{ "content": [ { "type": "text", "text": "# rrdfetch (man)\n\n## NAME\n\nrrdfetch - Fetch data from an RRD.\n\n## SYNOPSIS\n\nrrdtool fetch filename CF [--resolution|-r resolution] [--start|-s start] [--end|-e end]\n[--align-start|-a] [--daemon|-d address]\n\n## DESCRIPTION\n\nThe fetch function is normally used internally by the graph function to get data from RRDs.\nfetch will analyze the RRD and try to retrieve the data in the resolution requested. The\ndata fetched is printed to stdout. *UNKNOWN* data is often represented by the string \"NaN\"\ndepending on your OS's printf function.\n\n## Sections\n\n- **NAME**\n- **SYNOPSIS**\n- **DESCRIPTION**\n- **ENVIRONMENT VARIABLES**\n- **AUTHOR**\n\nUse structuredContent.sections for detailed options, examples, and full documentation.\n" } ], "structuredContent": { "command": "rrdfetch", "section": "", "mode": "man", "summary": "rrdfetch - Fetch data from an RRD.", "synopsis": "rrdtool fetch filename CF [--resolution|-r resolution] [--start|-s start] [--end|-e end]\n[--align-start|-a] [--daemon|-d address]", "tldr_summary": null, "tldr_examples": [], "tldr_source": null, "flags": [], "examples": [], "see_also": [], "section_outline": [ { "name": "NAME", "lines": 2, "subsections": [] }, { "name": "SYNOPSIS", "lines": 3, "subsections": [] }, { "name": "DESCRIPTION", "lines": 212, "subsections": [] }, { "name": "ENVIRONMENT VARIABLES", "lines": 7, "subsections": [] }, { "name": "AUTHOR", "lines": 3, "subsections": [] } ], "sections": { "NAME": { "content": "rrdfetch - Fetch data from an RRD.\n", "subsections": [] }, "SYNOPSIS": { "content": "rrdtool fetch filename CF [--resolution|-r resolution] [--start|-s start] [--end|-e end]\n[--align-start|-a] [--daemon|-d address]\n", "subsections": [] }, "DESCRIPTION": { "content": "The fetch function is normally used internally by the graph function to get data from RRDs.\nfetch will analyze the RRD and try to retrieve the data in the resolution requested. The\ndata fetched is printed to stdout. *UNKNOWN* data is often represented by the string \"NaN\"\ndepending on your OS's printf function.\n\nfilename\nthe name of the RRD you want to fetch the data from.\n\nCF the consolidation function that is applied to the data you want to fetch\n(AVERAGE,MIN,MAX,LAST)\n\n--resolution|-r resolution (default is the highest resolution)\nthe interval you want the values to have (seconds per value). An optional suffix may\nbe used (e.g. \"5m\" instead of 300 seconds). rrdfetch will try to match your request,\nbut it will return data even if no absolute match is possible. See \"RESOLUTION\nINTERVAL\".\n\n--start|-s start (default end-1day)\nstart of the time series. A time in seconds since epoch (1970-01-01) is required.\nNegative numbers are relative to the current time. By default, one day worth of data\nwill be fetched. See also \"AT-STYLE TIME SPECIFICATION\" for a detailed explanation on\nways to specify the start time.\n\n--end|-e end (default now)\nthe end of the time series in seconds since epoch. See also \"AT-STYLE TIME\nSPECIFICATION\" for a detailed explanation of how to specify the end time.\n\n--align-start|-a\nAutomatically adjust the start time down to be aligned with the resolution. The end-\ntime is adjusted by the same amount. This avoids the need for external calculations\ndescribed in RESOLUTION INTERVAL, though if a specific RRA is desired this will not\nensure the start and end fall within its bounds.\n\n--daemon|-d address\nAddress of the rrdcached daemon. If specified, a \"flush\" command is sent to the\nserver before reading the RRD files. This allows rrdtool to return fresh data even if\nthe daemon is configured to cache values for a long time. For a list of accepted\nformats, see the -l option in the rrdcached manual.\n\nrrdtool fetch --daemon unix:/var/run/rrdcached.sock /var/lib/rrd/foo.rrd AVERAGE\n\nPlease note that due to thread-safety reasons, the time specified with -s and -e\ncannot use the complex forms described in \"AT-STYLE TIME SPECIFICATION\". The only\naccepted arguments are \"simple integers\". Positive values are interpreted as seconds\nsince epoch, negative values (and zero) are interpreted as relative to now. So\n\"1272535035\" refers to \"09:57:15 (UTC), April 29th 2010\" and \"-3600\" means \"one hour\nago\".