RRDFETCH(1)                         rrdtool                        RRDFETCH(1)

NAME
       rrdfetch - Fetch data from an RRD.

SYNOPSIS
       rrdtool fetch filename CF [--resolution|-r resolution]
       [--start|-s start] [--end|-e end] [--align-start|-a]
       [--daemon|-d address]

DESCRIPTION
       The fetch function is normally used internally by the graph function to
       get data from RRRRDDs. fetch will analyze the RRD and try to retrieve the
       data in the resolution requested.  The data fetched is printed to
       stdout. *UNKNOWN* data is often represented by the string "NaN"
       depending on your OS's printf function.

       filename
               the name of the RRD you want to fetch the data from.

       CF      the consolidation function that is applied to the data you want
               to fetch (AVERAGE,MIN,MAX,LAST)

       --resolution|-r resolution (default is the highest resolution)
               the  interval  you want the values to have (seconds per value).
               An optional suffix may  be  used  (e.g.  "5m"  instead  of  300
               seconds).  rrdfetch will try to match your request, but it will
               return  data  even  if  no  absolute  match  is  possible.  See
               "RESOLUTION INTERVAL".

       --start|-s start (default end-1day)
               start of the  time  series.  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" for a detailed
               explanation on  ways to specify the start time.

       --end|-e end (default now)
               the end of the time series in seconds  since  epoch.  See  also
               "AT-STYLE TIME SPECIFICATION" for a detailed explanation of how
               to specify the end time.

       --align-start|-a
               Automatically adjust the start time down to be aligned with the
               resolution.  The end-time is adjusted by the same amount.  This
               avoids   the   need  for  external  calculations  described  in
               RESOLUTION INTERVAL, though if a specific RRA is  desired  this
               will not ensure the start and end fall within its bounds.

       --daemon|-d address
               Address  of  the  rrdcached  daemon.  If  specified,  a "flush"
               command is sent to the server before  reading  the  RRD  files.
               This  allows rrdtool to return fresh data even if the daemon is
               configured to cache values for a long  time.   For  a  list  of
               accepted formats, see the -l option in the rrdcached manual.

                rrdtool fetch --daemon unix:/var/run/rrdcached.sock /var/lib/rrd/foo.rrd AVERAGE

               Please  note  that  due  to  thread-safety  reasons,  the  time
               specified with -s and -e cannot use the complex forms described
               in "AT-STYLE TIME SPECIFICATION". The only  accepted  arguments
               are  "simple  integers".  Positive  values  are  interpreted as
               seconds since epoch, negative values (and zero) are interpreted
               as relative to now. So "1272535035" refers to "09:57:15  (UTC),
               April 29th 2010" and "-3600" means "one hour ago".

   RESOLUTION INTERVAL
       In  order  to  get  RRDtool  to  fetch  anything  other than the finest
       resolution RRA both the  start  and  end  time  must  be  specified  on
       boundaries  that  are multiples of the desired resolution. Consider the
       following example:

        rrdtool create subdata.rrd -s 10 \
         DS:ds0:GAUGE:5m:0:U \
         RRA:AVERAGE:0.5:5m:300h \
         RRA:AVERAGE:0.5:15m:300h \
         RRA:AVERAGE:0.5:1h:50d \
         RRA:MAX:0.5:1h:50d \
         RRA:AVERAGE:0.5:1d:600d \
         RRA:MAX:0.5:1d:600d

       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 to fetch the 15 minute average data for  the
       last hour.  You might try

        rrdtool fetch subdata.rrd AVERAGE -r 15m -s -1h

       However, this will almost always result in a time series that is NOT 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 ("15m")

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

       So, if time now is called "t", do

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

       Using the bash shell, this could look be:

        TIME=$(date +%s)
        RRDRES=900
        rrdtool fetch subdata.rrd AVERAGE -r $RRDRES \
           -e $(($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"'

       Or using the --align-start flag:

        rrdtool fetch subdata.rrd AVERAGE -a -r 15m -s -1h

   AT-STYLE TIME SPECIFICATION
       Apart  from  the  traditional  Seconds  since  epoch, RRDtool does also
       understand at-style time specification.  The  specification  is  called
       "at-style"  after  the  Unix  command at(1) that has moderately complex
       ways to specify time to run your job at a certain date  and  time.  The
       at-style  specification  consists  of  two  parts:  the  TIME REFERENCE
       specification and the TIME OFFSET specification.

   TIME REFERENCE SPECIFICATION
       The  time  reference  specification  is  used,  well,  to  establish  a
       reference moment in time (to which the time offset is then applied to).
       When  present,  it should come first, when omitted, it defaults to now.
       On its own part, time reference consists  of  a  time-of-day  reference
       (which should come first, if present) and a day reference.

       The  time-of-day  can be specified as HH:MM, HH.MM, or just HHHH. You can
       suffix it with am or pm or use 24-hours clock. Some  special  times  of
       day  are  understood  as well, including midnight (00:00), noon (12:00)
       and British teatime (16:00).

