Unix/Linux Go Back    


UNIX for Beginners Questions & Answers If you're not sure where to post a Unix or Linux question, post it here. All unix and Linux beginners welcome in this forum!

General Purpose Date Script

UNIX for Beginners Questions & Answers


Reply    
 
Thread Tools Search this Thread Display Modes
    #1  
Old Unix and Linux 10-25-2013   -   Original Discussion by Corona688
Corona688's Unix or Linux Image
Corona688 Corona688 is offline Forum Staff  
Mead Rotor
 
Join Date: Aug 2005
Last Activity: 13 December 2017, 10:16 AM EST
Location: Saskatchewan
Posts: 22,546
Thanks: 1,159
Thanked 4,286 Times in 3,955 Posts
General Purpose Date Script

There must be thousands of one-off solutions scattered around this forum. GNU Date is so handy because it's general but if they're asking they probably don't have it. We have some nice scripts but they tend to need dates formatted in a very particular way.

This is a rough approximation which can handle -d "something - 3 days" kind of requests. It is not nearly so robust as GNU Date.

I'm trying to avoid needing nonstandard modules. Comments, criticism?


Code:
#!/usr/bin/perl

use POSIX;
use strict;
use warnings;

my $cmdstr="%Y-%m-%d %H:%M:%S";		# see strftime
my ($input, $arg, $sign, $ref,$offset,$quiet,$n)=("", undef, 0, time,0,0,0);
# $lt[SEC] is seconds, etc.  See perldoc -f localtime
use constant {	SEC=>0,	MIN=>1,	HOUR=>2,DAY=>3,	MON=>4,	YEAR=>5,WDAY=>6 };
# Times stored in the format of 'perldoc -f localtime'.
# In the case of @changed, only elements that were altered in @lt are 
# set,other values are undefined.
my (@lt, @changed);
# Lookups for mon/tues/wed jan/feb/mar names into day and month numbers
my (%month, %days);
# Lookup table to convert 'year' into a number of seconds, etc
my %mult=("second" => 1, "seconds" => 1, "minute" => 60, "minutes" => 60,
	"hour" => 3600, "hours" => 3600, "day" => 86400, "days" => 86400,
	"week" => 604800, "weeks" => 604800,
	"year" => 31536000, "years" => 31536000 );

# Parse commandline arguments
while(defined($arg=shift)) {
        if($arg =~ /^--date=(.*)/)  {       $input=$1;                  }
        elsif($arg eq "-d")         {       $input=shift;               }
        elsif($arg =~/^\+(.*)/)     {       $cmdstr=$1;                 }
	elsif($arg eq "-q")	    {	    $quiet=1;		        }
        elsif(($arg eq "-r") || ($arg =~ /^--reference=(.*)$/))
	{
		if(defined($1))	{ $arg=$1; }
		else		{ $arg=shift; }
	        my ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,
        	       $atime,$mtime,$ctime,$blksize,$blocks)
	               = stat($arg);

	        defined($dev) || die("No such file $arg");

		$ref=$mtime;
	}
        elsif($arg =~/^(-h|--help|--version)$/) {
                print STDERR <<"EOT";
date.pl v0.1.0, Tyler Montbriand, 2016.  Free PERL date calc/converter.
 -d "time string"       string like "YYYYMMDD", "YYYY/MM/DD",
                        "HHMMSS", "HH:MM:SS", "\@epoch", "- 3 days",
			"Mar 3 2016 1:16:09 AM", 
                        etc.  You can string them together, like
                        "\@1343322750 - 3 days".

 -r /path/to/file       Show mtime of the given file, not current time.

