g. : Thursday)
• %a – Weekday in shortened format (e.g. : Thu)

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!!

I use it in raspberry pi, and the first answer doesn't work for me, maybe because I typed wrong or something? I don't know. So I combined the above answers and came up with this:

now=$(date +'%Y-%m-%d')
geany "OptionalName-${now}.txt"

That if you want to use geany or anything else

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