Re: Command-line-interface (CLI) calculator to work out the difference between 2 dates
On 2008-08-26 11:50, Ron Johnson wrote: On 08/25/08 20:34, s. keeling wrote: Ron Johnson [EMAIL PROTECTED]: On 08/24/08 11:32, Rick Pasotto wrote: Why pipe it to bc? Keep it in the shell: $ echo $[$[$(date -d 20090824 +%s) - $(date -d 20080724 +%s)] / 86400] 396 [snip] One stylistic reason for piping to bc is that some people think that bash's $[] syntax gets too hard to read if you nest it too much. I've been running *nix on my home boxes since '93, and I've never even seen that syntax. That's a bashism, I hope? Yes. And a relatively modern one at that. Somewhere in the 3.x series. Maybe not to modern. Just looking at man bash on lenny: Arithmetic Expansion Arithmetic expansion allows the evaluation of an arithmetic expression and the substitution of the result. The format for arithmetic expansion is: $((expression)) The old format $[expression] is deprecated and will be removed in upcoming versions of bash. -- *old format* Johannes signature.asc Description: OpenPGP digital signature
Re: Command-line-interface (CLI) calculator to work out the difference between 2 dates
Arithmetic Expansion Arithmetic expansion allows the evaluation of an arithmetic expression and the substitution of the result. The format for arithmetic expansion is: $((expression)) The old format $[expression] is deprecated and will be removed in upcoming versions of bash. Thanks for bringing the syntax for the evaluation of arithmetic expressions in bash to my attention echo '' $[ (16/2 + 6) * 3 ] Previously, I had totally missed it :-) -- Stanley C. Kitching Human Being Phoenix, Arizona -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Command-line-interface (CLI) calculator to work out the difference between 2 dates
On 08/25/08 20:34, s. keeling wrote: Ron Johnson [EMAIL PROTECTED]: On 08/24/08 11:32, Rick Pasotto wrote: Why pipe it to bc? Keep it in the shell: $ echo $[$[$(date -d 20090824 +%s) - $(date -d 20080724 +%s)] / 86400] 396 [snip] One stylistic reason for piping to bc is that some people think that bash's $[] syntax gets too hard to read if you nest it too much. I've been running *nix on my home boxes since '93, and I've never even seen that syntax. That's a bashism, I hope? Yes. And a relatively modern one at that. Somewhere in the 3.x series. I do own, and have studied, O'Really's Learning the bash shell. -- Ron Johnson, Jr. Jefferson LA USA Do not bite at the bait of pleasure till you know there is no hook beneath it. -- Thomas Jefferson -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Command-line-interface (CLI) calculator to work out the difference between 2 dates
On Tue, Aug 26, 2008 at 04:50:16AM -0500, Ron Johnson wrote: On 08/25/08 20:34, s. keeling wrote: I've been running *nix on my home boxes since '93, and I've never even seen that syntax. That's a bashism, I hope? Yes. And a relatively modern one at that. Somewhere in the 3.x series. I see it also works in zsh. Regards Johann -- Johann Spies Telefoon: 021-808 4036 Informasietegnologie, Universiteit van Stellenbosch Seeing then that all these things shall be dissolved, what manner of persons ought ye to be in all holy conversation and godliness, Looking for and hasting unto the coming of the day of God, wherein the heavens being on fire shall be dissolved, and the elements shall melt with fervent heat? II Peter 3:11,12 -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Command-line-interface (CLI) calculator to work out the difference between 2 dates
Ron Johnson [EMAIL PROTECTED]: On 08/24/08 11:32, Rick Pasotto wrote: Why pipe it to bc? Keep it in the shell: $ echo $[$[$(date -d 20090824 +%s) - $(date -d 20080724 +%s)] / 86400] 396 [snip] One stylistic reason for piping to bc is that some people think that bash's $[] syntax gets too hard to read if you nest it too much. I've been running *nix on my home boxes since '93, and I've never even seen that syntax. That's a bashism, I hope? I do own, and have studied, O'Really's Learning the bash shell. -- Any technology distinguishable from magic is insufficiently advanced. (*)http://blinkynet.net/comp/uip5.html Linux Counter #80292 - -http://www.faqs.org/rfcs/rfc1855.htmlPlease, don't Cc: me. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Command-line-interface (CLI) calculator to work out the difference between 2 dates
On Sunday 24 August 2008 18.07.59 j t wrote: Hi all. Does anyone have any suggestions for a command-line-interface (CLI) calculator that can work out the difference between 2 (gregorian) dates (i.e. that is calendar aware). My favourite cli calculator (bc) doesn't seem to have any knowledge of the gregorian calendar. Just to make it clear, I'd like to be able to type in: 20080824-20080724 and it would work out the answer as 31 While I'm sure someone else will provide a much better way, I've used something like $ echo $(date -d 20080824 +%j) - $(date -d 20080724 +%j) | bc 31 ..in the past. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Command-line-interface (CLI) calculator to work out the difference between 2 dates
