


 RRRRRRRRDDDDFFFFEEEETTTTCCCCHHHH((((1111))))                       1111....0000....44445555                        RRRRRRRRDDDDFFFFEEEETTTTCCCCHHHH((((1111))))
 rrrrrrrrddddttttoooooooollll                                                             rrrrrrrrddddttttoooooooollll
                                 2222000000003333----00004444----11116666



 NNNNAAAAMMMMEEEE
      rrdtool fetch - fetch data from an rrd.

 SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
      rrrrrrrrddddttttoooooooollll ffffeeeettttcccchhhh _f_i_l_e_n_a_m_e _C_F [--------rrrreeeessssoooolllluuuuttttiiiioooonnnn|----rrrr _r_e_s_o_l_u_t_i_o_n]
      [--------ssssttttaaaarrrrtttt|----ssss _s_t_a_r_t] [--------eeeennnndddd|----eeee _e_n_d]

 DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
      The ffffeeeettttcccchhhh function is normally used internally by the graph function,
      to get data from RRRRRRRRDDDDs. ffffeeeettttcccchhhh will analyze the RRRRRRRRDDDD and will try to
      retrieve the data in the resolution requested.  The data fetched is
      printed to stdout. *_U_N_K_N_O_W_N* data is often represented by the string
      "NaN" depending on your OSs printf function.

      _f_i_l_e_n_a_m_e
              the name of the RRRRRRRRDDDD you want to fetch the data from.

      _C_F      which consolidation function should have been applied to the
              data you want to fetch? (AVERAGE,MIN,MAX,LAST)

      --------rrrreeeessssoooolllluuuuttttiiiioooonnnn|----rrrr _r_e_s_o_l_u_t_i_o_n (default is the highest resolution)
              what interval should the values have (seconds per value).
              rrrrrrrrddddffffeeeettttcccchhhh will try to match your request, but it will return
              data even if no absolute match is possible. NNNNBBBB.... See note
              below.

      --------ssssttttaaaarrrrtttt|----ssss _s_t_a_r_t (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.

      --------eeeennnndddd|----eeee _e_n_d (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.

      RRRREEEESSSSOOOOLLLLUUUUTTTTIIIIOOOONNNN IIIINNNNTTTTEEEERRRRVVVVAAAALLLL

      In order to get rrdtool to fetch anything other than the finest
      resolution RRA bbbbooootttthhhh the start and end time must be specified on
      boundaries that are multiples of the wanted resolution. Consider the
      following example:









                                    - 1 -        Formatted:  August 20, 2003






 RRRRRRRRDDDDFFFFEEEETTTTCCCCHHHH((((1111))))                       1111....0000....44445555                        RRRRRRRRDDDDFFFFEEEETTTTCCCCHHHH((((1111))))
 rrrrrrrrddddttttoooooooollll                                                             rrrrrrrrddddttttoooooooollll
                                 2222000000003333----00004444----11116666



       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 NNNNOOOOTTTT
      in 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"'

      AAAATTTT----SSSSTTTTYYYYLLLLEEEE TTTTIIIIMMMMEEEE SSSSPPPPEEEECCCCIIIIFFFFIIIICCCCAAAATTTTIIIIOOOONNNN

      Apart from the traditional _S_e_c_o_n_d_s _s_i_n_c_e _e_p_o_c_h, rrdtool does also
      understand at-style time specification.  The specification is called
      "at-style" after Unix command _a_t(1) that has moderately complex ways
      to specify time to run your job at.  The at-style specification
      consists of two parts: TTTTIIIIMMMMEEEE RRRREEEEFFFFEEEERRRREEEENNNNCCCCEEEE specification and TTTTIIIIMMMMEEEE OOOOFFFFFFFFSSSSEEEETTTT



                                    - 2 -        Formatted:  August 20, 2003






 RRRRRRRRDDDDFFFFEEEETTTTCCCCHHHH((((1111))))                       1111....0000....44445555                        RRRRRRRRDDDDFFFFEEEETTTTCCCCHHHH((((1111))))
 rrrrrrrrddddttttoooooooollll                                                             rrrrrrrrddddttttoooooooollll
                                 2222000000003333----00004444----11116666



      specification.