 +"formatstring"        Give strftime this format string instead of the
                        default "%Y-%m-%d %H:%M:%S".  See 'man strftime'

 -q			date.pl warns you when given conflicting
			information, i.e. feb 29 not on a leap year.
			It also warns you when input isn't understood.
			-q suppesses this.
Examples:
date.pl                         # current time in YYYY-MM-DD HH:MM:SS
TZ="UTC" ./date.pl              # Use an alternate time zone
date.pl +"%a %b %d %Y %r"       # Like Thu Jan 16 2014 12:58:59 PM
date.pl -d "+ 3 days"           # Current time plus three days
date.pl -d "\@1343322750"       # exact time in epoch seconds
date.pl -d "2013/01/02 12:00:00"# exact time in YYYYMMDD HHMMSS
date.pl -d "9am"                # Today at 9am
date.pl -d "last week + 5 minutes"
date.pl -r /etc/passwd          # display mtime of /etc/passwd
date.pl -r /etc/passwd -d "12:00:00" # date of /etc/passwd, time of noon
EOT
                exit(1);
        }
        else {       die("unknown argument $arg, try --help");   }
}

# Load hashes full of day and month names

#loadhash(\%month, `locale mon`, `locale abmon`);
loadhash(\%month, "January;February;March;April;May;June;July;August;September;October;November;December",
	"Jan;Feb;Mar;Apr;May;Jun;Jul;Aug;Sep;Oct;Nov;Dec");
#loadhash(\%days, `locale day`, `locale abday`);
loadhash(\%days, "Sunday;Monday;Tuesday;Wednesday;Thursday;Friday;Saturday",
	"Sun;Mon;Tues;Wed;Thurs;Fri;Sat");

@lt=localtime($ref);

# Lowercase input so 'tues', etc can be reliably found in tables
$input=lc($input); 
# Separate strings and numbers into their own tokens, like "9am" => "9 am"
# : still belongs with numbers for HH:MM:SS etc.
$input =~ s/([0-9:])([a-z])/$1 $2/g;
$input =~ s/([a-z])([0-9:])/$1 $2/g;
# Split +/- into their own tokens
$input =~ s/([+-])/ $1 /g;

# Split input on whitespace and commas and jam back into ARGV
unshift(@ARGV, split(/[ \r\n\t,]+/, $input));

while(defined($arg=shift))
{
        if(length($arg) == 0){ next; } # Empty string?  Ignore

	# Handle these in offset section
	if(($arg eq "+")||($arg eq "plus")||($arg eq "-")||($arg eq "minus"))
	{	unshift(@ARGV, $arg);	last;	}

        ################## DATE FORMAT DETECTION ########################

	if(exists($month{$arg})) # Dates like "Jan" "17"
	{
		set(MON, $month{$arg});
		if(($#ARGV >= 0) && ($ARGV[0] =~ /^[0-9]+$/))
		{	set(DAY, $ARGV[0] + 0);	shift;	}
		next;
	}

	if(exists($days{$arg}))	# mon/monday/etc
        {
		set(WDAY, $days{$arg} );

		# If it's followed by a numeral, i.e. Monday 7,
		# the numeral is the day of the month
		if(($#ARGV >= 0) && ($ARGV[0] =~ /^[0-9]+$/))
		{ set(DAY, $ARGV[0] + 0); shift; }

		next;
	}

	# a bare 4-digit number beginning with 19 or 20 is probably a year
	if($arg =~ /^(19[0-9][0-9])|^(2[0-9][0-9][0-9])$/)
	{	set(YEAR, $arg - 1900);	next;	}

        # @1234 means seconds in epoch time
        if($arg =~ /^@([0-9]+)$/)      {
		@lt=localtime($1+0);
		# Date has been replaced, prev changes are now irrelevant
		for($n=0; $n<8; $n++) { $changed[$n]=undef; }
		next;
	}

        # Checks for YYYYMMDD or YYYY/MM/DD time
        if(($arg =~ /^([0-9]{4})([\/-])([0-9]{1,2})\2([0-9]{1,2})$/) ||
		($arg =~ /^([0-9]{4})()([0-9]{2})([0-9]{2})$/))
        {
		set(YEAR, $1-1900); set(MON, $3-1); set(DAY, $4+0);