On 08/24/08 10:07, j t wrote: Hi all. Does anyone have any suggestions for a command-line-interface (CLI) calculator that can work out the difference between 2 (gregorian) dates (i.e. that is calendar aware). My favourite cli calculator (bc) doesn't seem to have any knowledge of the gregorian calendar. Just to make it clear, I'd like to be able to type in: 20080824-20080724 and it would work out the answer as 31 (I'm happy to use any date format for input - I've only used ISO8601 as an example) I think I'd write a simple Python/Perl script: convert date1 and date2 to seconds past epoch, subtract, and divide by 86400. -- Ron Johnson, Jr. Jefferson LA USA Do not bite at the bait of pleasure till you know there is no hook beneath it. -- Thomas Jefferson -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Command-line-interface (CLI) calculator to work out the difference between 2 dates
j t wrote: Hi all. Does anyone have any suggestions for a command-line-interface (CLI) calculator that can work out the difference between 2 (gregorian) dates (i.e. that is calendar aware). My favourite cli calculator (bc) doesn't seem to have any knowledge of the gregorian calendar. Just to make it clear, I'd like to be able to type in: 20080824-20080724 and it would work out the answer as 31 (I'm happy to use any date format for input - I've only used ISO8601 as an example) I Googled date arithmetic, and found this, http://www.walkernews.net/2007/06/03/date-arithmetic-in-linux-shell-scripts/ Can you adapt from that? cheers, gary -- Anyone can make a usable web site. It takes a graphic designer to make it slow, confusing and painful to use. begin:vcard fn:Gary Turner n:Turner;Gary org:Gary Turner, Web Developer adr:;;USA email;internet:[EMAIL PROTECTED] title:Czar x-mozilla-html:FALSE url:http://gtwebdev.com/ version:2.1 end:vcard
Re: Command-line-interface (CLI) calculator to work out the difference between 2 dates
On 08/24/08 10:54, Edward J. Shornock wrote: [snip] While I'm sure someone else will provide a much better way, I've used something like $ echo $(date -d 20080824 +%j) - $(date -d 20080724 +%j) | bc 31 That a good idea. I never knew date(1) could do that. The problem, though, is that it doesn't span years. $ echo $(date -d 20090824 +%j) - $(date -d 20080724 +%j) | bc 30 Use delta from epoch, instead. $ echo $[$(date -d 20090824 +%s) - $(date -d 20080724 +%s)]/86400|bc 396 -- Ron Johnson, Jr. Jefferson LA USA Do not bite at the bait of pleasure till you know there is no hook beneath it. -- Thomas Jefferson -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Command-line-interface (CLI) calculator to work out the difference between 2 dates
On Sun, Aug 24, 2008 at 11:25:31AM -0500, Ron Johnson wrote: On 08/24/08 10:54, Edward J. Shornock wrote: [snip] While I'm sure someone else will provide a much better way, I've used something like $ echo $(date -d 20080824 +%j) - $(date -d 20080724 +%j) | bc 31 That a good idea. I never knew date(1) could do that. The problem, though, is that it doesn't span years. $ echo $(date -d 20090824 +%j) - $(date -d 20080724 +%j) | bc 30 Use delta from epoch, instead. $ echo $[$(date -d 20090824 +%s) - $(date -d 20080724 +%s)]/86400|bc 396 Why pipe it to bc? Keep it in the shell: $ echo $[$[$(date -d 20090824 +%s) - $(date -d 20080724 +%s)] / 86400] 396 -- Curiosity is the very basis of education and if you tell me that curiosity killed the cat, I say only the cat died nobly. -- Arnold Edinborough Rick Pasotto[EMAIL PROTECTED]http://www.niof.net -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Command-line-interface (CLI) calculator to work out the difference between 2 dates
On 08/24/08 11:32, Rick Pasotto wrote: On Sun, Aug 24, 2008 at 11:25:31AM -0500, Ron Johnson wrote: On 08/24/08 10:54, Edward J. Shornock wrote: [snip] While I'm sure someone else will provide a much better way, I've used something like $ echo $(date -d 20080824 +%j) - $(date -d 20080724 +%j) | bc 31 That a good idea. I never knew date(1) could do that. The problem, though, is that it doesn't span years. $ echo $(date -d 20090824 +%j) - $(date -d 20080724 +%j) | bc 30 Use delta from epoch, instead. $ echo $[$(date -d 20090824 +%s) - $(date -d 20080724 +%s)]/86400|bc 396 Why pipe it to bc? Keep it in the shell: $ echo $[$[$(date -d 20090824 +%s) - $(date -d 20080724 +%s)] / 86400] 396 I was thinking that integer division might result in the occasional rounding error. But now that I think about it, that wouldn't matter, since bc does integer math unless you pass it -l. One stylistic reason for piping to bc is that some people think that bash's $[] syntax gets too hard to read if you nest it too much. -- Ron Johnson, Jr. Jefferson LA USA Do not bite at the bait of pleasure till you know there is no hook beneath it. -- Thomas Jefferson -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Command-line-interface (CLI) calculator to work out the difference between 2 dates
