RRDFETCH(1)                         rrdtool                        RRDFETCH(1)



[1mNAME[0m
       rrdtool fetch - fetch data from an rrd.

[1mSYNOPSIS[0m
       [1mrrdtool fetch [4m[22mfilename[24m [4mCF[24m [[1m--resolution[22m|[1m-r [4m[22mresolution[24m]
       [[1m--start[22m|[1m-s [4m[22mstart[24m] [[1m--end[22m|[1m-e [4m[22mend[24m]

[1mDESCRIPTION[0m
       The [1mfetch [22mfunction is normally used internally by the graph function,
       to get data from [1mRRD[22ms. [1mfetch [22mwill analyze the [1mRRD [22mand will try to
       retrieve the data in the resolution requested.  The data fetched is
       printed to stdout. [4m*UNKNOWN*[24m data is often represented by the string
       "NaN" depending on your OSs printf function.

       [4mfilename[0m
               the name of the [1mRRD [22myou want to fetch the data from.

       [4mCF[24m      which consolidation function should have been applied to the
               data you want to fetch? (AVERAGE,MIN,MAX,LAST)

       [1m--resolution[22m|[1m-r [4m[22mresolution[24m (default is the highest resolution)
               what interval should the values have (seconds per value). [1mrrd-[0m
               [1mfetch [22mwill try to match your request, but it will return data
               even if no absolute match is possible. [1mNB. [22mSee note below.

       [1m--start[22m|[1m-s [4m[22mstart[24m (default end-1day)
               when should the data begin. A time in seconds since epoch
               (1970-01-01) is required. Negative numbers are relative to the
               current time. By default one day worth of data will be fetched.
               See also AT-STYLE TIME SPECIFICATION section for a detailed
               explanation on  ways to specify start time.

       [1m--end[22m|[1m-e [4m[22mend[24m (default now)
               when should the data end. Time in seconds since epoch. See also
               AT-STYLE TIME SPECIFICATION section for a detailed explanation
               of how to specify end time.

       [1mRESOLUTION INTERVAL[0m

       In order to get rrdtool to fetch anything other than the finest resolu-
       tion RRA [1mboth [22mthe start and end time must be specified on boundaries
       that are multiples of the wanted resolution. Consider the following
       example:

        rrdtool create subdata.rrd -s 10 DS:ds0:GAUGE:300:0:U \
         RRA:AVERAGE:0.5:30:3600 \
         RRA:AVERAGE:0.5:90:1200 \
         RRA:AVERAGE:0.5:360:1200 \
         RRA:MAX:0.5:360:1200 \
         RRA:AVERAGE:0.5:8640:600 \
         RRA:MAX:0.5:8640:600

       This RRD collects data every 10 seconds and stores its averages over 5
       minutes, 15 minutes, 1 hour and 1 day as well as the maxima for 1 hour
       and 1 day.

       Consider now that you want too fetch the 15 minute average data for
       last hour.  So you might try

        rrdtool fetch subdata.rrd AVERAGE -r 900 -s -1h

       However, this will almost always result in a time series that is [1mNOT [22min
       the 15 minute RRA. Therefore the highest resolution RRA, i.e. 5 minute
       averages, will be chosen which, in this case, is not what you want.

       Hence, make sure that

       1. both start and end time are a multiple of 900

       2. both start and end time are within the wanted RRA

       So, if time now is called "t",

        do end time == int(t/900)*900,
        start time == end time -1hour, resolution == 900.

       In e.g. bash this could look as:

        TIME=$(date +%s); RRDRES=900; rrdtool fetch subdata.rrd AVERAGE -r $RRDRES \
        -e $(echo $(($TIME/$RRDRES*$RRDRES))) -s e-1h

       Or in perl:

        perl -e '$ctime = time; $rrdres = 900; system "rrdtool fetch subdata.rrd AVERAGE \
        -r $rrdres -e @{[int($ctime/$rrdres)*$rrdres]} -s e-1h"'

       [1mAT-STYLE TIME SPECIFICATION[0m

       Apart from the traditional [4mSeconds[24m [4msince[24m [4mepoch[24m, rrdtool does also
       understand at-style time specification.  The specification is called
       "at-style" after Unix command [4mat[24m(1) that has moderately complex ways to
       specify time to run your job at.  The at-style specification consists
       of two parts: [1mTIME REFERENCE [22mspecification and [1mTIME OFFSET [22mspecifica-
       tion.