       The day can be specified as month-name day-of-the-month and optional  a
       2-  or  4-digit year number (e.g. March 8 1999). Alternatively, you can
       use day-of-week-name (e.g. Monday), or one  of  the  words:  yesterday,
       today, tomorrow. You can also specify the day as a full date in several
       numerical formats, including MM/DD/[YY]YY, DD.MM.[YY]YY, or YYYYYYYYMMMMDDDD.

       NOTE1:  this  is  different  from  the original at(1) behavior, where a
       single-number date is interpreted as MD[YY]YY.

       NOTE2: if you specify the day in this way, the time-of-day is  REQUIRED
       as well.

       Finally,  you  can  use the words now, start, end or epoch as your time
       reference. Now refers to the current moment (and is  also  the  default
       time  reference). Start (end) can be used to specify a time relative to
       the start  (end)  time  for  those  tools  that  use  these  categories
       (rrdfetch, rrdgraph) and epoch indicates the *IX epoch (*IX timestamp 0
       =  1970-01-01  00:00:00 UTC). epoch is useful to disambiguate between a
       timestamp value and some forms of abbreviated date/time specifications,
       because it allows one to use time offset  specifications  using  units,
       eg.  epoch+19711205s  unambiguously  denotes timestamp 19711205 and not
       1971-12-05 00:00:00 UTC.

       Month and day of  the  week  names  can  be  used  in  their  naturally
       abbreviated  form  (e.g.,  Dec for December, Sun for Sunday, etc.). The
       words now, start, end can be abbreviated as nn, ss, ee.

   TIME OFFSET SPECIFICATION
       The time offset specification is  used  to  add/subtract  certain  time
       intervals  to/from  the  time  reference  moment. It consists of a sign
       (++ or --) and an amount. The following time units can be used to specify
       the amount: years, months, weeks, days,  hours,  minutes,  or  seconds.
       These  units  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 (e.g., -5mon1w2d) or concatenated (e.g., -5h45min
       = -5h-45min = -6h+15min = -7h+1h30m-15min, etc.)

       NOTE3: If you specify time offset in days, weeks, months, or years, you
       will  end  with  the  time  offset that may vary depending on your 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 too much
       further  effort to ensure anything about it (in the hope that mktime(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 mktime(3) normalization); in the EET timezone  '3:30am
       Mar  29  1999  -1 day' yields '3:30am Mar 28 1999' (Sunday) which is an
       invalid time/date combination (because of 3am -> 4am DST forward  clock
       adjustment, see the below example).

       In  contrast,  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  that  occurs  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)

       NOTE4: The single-letter abbreviation for both months and minutes is mm.
       To disambiguate them, the parser tries to read your mind :) by applying
       the following two heuristics:

       1. If mm is used in context of (i.e. right  after  the)  years,  months,
          weeks, or days it is assumed to mean months, while in the context of
          hours,  minutes,  and  seconds it means minutes.  (e.g., in -1y6m or
          +3w1m mm is interpreted as months, while in -3h20m  or  +5s2m  mm  the
          parser decides for minutes).

       2. Out  of  context (i.e. right after the ++ or -- sign) the meaning of mm
          is guessed from the number it directly follows.  Currently,  if  the
          number's  absolute  value  is  below  6  it  is assumed that mm means
          months, otherwise it is treated  as  minutes.   (e.g.,  -6m  ==  -6m
          minutes, while +5m == +5 months)

       Final NOTES: 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).

   TIME SPECIFICATION EXAMPLES
       Oct 12 -- October 12 this year

       -1month  or  -1m -- current time of day, only a month before (may yield
       surprises, see NOTE3 above).

       noon yesterday -3hours -- yesterday morning; can also be  specified  as
       9am-1day.

       23:59 31.12.1999 -- 1 minute to the year 2000.

       12/31/99 11:59pm -- 1 minute to the year 2000 for imperialists.

       12am 01/01/01 -- start of the new millennium

       end-3weeks  or  e-3w  --  3 weeks before end time (may be used as start
       time specification).

       start+6hours or s+6h -- 6 hours after start time (may be  used  as  end
       time specification).

       931200300  --  18:45 (UTC), July 5th, 1999 (yes, seconds since 1970 are
       valid as well).

       19970703 12:45 -- 12:45  July 3th, 1997 (my favorite, and it  has  even
       got an ISO number (8601)).

ENVIRONMENT VARIABLES
       The  following environment variables may be used to change the behavior
       of "rrdtool fetch":

       RRDCACHED_ADDRESS
           If this environment variable is set it will have the same effect as
           specifying the "--daemon" option on the command line. If  both  are
           present, the command line argument takes precedence.

AUTHOR
       Tobias Oetiker <tobi@oetiker.ch>

1.10.2                            2026-05-19                       RRDFETCH(1)