		# Set time variables which haven't been set already
		if(!defined($changed[HOUR]))
		{ set(SEC,0); set(MIN,0); set(HOUR,0); }

                next;
        }

        # HH:MM:SS times.  Sub-second times are allowed but ignored
        if($arg =~ /([0-2]?[0-9]):([0-5][0-9])(:([0-5][0-9])(.[0-9]+)?)?$/)
        {
		if(defined($4)) { set(SEC, $4+0); }
		else		{ set(SEC, 0); }

		set(MIN, $2+0);	set(HOUR, $1+0);

		# Handle time with PM in it
		if($#ARGV < 0) { }
		elsif($ARGV[0] eq "pm")  { set(HOUR, pm($lt[HOUR])); shift; }
		elsif($ARGV[0] eq "am")  { set(HOUR, am($lt[HOUR])); shift; }
                next;
        }

        # Times like 9 AM
        if(($arg =~ /^([0-9]+)$/) && ($#ARGV>=0) && ($ARGV[0] =~ /^(am|pm)$/)) {
		$arg=$arg + 0;

		set(SEC, 0); set(MIN,0); set(HOUR, $arg);
		if($ARGV[0] eq "am") { set(HOUR, am($lt[HOUR])); }
		else                 { set(HOUR, pm($lt[HOUR])); }
		shift;
		next;
	}

	# Redundant, but whatever
        if($arg =~ /^now$/)  {
		@lt=localtime(time);
		# Date has been replaced, prev changes are now irrelevant
		for($n=0; $n<8; $n++) { $changed[$n]=undef; }
		next
	}

	# last second/minute/hour/week/year
	if($arg =~ /^(last)|(next)$/)
	{
		if(defined($1)) { $sign=-1; } else { $sign=1; }

		if($#ARGV < 0)
		{
			if(!$quiet)
			{	print STDERR "next what, exactly?\n"	}

			next;
		}

		if(defined($mult{$ARGV[0]}))
		{
			@lt=localtime(time);
			# Date has been replaced, prev changes now irrelevant
			for($n=0; $n<8; $n++) { $changed[$n]=undef; }
			$offset *= $mult{$ARGV[0]};
		}
		# Adding months can't be handled in offset sadly
		elsif(($ARGV[0] eq "month") || ($ARGV[0] eq "months"))
		{	add_month($sign);	}
		elsif(!$quiet)
		{
			print STDERR $ARGV[0]." not a valid option for next\n";
		}

		shift;
		next;
	}

        if(! $quiet) { print STDERR "Unknown argument $arg\n"; }
}

# If there are any arguments left, we found a +/- and need to process
# that time offset.
while(defined($arg=shift))
{
        if(length($arg) == 0){ next; } # Empty string?  Ignore

	if(($arg eq "plus") || ($arg eq "+"))	{ $sign=1; next; }
	if(($arg eq "minus") ||($arg eq "-"))	{ $sign=-1; next; }

	# A number followed by a type, "9" "years"
	if(($arg =~ /^[0-9]+$/) && ($#ARGV >= 0))
	{
		my $arg2=shift;

		if((! $sign)&&(!$quiet))
		{
			print STDERR "Warning, no sign for numeric value\n"
		}

		# second/minute/hour/day/week/year are just multiplication
		if(defined($mult{$arg2}))
		{ $offset += $mult{$arg2} * $arg * $sign; next; }
		# No exact number of seconds per month, just count
		elsif(($arg2 eq "month")||($arg2 eq "months"))
		{ add_month($sign * $arg); next; }

		# Leave for error handler below to find
		$arg=$arg2;
	}

	# If we get here, something went wrong.
	if(!$quiet) {
		print STDERR "Unknown syntax ".$ARGV[0]."\n";
	}
}

my $nref=mktime(@lt); # Convert the altered @lt values back into epoch time

# Sanity checking.  If localtime(mktime(@lt)) produces different values
# from what was in @lt, we must have given it a nonsensical value which
# mktime corrected.
my @san=localtime($nref);