       [1mTIME REFERENCE SPECIFICATION[0m

       Time reference specification is used, well,... to establish a reference
       moment in time (for time offset to be applied to). When present, it
       should come first, when omitted, it defaults to [1mnow[22m. On its own part,
       time reference consists of [4mtime-of-day[24m reference (which should come
       first, if present) and [4mday[24m reference.

       [4mTime-of-day[24m can be specified as [1mHH:MM[22m, [1mHH.MM[22m, or just [1mHH[22m, you can suf-
       fix it with [1mam [22mor [1mpm [22mor use 24-hours clock. The few special times of
       day are understood as well, these include [1mmidnight [22m(00:00), [1mnoon[0m
       (12:00) and British [1mteatime [22m(16:00).

       The [4mday[24m can be specified as [4mmonth-name[24m [4mday-of-the-month[24m and optional 2-
       or 4-digit [4myear[24m number (e.g. March 8 1999).  Alternatively, you can use
       [4mday-of-week-name[24m (e.g. Monday), or one of the words: [1myesterday[22m, [1mtoday[22m,
       [1mtomorrow[22m.  You can also specify [4mday[24m as a full date in several numerical
       formats; these include: [1mMM/DD/[YY]YY[22m, [1mDD.MM.[YY]YY[22m, [1mYYYYMMDD[22m.

       [4mNOTE1[24m: this is different from the original [4mat[24m(1) behavior, which inter-
       prets a single-number date as MMDD[YY]YY.

       [4mNOTE2[24m: if you specify [4mday[24m this way, the [4mtime-of-day[24m is REQUIRED to be
       present.

       Finally, you can use words [1mnow[22m, [1mstart[22m, or [1mend [22mas your time reference.
       [1mNow [22mrefers to the current moment (and is also a default time refer-
       ence). [1mStart [22m([1mend[22m) can be used to specify time relative to the start
       (end) time for those tools that use these categories (rrdfetch, rrd-
       graph).

       Month and weekday names can be used in their naturally abbreviated form
       (e.g., Dec for December, Sun for Sunday, etc.). The words [1mnow[22m, [1mstart[22m,
       [1mend [22mcan be abbreviated to [1mn[22m, [1ms[22m, [1me[22m.

       [1mTIME OFFSET SPECIFICATION[0m

       Time offset specification is used to add (or subtract) certain time
       interval to (from) the time reference moment. It consists of [4msign[0m
       ([1m+ [22mor [1m-[22m) and [4mamount[24m. The following time units can be used to specify
       the [4mamount[24m: [1myears[22m, [1mmonths[22m, [1mweeks[22m, [1mdays[22m, [1mhours[22m, [1mminutes[22m, [1mseconds[22m, these
       can be used in singular or plural form, and abbreviated naturally or to
       a single letter (e.g. +3days, -1wk, -3y). Several time units can be
       combined together (e.g., -5mon1w2d), as well as several time offsets
       can be concatenated (e.g., -5h45min = -5h-45min = -6h+15min =
       -7h+1h30m-15min, etc.)

