date
[OPTION]... [+FORMAT]
date [-u|--utc|--universal]
[MMDDhhmm[[CC]YY][.ss]]
Step 2
Convert seconds since the epoch (1970-01-01 UTC) to a date
$ date --date=’@2147483647’
Show the time on the west coast of the US (use tzselect(1) to find TZ)
$ TZ=’America/Los_Angeles’ date
Show the local time for 9AM next Friday on the west coast of the US
$ date --date=’TZ="America/Los_Angeles" 09:00 next Fri’
date ##What does it do ? It displays the system's current date, time, time standard and year ##Ouput Wed Dec 25 13:42:54 GMT 2013example added by an anonymous user
I kept experimenting till I figured out that vim was expanding the "%" character. So just escape "\%" and every thing works as I expected.
:r!date "+\%F"
2012-07-20
Now I can put dates into files Like I would like to
:r!date "+\%F" -d "-2 day"
2012-07-18
watch is meant for output to a display. If you
simply want to run a command every X seconds then you should just
use a delay loop for that.
while true ; do somecommand ; sleep 2 ; done
Check your timezone. hwclock may return GMT time,
whileas date returns local time, afaik.
Can't be done in just Bash, but if you have Perl:
use POSIX;
my ($jday, $year) = (100, 2011);
# Unix time in seconds since Jan 1st 1970
my $time = mktime(0,0,0, $jday, 0, $year-1900);
# same thing as a list that we can use for date/time formatting
my @tm = localtime $time;
my $yyyymmdd = strftime "%Y%m%d", @tm;
This example is from http://www.pixelbeat.org/cmdline.html#dates
It gives the local time corresponding to 9AM on the west coast of the US, accounting for differing day light savings transitions.
date --date='TZ="America/Los_Angeles" 09:00 next Fri'
Use tzselect to get the TZ. The PST format is ambiguous. IST = Indian Standard Time and Irish Summer Time for example.
I think this article has an answer to your question: Notify userspace about time changes. But please note that the patch mentioned in the article is quite recent, so you have to check your linux kenel vesrion first.
If your kernel does not support userspace notification mechanism, then you can implement the following algorithm (in pseudocode):
time = gettimeofday()
loop:
sleep 1 second
new_time = gettimeofday()
if (time_diff(new_time, time) > 2 seconds) then
alert System time has changed by an external user/process!
time = new_time
goto loop
Hope this helps.
This Perl script should do what you need (assuming you don't need precision to the 10-6 of a second):
#!/usr/bin/perl -w
use strict;
use Math::Round;
## Get current date (epoch)
my $date=time();
## Get the seconds offset, rounding to the nearest second
my $ntp=nearest(0.1,`ntpdate -q $ARGV[0] | gawk '(\$NF~/sec/){print \$(NF-1)}'`);
## Get the server's time
my $ntp_date=$date+$ntp;
## Convert to human readable and print
print "The time according to server $ARGV[0] is " . localtime($ntp_date) . "\n";
Save the script as check_ntp.pl and run it with the server as an argument:
perl ./check_ntp.pl my.ntp.server
You can change your time zone by doing # dpkg-reconfigure
tzdata. I'm not sure how you would change the time by an
arbitrary value, though.
Here's an idea: Every time a backup is run, the backup script
records the current date by touching a file. The
next time the backup runs, it uses the previous backup's
datestamp file as the argument to tar -N. For
example, in a shell script, the logic could look like this:
# Begin the latest backup run now.
touch /backups/new-backup-time
tar -N /backups/prev-backup-time -c ... ...
# Save the latest backup time for the next run.
mv /backups/new-backup-time /backups/prev-backup-time
This depends on the fact that the tar -N option can
either be a date, OR it can be the pathname of a file whose data
modification time specifies the date.
You need to change the timezone.
To do it system-wide, symlink /etc/localtime to
the apropriate file in /usr/share/zoneinfo. For
example:
ln -sf /usr/share/zoneinfo/Europe/Paris /etc/localtime
In CentOS, you might need to also edit
/etc/sysconfig/clock.