On Sun, 2008-08-24 at 11:25 -0500, Ron Johnson wrote: On 08/24/08 10:54, Edward J. Shornock wrote: [snip] While I'm sure someone else will provide a much better way, I've used something like $ echo $(date -d 20080824 +%j) - $(date -d 20080724 +%j) | bc 31 That a good idea. I never knew date(1) could do that. The problem, though, is that it doesn't span years. $ echo $(date -d 20090824 +%j) - $(date -d 20080724 +%j) | bc 30 Use delta from epoch, instead. $ echo $[$(date -d 20090824 +%s) - $(date -d 20080724 +%s)]/86400|bc 396 Why the /86400? I follow all of the above but that operation and number. -- Ron Johnson, Jr. Jefferson LA USA Do not bite at the bait of pleasure till you know there is no hook beneath it. -- Thomas Jefferson -- Damon L. Chesser [EMAIL PROTECTED] -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Command-line-interface (CLI) calculator to work out the difference between 2 dates
On 24 Ago, 17:10, j t [EMAIL PROTECTED] wrote: [snip] (I'm happy to use any date format for input - I've only used ISO8601 as an example) Maybe something like that: #!/usr/bin/python from time import mktime, strptime from sys import argv class DummyDate: def __init__(self, strdate, format): self.ticks = mktime(strptime(strdate, format)); def __sub__(self, obj): return int(self.ticks - obj.ticks) / 86400; (prg, a, b, fmt) = argv print DummyDate(a, fmt) - DummyDate(b, fmt) ## end Or using a sh script with date(1) J :-) s. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Command-line-interface (CLI) calculator to work out the difference between 2 dates
On 08/24/08 12:41, Damon L. Chesser wrote: On Sun, 2008-08-24 at 11:25 -0500, Ron Johnson wrote: On 08/24/08 10:54, Edward J. Shornock wrote: [snip] While I'm sure someone else will provide a much better way, I've used something like $ echo $(date -d 20080824 +%j) - $(date -d 20080724 +%j) | bc 31 That a good idea. I never knew date(1) could do that. The problem, though, is that it doesn't span years. $ echo $(date -d 20090824 +%j) - $(date -d 20080724 +%j) | bc 30 Use delta from epoch, instead. $ echo $[$(date -d 20090824 +%s) - $(date -d 20080724 +%s)]/86400|bc 396 Why the /86400? I follow all of the above but that operation and number. 60 seconds * 60 minutes * 24 hours = 86400 seconds --- --- - --- minute hour day day -- Ron Johnson, Jr. Jefferson LA USA Do not bite at the bait of pleasure till you know there is no hook beneath it. -- Thomas Jefferson -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Command-line-interface (CLI) calculator to work out the difference between 2 dates
On 2008-08-24 11:13:43 -0500, Ron Johnson wrote: I think I'd write a simple Python/Perl script: convert date1 and date2 to seconds past epoch, subtract, and divide by 86400. In Perl, you can also use the Date::Manip module: 4. The amount of time between two dates. $date1 = ParseDate($string1); $date2 = ParseDate($string2); $delta = DateCalc($date1,$date2,\$err); = 0:0:WK:DD:HH:MM:SS the weeks, days, hours, minutes, and seconds between the two $delta = DateCalc($date1,$date2,\$err,1); = YY:MM:WK:DD:HH:MM:SS the years, months, etc. between the two -- Vincent Lefèvre [EMAIL PROTECTED] - Web: http://www.vinc17.org/ 100% accessible validated (X)HTML - Blog: http://www.vinc17.org/blog/ Work: CR INRIA - computer arithmetic / Arenaire project (LIP, ENS-Lyon) -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Command-line-interface (CLI) calculator to work out the difference between 2 dates
On 2008-08-24 12:25:00 -0500, Ron Johnson wrote: I was thinking that integer division might result in the occasional rounding error. This is the contrary: AFAIK, you really want an integer division. So, integer arithmetic is OK. But a floating-point division can be a problem since when the floating-point result is displayed, it may be rounded to the next integer if at most 4 digits are displayed after the decimal point, the worst case being: $ echo 86399/86400 | bc -l .8842592592592592 For instance, under a shell that supports FP arithmetic (e.g. zsh): $ printf %.4f\n $((86399./86400)) 1. Now, assuming you want to use floating-point arithmetic, before displaying the result, you may want to take the floor of the result: vin% zmodload zsh/mathfunc vin% printf %.0f\n $((floor(86399./86400))) 0 vin% printf %.0f\n $((floor(86400./86400))) 1 And I proved that under some conditions (which are satisfied here), one gets the same result as the integer division: http://www.vinc17.org/research/papers/rr_intdiv.pdf -- Vincent Lefèvre [EMAIL PROTECTED] - Web: http://www.vinc17.org/ 100% accessible validated (X)HTML - Blog: http://www.vinc17.org/blog/ Work: CR INRIA - computer arithmetic / Arenaire project (LIP, ENS-Lyon) -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