       [4mNOTE3[24m: If you specify time offset in days, weeks, months, or years, you
       will end with the time offset that may vary depending on you time ref-
       erence, because all those time units have no single well defined time
       interval value (1 year contains either 365 or 366 days, 1 month is 28
       to 31 days long, and even 1 day may be not equal to 24 hours twice a
       year, when DST-related clock adjustments take place).  To cope with
       this, when you use days, weeks, months, or years as your time offset
       units your time reference date is adjusted accordingly without taking
       too much further effort to ensure anything about it (in the hope that
       [4mmktime[24m(3) will take care of this later).  This may lead to some sur-
       prising (or even invalid!) results, e.g. 'May 31 -1month' = 'Apr 31'
       (meaningless) = 'May 1' (after [4mmktime[24m(3) normalization); in the EET
       timezone '3:30am Mar 29 1999 -1 day' yields '3:30am Mar 28 1999' (Sun-
       day) which is invalid time/date combination (because of 3am -> 4am DST
       forward clock adjustment, see the below example).  On the other hand,
       hours, minutes, and seconds are well defined time intervals, and these
       are guaranteed to always produce time offsets exactly as specified
       (e.g. for EET timezone, '8:00 Mar 27 1999 +2 days' =
       '8:00 Mar 29 1999', but since there is 1-hour DST forward clock adjust-
       ment takes place around 3:00 Mar 28 1999, the actual time interval
       between 8:00 Mar 27 1999 and 8:00 Mar 29 1999 equals 47 hours; on the
       other hand, '8:00 Mar 27 1999 +48 hours' = '9:00 Mar 29 1999', as
       expected)

       [4mNOTE4[24m: The single-letter abbreviation for both [1mmonths [22mand [1mminutes [22mis [1mm[22m.
       To disambiguate, the parser tries to read your mind :) by applying the
       following two heuristics:

       1  If [1mm [22mis used in context of (i.e. right after the) years, months,
          weeks, or days it is assumed to mean [1mmonths[22m, while in the context of
          hours, minutes, and seconds it means minutes.  (e.g., in -1y6m or
          +3w1m [1mm [22mmeans [1mmonths[22m, while in -3h20m or +5s2m [1mm [22mmeans [1mminutes[22m)

       2  Out of context (i.e. right after the [1m+ [22mor [1m- [22msign) the meaning of [1mm[0m
          is guessed from the number it directly follows.  Currently, if the
          number absolute value is below 25 it is assumed that [1mm [22mmeans [1mmonths[22m,
          otherwise it is treated as [1mminutes[22m.  (e.g., -25m == -25 minutes,
          while +24m == +24 months)

       [4mFinal[24m [4mNOTES[24m: Time specification is case-insensitive.  Whitespace can be
       inserted freely or omitted altogether, there are, however, cases when
       whitespace is required (e.g., 'midnight Thu'). In this case you should
       either quote the whole phrase to prevent it from being taken apart by
       your shell or use '_' (underscore) or ',' (comma) which also count as
       whitespace (e.g., midnight_Thu or midnight,Thu)

       [1mTIME SPECIFICATION EXAMPLES[0m

       [4mOct[24m [4m12[24m -- October 12 this year

       [4m-1month[24m or [4m-1m[24m -- current time of day, only a month before (may yield
       surprises, see the NOTE3 above)

       [4mnoon[24m [4myesterday[24m [4m-3hours[24m -- yesterday morning; can be put also as
       [4m9am-1day[0m

       [4m23:59[24m [4m31.12.1999[24m -- 1 minute to the year 2000

       [4m12/31/99[24m [4m11:59pm[24m -- 1 minute to the year 2000 for imperialists

       [4m12am[24m [4m01/01/01[24m -- start of the new millennium

       [4mend-3weeks[24m or [4me-3w[24m -- 3 weeks before end time (may be used as start
       time specification)

       [4mstart+6hours[24m or [4ms+6h[24m -- 6 hours after start time (may be used as end
       time specification)

       [4m931225537[24m -- 18:45  July 5th, 1999 (yes, seconds since 1970 are valid
       as well)

       [4m19970703[24m [4m12:45[24m -- 12:45  July 3th, 1997 (not quote standard, but I love
       this ...)

[1mAUTHOR[0m
       Tobias Oetiker <oetiker@ee.ethz.ch>



1.0.41                            2002-07-31                       RRDFETCH(1)
