Unable to read the timestamp of Zsh history

Question

Problem: to understand the following timestamp

1241036430

at ~/.history

: 1241036336:0;vim ~/.zshrc
: 1241036379:0;vim ~/bin/HideTopBar
: 1241036421:0;ls
: 1241036430:0;cat ~/.history

when I have

setopt EXTENDED_HISTORY
HISTFILE=~/.history

in .zshrc.

How can you read the timestamp?

Answer 1

This simple util, called localtime is gold for reading files with timestamps:

#!/usr/bin/perl
# http://perl.plover.com/classes/mybin/samples/source/localtime

if ($ARGV[0] eq '-f') {
  *show_localtime = \&show_localtime_list;
  shift;
}

if (@ARGV) {
  for (@ARGV) {
    print show_localtime($_), "\n";
  }
} else {
  while (<>) {
    s/^(\d+)/show_localtime($1)/e;
    print;
  }
}


sub show_localtime {
  my $t = shift;
  scalar localtime $t;
}

sub show_localtime_list {
  my $t = shift;
  my @a = localtime $t;
  "@a\n"
}

• (There is also a little presentation :))

It handles lots of cases, and seem to understand both timestamps in seconds and mini-seconds, etc.

$ localtime < ~/.histfile
<snip>
: Sat Sep 17 05:55:17 2016:0;cat localtime

Answer 2

Try history -d. Or just type history - and press control-D to get all the various options:

% history -
-D  -- print elapsed times
-E  -- dd.mm.yyyy format time-stamps
-d  -- print time-stamps
-f  -- mm/dd/yyyy format time-stamps
-i  -- yyyy-mm-dd format time-stamps
-m  -- treat first argument as a pattern
-n  -- suppress line numbers
-r  -- reverse order of the commands

Answer 3

You can display the whole history with human-readable timestamps using this one-liner taken from an answer on the zsh mailing list:

perl -lne 'm#: (\d+):\d+;(.+)# && printf "%s :: %s\n",scalar localtime $1,$2' $HISTFILE

I would recommend piping the output to a pager (less for example) to make it more readable.

Answer 4

Adendum: You can use the history command itself to translate timestamps found in saved history files as well:

The options to the history command as explained by Nicholas Riley apply just as well to saved history files, so history -d < historyfile (or any of the other options) translates the timestamps just fine.

This comes in handy if you're using more than just one history file - I've setup zsh to keep one history file per pty to avoid mixing up histories from shells running in parallel on the same system (since usually each window/screen/... is particular to a certain task, and so the histories emerging from normal use end up sort of themed).

Answer 5

: 1241036430:0;cat ~/.history

‘: <beginning time>:<elapsed seconds>;<command>’.

extendedhistory - saves the time in seconds. The beginning time is since the epoch.

source: http://zsh.sourceforge.net/Doc/Release/Options.html#index-EXTENDEDHISTORY