# Titles for localtime() array elements
my @title=("Seconds","Minutes","Hours","Day","Month","Year","Weekday");

for($n=0; $n<=6; $n++)
{
	if(($quiet == 0) && defined($changed[$n]) && ($changed[$n] != $san[$n]))
	{
		printf STDERR "%s changed, inconsistent input?", $title[$n];
		printf STDERR "\t%s in %s out\n", $changed[$n], $san[$n];
	}
}

# Print the calculated time plus offset
print strftime($cmdstr."\n", localtime($nref + ($offset)));
exit(0);

#########################################################################
################################ SUBROUTINES ############################
#########################################################################

# Adds or subtracts a number of months to the time in @lt,
# accounting for year wraparound when the number goes above 11 or below 0
sub add_month {
	$lt[MON] += shift;
	while($lt[MON] >= 12) { $lt[YEAR]++; $lt[MON] -= 12; }
	while($lt[MON] < 0) { $lt[MON] += 12; $lt[YEAR] --; }

	set(MON, $lt[MON]);
	set(YEAR, $lt[YEAR]);
}

# Alter a value in @lt, and mark that index as 'changed' by altering
# the value in @changed too
sub set { my ($i,$v)=(shift,shift); $lt[$i]=$changed[$i]=$v; }

# Takes a numeric AM hour, returns a number in 24-hour time
sub am { if($_[0] == 12) { return($_[0] - 12); } return($_[0]); }
# Takes a numeric PM hour, returns an hour in 24-hour time
sub pm { if($_[0] >= 1) { return($_[0] + 12); } return($_[0]); }

# loadhash(\%hash, "A;B", "a;b")
# sets $hash{A}=0, $hash{B}=1, $hash{a}=0, $hash{b}=1
sub loadhash {
        my ($h,$n)=(shift,0);
	foreach(@_)	{
		$n=0; foreach(split('[;\n]', lc($_))) { ${$h}{$_}=$n++; }
	}
}


Last edited by Corona688; 06-06-2016 at 12:21 PM.. Reason: Tenth revision, fixed typo, add_months/add_month
The Following 3 Users Say Thank You to Corona688 For This Useful Post:
Neo (10-25-2013), RavinderSingh13 (09-16-2016), Scrutinizer (01-20-2014)
Sponsored Links
    #2  
Old Unix and Linux 10-25-2013   -   Original Discussion by Corona688
targzeta's Unix or Linux Image
targzeta targzeta is offline
Registered User
 
Join Date: Oct 2013
Last Activity: 3 December 2013, 1:49 PM EST
Location: Pisa, Italy
Posts: 27
Thanks: 1
Thanked 5 Times in 5 Posts
Ok, I'm using Linux Slackware64 but...
Code:
perl date.pl 
Can't locate Switch.pm in @INC (you may need to install the Switch module) (@INC contains: /usr/local/lib64/perl5
 /usr/local/share/perl5 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5 .) at date.pl line 3.
BEGIN failed--compilation aborted at date.pl line 3.

it seems that Switch it's no so standard Linux.

Is it a bug?
Code:
# 1)
$> date --date="2013/10/20 - 203 days" '+%Y-%m-%d %H-%M-%S'
2013-03-31 00-00-00

$> perl date.pl -d '2013/10/20 - 203 days'
2013-03-30 23:00:00

# 2)
$> date --date="2013/10/25 + 3 days" '+%Y-%m-%d %H-%M-%S'
2013-10-28 00-00-00

$> perl date.pl -d '2013/10/25 + 3 days'
2013-10-27 23:00:00

# 3)
$> perl date.pl -d 'now + 3 days'
Unknown argument now

$> perl date.pl -d 'today + 3 days'
Unknown argument today

I think it's very hard what you're trying to do.

Emanuele
The Following User Says Thank You to targzeta For This Useful Post:
Corona688 (10-25-2013)
Sponsored Links
    #3  
Old Unix and Linux 10-25-2013   -   Original Discussion by Corona688
Corona688's Unix or Linux Image
Corona688 Corona688 is offline Forum Staff  
Mead Rotor
 
Join Date: Aug 2005
Last Activity: 13 December 2017, 10:16 AM EST
Location: Saskatchewan
Posts: 22,546
Thanks: 1,159
Thanked 4,286 Times in 3,955 Posts
Bug noted, thank you a lot, I had --date "something" when I should have done --date="something".