\n\nRESOLUTION INTERVAL\nIn order to get RRDtool to fetch anything other than the finest resolution RRA both the start\nand end time must be specified on boundaries that are multiples of the desired resolution.\nConsider the following example:\n\nrrdtool create subdata.rrd -s 10 \\\nDS:ds0:GAUGE:5m:0:U \\\nRRA:AVERAGE:0.5:5m:300h \\\nRRA:AVERAGE:0.5:15m:300h \\\nRRA:AVERAGE:0.5:1h:50d \\\nRRA:MAX:0.5:1h:50d \\\nRRA:AVERAGE:0.5:1d:600d \\\nRRA:MAX:0.5:1d:600d\n\nThis RRD collects data every 10 seconds and stores its averages over 5 minutes, 15 minutes, 1\nhour, and 1 day, as well as the maxima for 1 hour and 1 day.\n\nConsider now that you want to fetch the 15 minute average data for the last hour. You might\ntry\n\nrrdtool fetch subdata.rrd AVERAGE -r 15m -s -1h\n\nHowever, this will almost always result in a time series that is NOT in the 15 minute RRA.\nTherefore, the highest resolution RRA, i.e. 5 minute averages, will be chosen which in this\ncase is not what you want.\n\nHence, make sure that\n\n1. both start and end time are a multiple of 900 (\"15m\")\n\n2. both start and end time are within the desired RRA\n\nSo, if time now is called \"t\", do\n\nend time == int(t/900)*900,\nstart time == end time - 1hour,\nresolution == 900.\n\nUsing the bash shell, this could look be:\n\nTIME=$(date +%s)\nRRDRES=900\nrrdtool fetch subdata.rrd AVERAGE -r $RRDRES \\\n-e $(($TIME/$RRDRES*$RRDRES)) -s e-1h\n\nOr in Perl:\n\nperl -e '$ctime = time; $rrdres = 900; \\\nsystem \"rrdtool fetch subdata.rrd AVERAGE \\\n-r $rrdres -e @{[int($ctime/$rrdres)*$rrdres]} -s e-1h\"'\n\nOr using the --align-start flag:\n\nrrdtool fetch subdata.rrd AVERAGE -a -r 15m -s -1h\n\nAT-STYLE TIME SPECIFICATION\nApart from the traditional Seconds since epoch, RRDtool does also understand at-style time\nspecification. The specification is called \"at-style\" after the Unix command at(1) that has\nmoderately complex ways to specify time to run your job at a certain date and time. The at-\nstyle specification consists of two parts: the TIME REFERENCE specification and the TIME\nOFFSET specification.\n\nTIME REFERENCE SPECIFICATION\nThe time reference specification is used, well, to establish a reference moment in time (to\nwhich the time offset is then applied to). When present, it should come first, when omitted,\nit defaults to now. On its own part, time reference consists of a time-of-day reference\n(which should come first, if present) and a day reference.\n\nThe time-of-day can be specified as HH:MM, HH.MM, or just HH. You can suffix it with am or pm\nor use 24-hours clock. Some special times of day are understood as well, including midnight\n(00:00), noon (12:00) and British teatime (16:00).\n\nThe day can be specified as month-name day-of-the-month and optional a 2- or 4-digit year\nnumber (e.g. March 8 1999). Alternatively, you can use day-of-week-name (e.g. Monday), or one\nof the words: yesterday, today, tomorrow. You can also specify the day as a full date in\nseveral numerical formats, including MM/DD/[YY]YY, DD.MM.[YY]YY, or YYYYMMDD.\n\nNOTE1: this is different from the original at(1) behavior, where a single-number date is\ninterpreted as MMDD[YY]YY.\n\nNOTE2: if you specify the day in this way, the time-of-day is REQUIRED as well.\n\nFinally, you can use the words now, start, end or epoch as your time reference. Now refers to\nthe current moment (and is also the default time reference). Start (end) can be used to\nspecify a time relative to the start (end) time for those tools that use these categories\n(rrdfetch, rrdgraph) and epoch indicates the *IX epoch (*IX timestamp 0 = 1970-01-01 00:00:00\nUTC). epoch is useful to disambiguate between a timestamp value and some forms of abbreviated\ndate/time specifications, because it allows one to use time offset specifications using\nunits, eg. epoch+19711205s unambiguously denotes timestamp 19711205 and not 1971-12-05\n00:00:00 UTC.\n\nMonth and day of the week names can be used in their naturally abbreviated form (e.g., Dec\nfor December, Sun for Sunday, etc.). The words now, start, end can be abbreviated as n, s, e.