      TTTTIIIIMMMMEEEE RRRREEEEFFFFEEEERRRREEEENNNNCCCCEEEE SSSSPPPPEEEECCCCIIIIFFFFIIIICCCCAAAATTTTIIIIOOOONNNN

      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 nnnnoooowwww. On
      its own part, time reference consists of _t_i_m_e-_o_f-_d_a_y reference (which
      should come first, if present) and _d_a_y reference.

      _T_i_m_e-_o_f-_d_a_y can be specified as HHHHHHHH::::MMMMMMMM, HHHHHHHH....MMMMMMMM, or just HHHHHHHH, you can
      suffix it with aaaammmm or ppppmmmm or use 24-hours clock. The few special times
      of day are understood as well, these include mmmmiiiiddddnnnniiiigggghhhhtttt (00:00), nnnnoooooooonnnn
      (12:00) and British tttteeeeaaaattttiiiimmmmeeee (16:00).

      The _d_a_y can be specified as _m_o_n_t_h-_n_a_m_e _d_a_y-_o_f-_t_h_e-_m_o_n_t_h and optional
      2- or 4-digit _y_e_a_r number (e.g. March 8 1999).  Alternatively, you can
      use _d_a_y-_o_f-_w_e_e_k-_n_a_m_e (e.g. Monday), or one of the words: yyyyeeeesssstttteeeerrrrddddaaaayyyy,
      ttttooooddddaaaayyyy, ttttoooommmmoooorrrrrrrroooowwww.  You can also specify _d_a_y as a full date in several
      numerical formats; these include: MMMMMMMM////DDDDDDDD////[[[[YYYYYYYY]]]]YYYYYYYY, DDDDDDDD....MMMMMMMM....[[[[YYYYYYYY]]]]YYYYYYYY,
      YYYYYYYYYYYYYYYYMMMMMMMMDDDDDDDD.

      _N_O_T_E_1: this is different from the original _a_t(1) behavior, which
      interprets a single-number date as MMDD[YY]YY.

      _N_O_T_E_2: if you specify _d_a_y this way, the _t_i_m_e-_o_f-_d_a_y is REQUIRED to be
      present.

      Finally, you can use words nnnnoooowwww, ssssttttaaaarrrrtttt, or eeeennnndddd as your time reference.
      NNNNoooowwww refers to the current moment (and is also a default time
      reference). SSSSttttaaaarrrrtttt (eeeennnndddd) can be used to specify time relative to the
      start (end) time for those tools that use these categories (rrdfetch,
      rrdgraph).

      Month and weekday names can be used in their naturally abbreviated
      form (e.g., Dec for December, Sun for Sunday, etc.). The words nnnnoooowwww,
      ssssttttaaaarrrrtttt, eeeennnndddd can be abbreviated to nnnn, ssss, eeee.

      TTTTIIIIMMMMEEEE OOOOFFFFFFFFSSSSEEEETTTT SSSSPPPPEEEECCCCIIIIFFFFIIIICCCCAAAATTTTIIIIOOOONNNN

      Time offset specification is used to add (or subtract) certain time
      interval to (from) the time reference moment. It consists of _s_i_g_n
      (++++ or ----) and _a_m_o_u_n_t. The following time units can be used to specify
      the _a_m_o_u_n_t: yyyyeeeeaaaarrrrssss, mmmmoooonnnntttthhhhssss, wwwweeeeeeeekkkkssss, ddddaaaayyyyssss, hhhhoooouuuurrrrssss, mmmmiiiinnnnuuuutttteeeessss, sssseeeeccccoooonnnnddddssss, 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.)




