How can I get a formatted date for a UNIX timestamp from the command line

Question

I have a UNIX timestamp and I'd like to get a formatted date (like the output of date) corresponding to that timestamp.

My attempts so far:

$ date +%s
1282367908
$ date -d 1282367908
date: invalid date `1282367908'
$ date -d +1282367908
date: invalid date `+1282367908'
$ date +%s -d +1282367908
date: invalid date `+1282367908'

I'd like to be able to get output like:

$ TZ=UTC somecommand 1282368345
Sat Aug 21 05:25:45 UTC 2010

Answer 1

On Mac OS X and BSD:

$ date -r 1282368345
Sat Aug 21 07:25:45 CEST 2010
$ date -r 1282368345 +%Y-%m-%d
2010-08-21

with GNU core tools (you have to dig through the info file for that):

$ date -d @1282368345
Sat Aug 21 07:25:45 CEST 2010
$ date -d @1282368345 --rfc-3339=date
2010-08-21

With either, add the -u (standard) option, or pass a TZ=UTC0 environment variable to have the UTC date (TZ=UTC0 defines a timezone called UTC with offset 0 from UTC while the behaviour for TZ=UTC (with no offset) is unspecified (though on most systems would refer to a system-defined timezone also called UTC with offset 0 from UTC)).

Answer 2

After some googling, I found way to do it with the date command only:

$ date --date "Jan 1, 1970 00:00:00 +0000 + 1282367908 seconds"
Sat Aug 21 09:18:28 MSD 2010

Answer 3

This perl one-liner will do it:

$ perl -e 'print scalar localtime $ARGV[0]' 1282367908
Sat Aug 21 09:18:28 2010

Answer 4

With shell builtins:

• zsh (4.1.1 (2003) and above) :

  $ zmodload zsh/datetime
  $ TZ=UTC0 strftime %c 1282368345
  Sat 21 Aug 2010 05:25:45 UTC
  

• ksh93 (ksh93i (2000) and above):

  $ TZ=UTC0 printf '%(%c)T\n' '#1282368345'
  Sat Aug 21 05:25:45 2010
  

• bash (4.2 (2010) and above):

  $ TZ=UTC0 printf '%(%c)T\n' 1282368345
  Sat 21 Aug 2010 05:25:45 UTC
  

In all those, replace %c with the strftime() format you want.

Answer 5

On osx, to have in UTC

date -r "1475737200" -u

Answer 6

Answer to an old question, but I think this might be an improvement if anyone else searches for this. This Bash function works on both Linux and OS X. I have not tested on any other BSD systems. Pass the epoch time as an argument to this function and it will print the RFC-3339 time format.

epochtorfc3339 ()
{
    RFC3339_FORMAT="+%FT%T:::%z"
    EPOCH=$(echo $@ | sed -n "s/.*\([0-9]\{10\}\).*/\1/p");
    if date --version >/dev/null 2>/dev/null; then
        # Linux
        date ${RFC3339_FORMAT} -d "1970-01-01 UTC ${EPOCH} seconds"
        #date -d @${EPOCH} --rfc-3339=seconds
    else
        # OS X/BSD
        date -r ${EPOCH} ${RFC3339_FORMAT}
    fi
}

Answer 7

Another neat example of the rich heritage of modern Unix. This is indeed possible under most BSD variants:

$ TZ=UTC date -r 1282368345
Sat Aug 21 05:25:45 UTC 2010

(BTW your example seems to be off by one second)

Answer 8

For Unix-like environment, the following will work.

# Current UNIXTIME
unixtime() {
  datetime2unixtime "$(date -u +'%Y-%m-%d %H:%M:%S')"
}

# From DateTime（%Y-%m-%d %H:%M:%S）to UNIXTIME
datetime2unixtime() {
  set -- "${1%% *}" "${1##* }"
  set -- "${1%%-*}" "${1#*-}" "${2%%:*}" "${2#*:}"
  set -- "$1" "${2%%-*}" "${2#*-}" "$3" "${4%%:*}" "${4#*:}"
  set -- "$1" "${2#0}" "${3#0}" "${4#0}" "${5#0}" "${6#0}"
  [ "$2" -lt 3 ] && set -- $(( $1-1 )) $(( $2+12 )) "$3" "$4" "$5" "$6"
  set -- $(( (365*$1)+($1/4)-($1/100)+($1/400) )) "$2" "$3" "$4" "$5" "$6"
  set -- "$1" $(( (306*($2+1)/10)-428 )) "$3" "$4" "$5" "$6"
  set -- $(( ($1+$2+$3-719163)*86400+$4*3600+$5*60+$6 ))
  echo "$1"
}

# From UNIXTIME to DateTime format（%Y-%m-%d %H:%M:%S）
unixtime2datetime() {
  set -- $(( $1%86400 )) $(( $1/86400+719468 )) 146097 36524 1461
  set -- "$1" "$2" $(( $2-(($2+2+3*$2/$3)/$5)+($2-$2/$3)/$4-(($2+1)/$3) ))
  set -- "$1" "$2" $(( $3/365 ))
  set -- "$@" $(( $2-( (365*$3)+($3/4)-($3/100)+($3/400) ) ))
  set -- "$@" $(( ($4-($4+20)/50)/30 ))
  set -- "$@" $(( 12*$3+$5+2 ))
  set -- "$1" $(( $6/12 )) $(( $6%12+1 )) $(( $4-(30*$5+3*($5+4)/5-2)+1 ))
  set -- "$2" "$3" "$4" $(( $1/3600 )) $(( $1%3600 ))
  set -- "$1" "$2" "$3" "$4" $(( $5/60 )) $(( $5%60 ))
  printf "%04d-%02d-%02d %02d:%02d:%02d\n" "$@"
}

# Examples
unixtime # => Current UNIXTIME
date +%s # Linux command

datetime2unixtime "2020-07-01 09:03:13" # => 1593594193
date -u +%s --date "2020-07-01 09:03:13" # Linux command

unixtime2datetime "1593594193" # => 2020-07-01 09:03:13
date -u --date @1593594193 +"%Y-%m-%d %H:%M:%S" # Linux command

https://tech.io/snippet/a3dWEQY