\n\nTIME OFFSET SPECIFICATION\nThe time offset specification is used to add/subtract certain time intervals to/from the time\nreference moment. It consists of a sign (+ or -) and an amount. The following time units can\nbe used to specify the amount: years, months, weeks, days, hours, minutes, or seconds. These\nunits can be used in singular or plural form, and abbreviated naturally or to a single letter\n(e.g. +3days, -1wk, -3y). Several time units can be combined (e.g., -5mon1w2d) or\nconcatenated (e.g., -5h45min = -5h-45min = -6h+15min = -7h+1h30m-15min, etc.)\n\nNOTE3: If you specify time offset in days, weeks, months, or years, you will end with the\ntime offset that may vary depending on your time reference, because all those time units have\nno single well defined time interval value (1 year contains either 365 or 366 days, 1 month\nis 28 to 31 days long, and even 1 day may be not equal to 24 hours twice a year, when DST-\nrelated clock adjustments take place). To cope with this, when you use days, weeks, months,\nor years as your time offset units your time reference date is adjusted accordingly without\ntoo much further effort to ensure anything about it (in the hope that mktime(3) will take\ncare of this later). This may lead to some surprising (or even invalid!) results, e.g.\n'May 31 -1month' = 'Apr 31' (meaningless) = 'May 1' (after mktime(3) normalization); in the\nEET timezone '3:30am Mar 29 1999 -1 day' yields '3:30am Mar 28 1999' (Sunday) which is an\ninvalid time/date combination (because of 3am -> 4am DST forward clock adjustment, see the\nbelow example).\n\nIn contrast, hours, minutes, and seconds are well defined time intervals, and these are\nguaranteed to always produce time offsets exactly as specified (e.g. for EET timezone,\n'8:00 Mar 27 1999 +2 days' = '8:00 Mar 29 1999', but since there is 1-hour DST forward clock\nadjustment that occurs around 3:00 Mar 28 1999, the actual time interval between\n8:00 Mar 27 1999 and 8:00 Mar 29 1999 equals 47 hours; on the other hand,\n'8:00 Mar 27 1999 +48 hours' = '9:00 Mar 29 1999', as expected)\n\nNOTE4: The single-letter abbreviation for both months and minutes is m. To disambiguate them,\nthe parser tries to read your mind :) by applying the following two heuristics:\n\n1. If m is used in context of (i.e. right after the) years, months, weeks, or days it is\nassumed to mean months, while in the context of hours, minutes, and seconds it means\nminutes. (e.g., in -1y6m or +3w1m m is interpreted as months, while in -3h20m or +5s2m m\nthe parser decides for minutes).\n\n2. Out of context (i.e. right after the + or - sign) the meaning of m is guessed from the\nnumber it directly follows. Currently, if the number's absolute value is below 6 it is\nassumed that m means months, otherwise it is treated as minutes. (e.g., -6m == -6m\nminutes, while +5m == +5 months)\n\nFinal NOTES: Time specification is case-insensitive. Whitespace can be inserted freely or\nomitted altogether. There are, however, cases when whitespace is required (e.g.,\n'midnight Thu'). In this case you should either quote the whole phrase to prevent it from\nbeing taken apart by your shell or use '' (underscore) or ',' (comma) which also count as\nwhitespace (e.g., midnightThu or midnight,Thu).\n\nTIME SPECIFICATION EXAMPLES\nOct 12 -- October 12 this year\n\n-1month or -1m -- current time of day, only a month before (may yield surprises, see NOTE3\nabove).\n\nnoon yesterday -3hours -- yesterday morning; can also be specified as 9am-1day.\n\n23:59 31.12.1999 -- 1 minute to the year 2000.\n\n12/31/99 11:59pm -- 1 minute to the year 2000 for imperialists.\n\n12am 01/01/01 -- start of the new millennium\n\nend-3weeks or e-3w -- 3 weeks before end time (may be used as start time specification).\n\nstart+6hours or s+6h -- 6 hours after start time (may be used as end time specification).\n\n931200300 -- 18:45 (UTC), July 5th, 1999 (yes, seconds since 1970 are valid as well).\n\n19970703 12:45 -- 12:45 July 3th, 1997 (my favorite, and it has even got an ISO number\n(8601)).\n", "subsections": [] }, "ENVIRONMENT VARIABLES": { "content": "The following environment variables may be used to change the behavior of \"rrdtool fetch\":\n\nRRDCACHEDADDRESS\nIf this environment variable is set it will have the same effect as specifying the\n\"--daemon\" option on the command line. If both are present, the command line argument\ntakes precedence.\n", "subsections": [] }, "AUTHOR": { "content": "Tobias Oetiker \n\n1.7.2 2024-03-31 RRDFETCH(1)", "subsections": [] } } } }