                                    - 3 -        Formatted:  August 20, 2003






 RRRRRRRRDDDDFFFFEEEETTTTCCCCHHHH((((1111))))                       1111....0000....44445555                        RRRRRRRRDDDDFFFFEEEETTTTCCCCHHHH((((1111))))
 rrrrrrrrddddttttoooooooollll                                                             rrrrrrrrddddttttoooooooollll
                                 2222000000003333----00004444----11116666



      _N_O_T_E_3: 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
      reference, 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 _m_k_t_i_m_e(3) will take care of this later).  This may lead to
      some surprising (or even invalid!) results, e.g. 'May 31 -1month' =
      'Apr 31' (meaningless) = 'May 1' (after _m_k_t_i_m_e(3) normalization); in
      the EET timezone '3:30am Mar 29 1999 -1 day' yields '3:30am Mar 28
      1999' (Sunday) 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 adjustment 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)

      _N_O_T_E_4: The single-letter abbreviation for both mmmmoooonnnntttthhhhssss and mmmmiiiinnnnuuuutttteeeessss is
      mmmm. To disambiguate, the parser tries to read your mind :) by applying
      the following two heuristics:

      1  If mmmm is used in context of (i.e. right after the) years, months,
         weeks, or days it is assumed to mean mmmmoooonnnntttthhhhssss, while in the context
         of hours, minutes, and seconds it means minutes.  (e.g., in -1y6m
         or +3w1m mmmm means mmmmoooonnnntttthhhhssss, while in -3h20m or +5s2m mmmm means mmmmiiiinnnnuuuutttteeeessss)

      2  Out of context (i.e. right after the ++++ or ---- sign) the meaning of mmmm
         is guessed from the number it directly follows.  Currently, if the
         number absolute value is below 25 it is assumed that mmmm means
         mmmmoooonnnntttthhhhssss, otherwise it is treated as mmmmiiiinnnnuuuutttteeeessss.  (e.g., -25m == -25
         minutes, while +24m == +24 months)

      _F_i_n_a_l _N_O_T_E_S: 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)

      TTTTIIIIMMMMEEEE SSSSPPPPEEEECCCCIIIIFFFFIIIICCCCAAAATTTTIIIIOOOONNNN EEEEXXXXAAAAMMMMPPPPLLLLEEEESSSS

      _O_c_t _1_2 -- October 12 this year




                                    - 4 -        Formatted:  August 20, 2003






 RRRRRRRRDDDDFFFFEEEETTTTCCCCHHHH((((1111))))                       1111....0000....44445555                        RRRRRRRRDDDDFFFFEEEETTTTCCCCHHHH((((1111))))
 rrrrrrrrddddttttoooooooollll                                                             rrrrrrrrddddttttoooooooollll
                                 2222000000003333----00004444----11116666



      -_1_m_o_n_t_h or -_1_m -- current time of day, only a month before (may yield
      surprises, see the NOTE3 above)

      _n_o_o_n _y_e_s_t_e_r_d_a_y -_3_h_o_u_r_s -- yesterday morning; can be put also as
      _9_a_m-_1_d_a_y

      _2_3:_5_9 _3_1._1_2._1_9_9_9 -- 1 minute to the year 2000

      _1_2/_3_1/_9_9 _1_1:_5_9_p_m -- 1 minute to the year 2000 for imperialists

      _1_2_a_m _0_1/_0_1/_0_1 -- start of the new millennium

      _e_n_d-_3_w_e_e_k_s or _e-_3_w -- 3 weeks before end time (may be used as start
      time specification)

      _s_t_a_r_t+_6_h_o_u_r_s or _s+_6_h -- 6 hours after start time (may be used as end
      time specification)

      _9_3_1_2_2_5_5_3_7 -- 18:45  July 5th, 1999 (yes, seconds since 1970 are valid
      as well)

      _1_9_9_7_0_7_0_3 _1_2:_4_5 -- 12:45  July 3th, 1997 (my favorite, and its even got
      an ISO number (8601))

 AAAAUUUUTTTTHHHHOOOORRRR
      Tobias Oetiker <oetiker@ee.ethz.ch>



























                                    - 5 -        Formatted:  August 20, 2003