Thanks for reminding me about the +syntax feature, which I'd planned but forgotten.

Date math is not hard here, I am letting mktime handle absolutely everything tricky. I do not need to know when the next leap year is, I subtract 1 from the 'year' value and let mktime decide what that is.

Yes yes I know that Perl has about 37 different date modules I could be using. But if I'm going to tell someone to install 'Perl::MyFavoriteDateModule' I might as well just tell them to install GNU date. The whole point is to not do that, (and to show elegant Perl code is possible without including the kitchen sink).

Some of those tests are just weird though. I have no idea how you got 23 hours from subtracting days, it certainly doesn't happen here. I may have done something odd with a last-minute fix when I posted. [edit] Now I know. It happened because of the --date vs --date= problem. Perl does strange things when you do arithmetic on strings.

Anyway, I'll incorporate your suggestions and repost. Thanks again. [edit] Version 2 is now in the OP.

Last edited by Corona688; 10-25-2013 at 06:57 PM..
    #4  
Old Unix and Linux 10-25-2013   -   Original Discussion by Corona688
Corona688's Unix or Linux Image
Corona688 Corona688 is offline Forum Staff  
Mead Rotor
 
Join Date: Aug 2005
Last Activity: 13 December 2017, 10:16 AM EST
Location: Saskatchewan
Posts: 22,546
Thanks: 1,159
Thanked 4,286 Times in 3,955 Posts
Updated. switch() removed, known bugs fixed, +formatting added.
Sponsored Links
    #5  
Old Unix and Linux 10-25-2013   -   Original Discussion by Corona688
targzeta's Unix or Linux Image
targzeta targzeta is offline
Registered User
 
Join Date: Oct 2013
Last Activity: 3 December 2013, 1:49 PM EST
Location: Pisa, Italy
Posts: 27
Thanks: 1
Thanked 5 Times in 5 Posts
I think the problem is with daylight saving time. But, see this:
Code:
# 1) correct
$> perl date.pl -d 'now + 3 days'
2013-10-28 23:24:14
$> date -d 'now + 3 days'
Mon Oct 28 23:24:20 CET 2013

#2) error:
$> perl date.pl -d '2013/10/25 + 3 days'
2013-10-27 23:00:00
$> date -d '2013/10/25 + 3 days'
Mon Oct 28 00:00:00 CET 2013

I hope this can help you,
Emanuele
The Following User Says Thank You to targzeta For This Useful Post:
Corona688 (10-28-2013)
Sponsored Links
    #6  
Old Unix and Linux 10-28-2013   -   Original Discussion by Corona688
Corona688's Unix or Linux Image
Corona688 Corona688 is offline Forum Staff  
Mead Rotor
 
Join Date: Aug 2005
Last Activity: 13 December 2017, 10:16 AM EST
Location: Saskatchewan
Posts: 22,546
Thanks: 1,159
Thanked 4,286 Times in 3,955 Posts
I get no such errors here, even when fiddling with the TZ variable (which perl appears to support). What version of perl do you use?

The real error was that the string 'now', which caused no errors, wasn't supported and should have been flagged.

Error detection has been made more robust as a result and support for 'now' added:


Code:
#!/usr/bin/perl

use POSIX;

my $cmdstr="%Y-%m-%d %H:%M:%S";
my ($input, $arg, $sign)=(undef, undef, 0);
my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst)=localtime();

# Commandline parsing stuff
while(defined($arg=shift)) {
        if($arg =~ /^--date=/)  {       $input=substr($arg, 7);         }
        elsif($arg =~ /^-d$/)   {       $input=shift;                   }
        elsif($arg =~/^\+/)     {       $cmdstr=substr($arg,1);         }
        else                    {       print STDERR "unknown $arg\n";  }
}

