I have a shell script which is automatically ran each morning which appends that days results to a text file. The file should have todays date on the first column followed by results separated by commas. I use the command date +%x to get the day in the required format (dd/mm/yy). However on one computer date +%x returns mm/dd/yyyy ( any idea why this is the case?). I then sort the data in the file in date order.
Here is a snippet of such a text file
29/11/12,9654.80,194.32,2.01,7.19,-7.89,7.65,7.57,3.98,9625.27,160.10,1.66,4.90,-4.79,6.83,4.84,3.54
03/12/12,5184.22,104.63,2.02,6.88,-6.49,7.87,6.67,4.10,5169.52,93.81,1.81,5.29,-5.45,7.87,5.37,4.10
04/12/12,5183.65,103.18,1.99,6.49,-6.80,8.40,6.66,4.38,5166.04,95.44,1.85,6.04,-6.49,8.40,6.28,4.38
11/07/2012,5183.65,102.15,1.97,6.78,-6.36,8.92,6.56,4.67,5169.48,96.67,1.87,5.56,-6.10,8.92,5.85,4.67
07/11/2012,5179.39,115.57,2.23,7.64,-6.61,8.83,7.09,4.62,5150.17,103.52,2.01,7.01,-6.08,8.16,6.51,4.26
11/26/2012,5182.66,103.30,1.99,7.07,-5.76,7.38,6.37,3.83,5162.81,95.47,1.85,6.34,-5.40,6.65,5.84,3.44
11/30/2012,5180.82,95.19,1.84,6.51,-5.40,7.91,5.92,4.12,5163.98,91.82,1.78,5.58,-5.07,7.05,5.31,3.65
Is it possible to change the date format for the latter four lines to the correct date format using awk or sed? I only wish to change the date format for those in the form mm/dd/yyyy to dd/mm/yy.
It looks like you're using two different flavors (versions) of date. To check which versions you've got, I think GNU date accepts the --version flag whereas other versions, like BSD/OSX will not accept this flag.
Since you may be using completely different systems, it's probably safest to avoid date completely and use perl to print the current date:
perl -MPOSIX -e 'print POSIX::strftime("%d/%m/%y", localtime) . "\n"'
If you are sure you have GNU awk on both machines, you could use it like this:
awk 'BEGIN { print strftime("%d/%m/%y") }'
To fix the file you've got, here's my take using GNU awk:
awk '{ print gensub(/^(..\/)(..\/)..(..,)/, "\\2\\1\\3", "g"); next }1' file
Or using sed:
sed 's/^\(..\/\)\(..\/\)..\(..,\)/\2\1\3/' file
Results:
29/11/12,9654.80,194.32,2.01,7.19,-7.89,7.65,7.57,3.98,9625.27,160.10,1.66,4.90,-4.79,6.83,4.84,3.54
03/12/12,5184.22,104.63,2.02,6.88,-6.49,7.87,6.67,4.10,5169.52,93.81,1.81,5.29,-5.45,7.87,5.37,4.10
04/12/12,5183.65,103.18,1.99,6.49,-6.80,8.40,6.66,4.38,5166.04,95.44,1.85,6.04,-6.49,8.40,6.28,4.38
07/11/12,5183.65,102.15,1.97,6.78,-6.36,8.92,6.56,4.67,5169.48,96.67,1.87,5.56,-6.10,8.92,5.85,4.67
11/07/12,5179.39,115.57,2.23,7.64,-6.61,8.83,7.09,4.62,5150.17,103.52,2.01,7.01,-6.08,8.16,6.51,4.26
26/11/12,5182.66,103.30,1.99,7.07,-5.76,7.38,6.37,3.83,5162.81,95.47,1.85,6.34,-5.40,6.65,5.84,3.44
30/11/12,5180.82,95.19,1.84,6.51,-5.40,7.91,5.92,4.12,5163.98,91.82,1.78,5.58,-5.07,7.05,5.31,3.65
This should work: sed -re 's/^([0-9][0-9])\/([0-9][0-9])\/[0-9][0-9]([0-9][0-9])(.*)$/\2\/\1\/\3\4/'
It can be made smaller but I made it so it would be more obvious what it does (4 groups, just switching month/day and removing first two chars of the year).
Tip: If you don't want to cat the file you could to the changes in place with sed -i. But be careful if you put a faulty expression in you might end up breaking your source file.
NOTE: This assumes that IF the year is specified with 4 digits, the month/day is reversed.
This below command will do it.
Note:No matter how many number of lines are present in the file.this will just change the last 4 lines.
tail -r your_file| awk -F, 'NR<5{split($1,a,"/");$1=a[2]"/"a[1]"/"a[3];print}1'|tail -r
Well i could figure out some way without using pipes and using a single awk statement and this solution does need a tail command:
awk -F, 'BEGIN{cmd="wc -l your_file";while (cmd|getline tmp);split(tmp,x)}x[1]-NR<=4{split($1,a,"/");$1=a[2]"/"a[1]"/"a[3];print}1' your_file
Another solution:
awk -F/ 'NR<4;NR>3{a=$1;$1=$2;$2=a; print $1"/"$2"/" substr($3,3,2) substr($3,5)}' file
Using awk:
$ awk -F/ 'NR>3{x=$1;$1=$2;$2=x}1' OFS="/" file
By using the / as the delimiter, all you need to do is swap the 1st and 2nd fields which is done here using a temporary variable.
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).
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