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