I have a file containing this:

1415602803,LOGIN SUCCESS,AUTH,user2,,,59996,22
1415602807,LOGIN SUCCESS,AUTH,user1,,,48191,22
1415602811,LOGIN FAILED,AUTH,root,,,52506,22
1415602815,LOGIN FAILED,AUTH,user3,,,55750,22

I want to convert the timestamp to a date in this format:

2014-11-10 02:00:03,LOGIN SUCCESS,AUTH,user2,,,59996,22
2014-11-10 02:00:07,LOGIN SUCCESS,AUTH,user1,,,48191,22
2014-11-10 02:00:11,LOGIN FAILED,AUTH,root,,,52506,22
2014-11-10 02:00:15,LOGIN FAILED,AUTH,user3,,,55750,22

How can I do that?

I know this works: perl -pe 's/(\d+)/localtime($1)/e' (from this question) but the output format is Mon Nov 10 02:00:03 2014.

I know this command can convert timestamps into my desired output: date -d@1415602803 +"%F %H:%M:%S", but I couldn't make it work with awk using system("cmd") because of all the quotations and whatnot.

5 Answers 5


Found something here: Stackoverflow - Convert from unixtime at command line.

Came up with this:

awk -F"," '{OFS=","; $1=strftime("%Y-%m-%d %H:%M:%S", $1); print $0}' file
  • -F"," to use a field separator of ,,
  • OFS=","; so that the output fields are also separated by a ,,
  • $1=strftime("%Y-%m-%d %H:%M:%S", $1); to change the value of the first field $1 into the specified format, and
  • print $0; to print the whole line.
  • 2
    awk 'BEGIN{ print strftime("%Y-%m-%d %H:%M:%S", 0) }' gives awk: line 2: function strftime never defined here. Please clarify that NOT EVERY AWK has strftime()! For a solution running in most (all?) AWKs, please use the external date command to stay portable.
    – user62916
    Commented Nov 25, 2014 at 5:37
  • 2
    @yeti, there are a few date implementations that can convert dates between formats as an extension, but how it's done varies completely between the implementations. For instance, the solution given by Costas uses a syntax specific to GNU date. If you want portability, use perl. Commented Aug 17, 2016 at 17:22

Like this perhaps

perl -pe 'use POSIX qw(strftime); s/^(\d+)/strftime "%F %H:%M:%S", localtime($1)/e' 

If you like awk you can use external command date with any date formats

awk -F, -v OFS="," '{("date +%F\ %T -d @"$1)|getline $1}1'
  • +1 for NOT using strftime()!
    – user62916
    Commented Nov 25, 2014 at 5:39
  • 5
    Note that using an external command will incur a severe performance hit, especially noticeable if many thousands of rows are being processed Commented Nov 23, 2015 at 15:58

You can also try:

cat test.txt | sed 's/^/echo "/; s/\([0-9]\{10\}\)/`date -d @\1`/; s/$/"/' | bash

I asked a question 9 months ago that was marked a duplicate of this one. I only just now saw a request to post the answer that worked for me on this question. Here is a link to that question and answer.


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