# Put the date string back into argv, split on spaces
unshift(@ARGV, split(/[ \t]+/, $input));

while(defined($arg=shift))
{
        # Need to split +1 into +1
        if($arg =~ /^[+]/) {    $sign=1;        $arg=substr($arg,1);    }
        elsif($arg =~ /^-/) {   $sign=-1;       $arg=substr($arg,1);    }

        ################## DATE FORMAT DETECTION ########################

        # @1234 means seconds in epoch time
        if($arg =~ /^@[0-9]+$/)
        {
                ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst)=localtime($1+0);
                next;
        }

        # Checks for YYYYMMDD or YYYY/MM/DD time
        # TODO:  Check for YYMMDD dates
        # TODO:  Check for YYYYDDMM dates (ugh)
        if($arg =~ /^([0-9]{4})(\/?)([0-9]{2})\2([0-9]{2})/)
        {
                ($year,$mon,$mday)=($1-1900,$3-1,$4+0);
                ($sec,$min,$hour)=(0,0,0);
                next;
        }

        # HH:MM:SS times
        if($arg =~ /([0-2][0-9]):([0-5][0-9]):([0-5][0-9])(.[0-9]+)?$/)
        {
                ($sec,$min,$hour)=($3+0, $2+0, $1+0);
                next;
        }

        # As last resort, assume its a pure number.
        if($arg =~ /^([0-9]+)$/) {
                if($sign == 0)
                {
                        print STDERR "offset without unit";
                        exit(1);
                }

                $offset=$1+0;
                next;
        }

        if($arg =~ /^seconds?$/)        {       }
        elsif ($arg =~ /^years?$/) {
                                        $year += ($offset*$sign);
                                        $sign=0;
                                        $offset=0;
                                }
        elsif($arg =~ /^minutes?$/)     {       $offset *= 60;          }
        elsif($arg =~ /^hours?/)        {       $offset *= 60*60;       }
        elsif($arg =~ /^days?/)         {       $offset *= 60*60*24;    }
        elsif($arg =~ /^weeks?/)        {       $offset *= 60*60*24*7;  }
        elsif($arg =~ /^months?$/)      {

                                        $mon += ($offset*$sign);

                                        while($mon > 12)
                                        {
                                                $mon-=12;
                                                $year++;
                                        }

                                        while($mon < 0)
                                        {
                                                $mon+=12;
                                                $year--;
                                        }

                                        $sign=0;
                                        $offset=0;
                                }
        elsif($arg =~ /^now$/)  {
                ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst)=localtime();
        }
        elsif(length($arg) == 0){       } # Empty string?  Ignore
        else                    {
                                        print STDERR "Unknown argument $arg\n";
                                        exit(1);
        }
}

# Convert the altered year, month, etc back into epoch time.
my $ref=mktime($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst);
# Add the seconds offset calculated above.
$ref += ($sign * $offset);
# Convert back into list.
($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst)=localtime($ref);

print strftime($cmdstr."\n",
        $sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst);


Last edited by Corona688; 10-28-2013 at 01:16 PM..
Sponsored Links
    #7  
Old Unix and Linux 01-15-2014   -   Original Discussion by Corona688
Corona688's Unix or Linux Image
Corona688 Corona688 is offline Forum Staff  
Mead Rotor
 
Join Date: Aug 2005
Last Activity: 13 December 2017, 10:16 AM EST
Location: Saskatchewan
Posts: 22,546
Thanks: 1,159
Thanked 4,286 Times in 3,955 Posts
An updated version which supports --reference/-r:


Code:
#!/usr/bin/perl

use POSIX;

my $cmdstr="%Y-%m-%d %H:%M:%S";
my ($input, $arg, $sign, $file)=(undef, undef, 0, undef);
my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst)=localtime();

# Commandline parsing stuff
while(defined($arg=shift)) {
        if($arg =~ /^--date=/)  {       $input=substr($arg, 7);         }
        elsif($arg =~ /^-d$/)   {       $input=shift;                   }
        elsif($arg =~ /^-r$/)   {       $file=shift;                    }
        elsif($arg =~ /^--reference=/) {$file=substr($arg, 12);         }
        elsif($arg =~/^\+/)     {       $cmdstr=substr($arg,1);         }
        else                    {       die("unknown argument $arg");   }
}

if(defined($file)) {
        my ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,
               $atime,$mtime,$ctime,$blksize,$blocks)
               = stat($file);

        defined($dev) || die("No such file $file");


        ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst)
                = localtime($mtime);
}

# Put the date string back into argv, split on spaces
unshift(@ARGV, split(/[ \t]+/, $input));

while(defined($arg=shift))
{
        # Need to split +1 into +1
        if($arg =~ /^[+]/) {    $sign=1;        $arg=substr($arg,1);    }
        elsif($arg =~ /^-/) {   $sign=-1;       $arg=substr($arg,1);    }

        ################## DATE FORMAT DETECTION ########################

        # @1234 means seconds in epoch time
        if($arg =~ /^@[0-9]+$/)
        {
                ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst)=localtime($1+0);
                next;
        }

        # Checks for YYYYMMDD or YYYY/MM/DD time
        # TODO:  Check for YYMMDD dates
        # TODO:  Check for YYYYDDMM dates (ugh)
        if($arg =~ /^([0-9]{4})(\/?)([0-9]{2})\2([0-9]{2})/)
        {
                ($year,$mon,$mday)=($1-1900,$3-1,$4+0);
                ($sec,$min,$hour)=(0,0,0);
                next;
        }

        # HH:MM:SS times
        if($arg =~ /([0-2][0-9]):([0-5][0-9]):([0-5][0-9])(.[0-9]+)?$/)
        {
                ($sec,$min,$hour)=($3+0, $2+0, $1+0);
                next;
        }

        # As last resort, assume its a pure number.
        if($arg =~ /^([0-9]+)$/) {
                if($sign == 0)
                {
                        print STDERR "offset without unit";
                        exit(1);
                }

                $offset=$1+0;
                next;
        }

        if($arg =~ /^seconds?$/)        {       }
        elsif ($arg =~ /^years?$/) {
                                        $year += ($offset*$sign);
                                        $sign=0;
                                        $offset=0;
                                }
        elsif($arg =~ /^minutes?$/)     {       $offset *= 60;          }
        elsif($arg =~ /^hours?/)        {       $offset *= 60*60;       }
        elsif($arg =~ /^days?/)         {       $offset *= 60*60*24;    }
        elsif($arg =~ /^weeks?/)        {       $offset *= 60*60*24*7;  }
        elsif($arg =~ /^months?$/)      {

                                        $mon += ($offset*$sign);

                                        while($mon > 12)
                                        {
                                                $mon-=12;
                                                $year++;
                                        }

                                        while($mon < 0)
                                        {
                                                $mon+=12;
                                                $year--;
                                        }

                                        $sign=0;
                                        $offset=0;
                                }
        elsif($arg =~ /^now$/)  {
                ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst)=localtime();
        }
        elsif(length($arg) == 0){       } # Empty string?  Ignore
        else                    {
                                        print STDERR "Unknown argument $arg\n";
                                        exit(1);
        }
}

# Convert the altered year, month, etc back into epoch time.
my $ref=mktime($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst);
# Add the seconds offset calculated above.
$ref += ($sign * $offset);
# Convert back into list.
($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst)=localtime($ref);

print strftime($cmdstr."\n",
        $sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst);

The Following 2 Users Say Thank You to Corona688 For This Useful Post:
Scott (01-16-2014), Yoda (01-15-2014)
Sponsored Links
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Linux More UNIX and Linux Forum Topics You Might Find Helpful
Thread Thread Starter Forum Replies Last Post
Purpose of - (hypen) in script or command line gwgreen1 UNIX for Dummies Questions & Answers 1 07-25-2011 03:24 AM
whats the purpose of the following script? vrn UNIX for Dummies Questions & Answers 1 03-20-2006 09:15 PM
Looking for a general purpose System Monitor darthur UNIX for Dummies Questions & Answers 5 04-09-2002 04:12 PM



All times are GMT -4. The time now is 04:09 AM.