To change the timezone just for the current user, set $TZ instead:
export TZ="Europe/Paris"
Note that date -u must always
return correct UTC time.
cp /usr/share/zoneinfo/Asia/Calcutta /etc/localtime
or
cp /usr/share/zoneinfo/Asia/Colombo /etc/localtime
Some distribution provide utilities for that like
dpkg-reconfigure tzdata, tzselect, etc.
The problem is that ` marks are used to denote commands who's output should be substituted in your command... so your command is actually three commands:
Command #1 outputs nothing, and command #2 results in the "Command not found" error, because -1308741881 is not a valid command, then outputs nothing either.
Then finally the third command runs, with those replacements and looks like this:
find . -mtime -date
And since "-date" isn't a valid time, it complains about that, too, saying "illegal time value"
The underlying problem is that you're trying to use nested `` marks, which the shell interprets as two separate commands.
A better way to express what you want is this (for bash):
find . -mtime -$(echo $(date +%s-1308741881) | bc)s
And for csh:
set now=`date +%s-1308741881`; set date=`echo $now | bc`s; find . -mtime -$date
And possibly for other shells (untested):
NOW=`date +%s-1308741881`; DATE=`echo $NOW | bc`; find . -mtime -${DATE}s
P.S. I don't think this does what you expect... your date command is returning a number of seconds, but -mtime expects a number of days as input. I'm guessing you'll probably want to adjust your date command accordingly.
Use the following syntax to set new data and time:
date --set="STRING"
Are you sure there isn't a problem with how you are executing the command within the script, maybe missing quotes or something of that nature? I cannot reproduce your problem.
$ date
Tue Jul 31 19:08:50 EDT 2012
$ date -d "next tuesday"
Tue Aug 7 00:00:00 EDT 2012
$ date -d "this tuesday"
Tue Jul 31 00:00:00 EDT 2012
$ date --version
date (GNU coreutils) 8.5
Display the
current time in the given FORMAT, or set the system date.
-d, --date=STRING
display time described by STRING, not ’now’
-f, --file=DATEFILE
like --date once for each line of DATEFILE
-I[TIMESPEC], --iso-8601[=TIMESPEC]
output date/time in ISO 8601 format. TIMESPEC=’date’ for date only (the default), ’hours’, ’minutes’, ’seconds’, or ’ns’ for date and time to the indicated precision.
-r, --reference=FILE
display the last modification time of FILE
-R, --rfc-2822
output date and time in RFC 2822 format. Example: Mon, 07 Aug 2006 12:34:56 -0600
--rfc-3339=TIMESPEC
output date and time in RFC 3339 format. TIMESPEC=’date’, ’seconds’, or ’ns’ for date and time to the indicated precision. Date and time components are separated by a single space: 2006-08-07 12:34:56-06:00
-s, --set=STRING
set time described by STRING
-u, --utc, --universal
print or set Coordinated Universal Time
--version
output version information and exit
FORMAT controls the output. Interpreted sequences are:
By default, date pads numeric fields with zeroes. The following optional flags may follow ’%’:
After any flags comes an optional field width, as a decimal number; then an optional modifier, which is either E to use the locale’s alternate representations if available, or O to use the locale’s alternate numeric symbols if available.
Copyright © 2012 Free Software Foundation, Inc. License GPLv3+:
GNU GPL version 3 or later
<http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute
it. There is NO WARRANTY, to the extent permitted by law.
The --date=STRING is a mostly free format human readable date string such as "Sun, 29 Feb 2004 16:21:42 -0800" or "2004-02-29 16:21:42" or even "next Thursday". A date string may contain items indicating calendar date, time of day, time zone, day of week, relative time, relative date, and numbers. An empty string indicates the beginning of the day. The date string format is more complex than is easily documented here but is fully described in the info documentation.
Report date bugs to bug-coreutils[:at:]gnu[:dot:]org
GNU coreutils home page:
<http://www.gnu.org/software/coreutils/>
General help using GNU software:
<http://www.gnu.org/gethelp/>
Report date translation bugs to
<http://translationproject.org/team/>
The full documentation for date is maintained as a Texinfo manual. If the info and date programs are properly installed at your site, the command
info coreutils 'date invocation'
should give you access to the complete manual.
Written by David MacKenzie.