Re: rdate(8) manpage clarification
On Thursday, April 12, 2007 at 23:21:28 -0500, Matthew R. Dempsky wrote: On Thu, Apr 12, 2007 at 10:34:25PM +0200, Maurice Janssen wrote: The manpage for rdate(8) uses the -c option in the examples at the bottom (leap second correction), but the given host (ptbtime1.ptb.de) doesn't need this. SNTP gives time in UTC, but some sysadmins would prefer to synchronize their system time to TAI rather than UTC (e.g., so time values returned by gettimeofday(2) progresses normally during leap seconds). The -c argument for rdate is intended for their use. Yes, that's clear. Basic rule of thumb is use -c if and only if you're using a timezone file under /usr/share/zoneinfo/right/ (i.e., one that includes leap second info). Otherwise your clock will most likely be off by 23 seconds. I missed the word 'right' in the timezone in the example, thanks for pointing it out. Maurice
Re: rdate(8) manpage clarification
On Friday, April 13, 2007 at 01:25:58 +0059, Jason McIntyre wrote: On Thu, Apr 12, 2007 at 10:34:25PM +0200, Maurice Janssen wrote: Hi, The manpage for rdate(8) uses the -c option in the examples at the bottom (leap second correction), but the given host (ptbtime1.ptb.de) doesn't need this. In fact, I've never come across a time server that needed -c, but I suppose there are some servers out there that need it. Anyway, I think it's better to skip the -c option in the examples. Maurice why? if you need -c, you have it. if you don't, it won;t do any harm to specify it. as i understand it, -nc is a fair combination. At first, I thought that -c is needed to correct for replies from broken servers (hence my remark that ptbtime1.ptb.de doesn't need it). As Matthew pointed out, it is needed when using a zone under /usr/share/zoneinfo/right/ and using TAI instead of UTC for the system clock. Perhaps this can be added to the manpage. Something like: -c Correct leap seconds. Only needed when the system clock is set to TAI instead of the default UTC to avoid steps during leap second insertions. In this case, a timezone under /usr/share/zoneinfo/right/ should be used to display the correct local time. I'm not sure about the last sentence. It has nothing to do with rdate, but makes the whole thing clearer IMHO. Maurice
rdate(8) manpage clarification
Hi, The manpage for rdate(8) uses the -c option in the examples at the bottom (leap second correction), but the given host (ptbtime1.ptb.de) doesn't need this. In fact, I've never come across a time server that needed -c, but I suppose there are some servers out there that need it. Anyway, I think it's better to skip the -c option in the examples. Maurice
Re: rdate(8) manpage clarification
On Thu, Apr 12, 2007 at 10:34:25PM +0200, Maurice Janssen wrote: Hi, The manpage for rdate(8) uses the -c option in the examples at the bottom (leap second correction), but the given host (ptbtime1.ptb.de) doesn't need this. In fact, I've never come across a time server that needed -c, but I suppose there are some servers out there that need it. Anyway, I think it's better to skip the -c option in the examples. Maurice why? if you need -c, you have it. if you don't, it won;t do any harm to specify it. as i understand it, -nc is a fair combination. jmc
Re: rdate(8) manpage clarification
On Thu, Apr 12, 2007 at 10:34:25PM +0200, Maurice Janssen wrote: The manpage for rdate(8) uses the -c option in the examples at the bottom (leap second correction), but the given host (ptbtime1.ptb.de) doesn't need this. SNTP gives time in UTC, but some sysadmins would prefer to synchronize their system time to TAI rather than UTC (e.g., so time values returned by gettimeofday(2) progresses normally during leap seconds). The -c argument for rdate is intended for their use. Basic rule of thumb is use -c if and only if you're using a timezone file under /usr/share/zoneinfo/right/ (i.e., one that includes leap second info). Otherwise your clock will most likely be off by 23 seconds.
