Provided by: sysstat_11.6.1-1ubuntu0.2_amd64 bug

NAME

       sar - Collect, report, or save system activity information.

SYNOPSIS

       sar [ -A ] [ -B ] [ -b ] [ -C ] [ -D ] [ -d ] [ -F [ MOUNT ] ] [ -H ] [ -h ] [ -p ] [ -q ] [ -r [ ALL ] ]
       [ -S ] [ -t ] [ -u [ ALL ] ] [ -V ] [ -v ] [ -W ] [ -w ] [ -y ] [ --human ] [ --sadc ] [ -I { int_list  |
       SUM | ALL } ] [ -P { cpu_list | ALL } ] [ -m { keyword [,...] | ALL } ] [ -n { keyword [,...] | ALL } ] [
       -j { ID | LABEL | PATH | UUID | ... } ] [ -f [ filename ] | -o [ filename ] | -[0-9]+ ] [ -i interval ] [
       -s [ hh:mm[:ss] ] ] [ -e [ hh:mm[:ss] ] ] [ interval [ count ] ]

DESCRIPTION

       The  sar  command  writes to standard output the contents of selected cumulative activity counters in the
       operating system. The accounting system, based on the values in the count and interval parameters, writes
       information  the specified number of times spaced at the specified intervals in seconds.  If the interval
       parameter is set to zero, the sar command displays the average statistics for the time since  the  system
       was  started.  If  the  interval  parameter  is  specified  without the count parameter, then reports are
       generated continuously.  The collected data can also be saved in the file specified by  the  -o  filename
       flag,  in  addition  to  being  displayed  onto the screen. If filename is omitted, sar uses the standard
       system activity daily data file (see below).  By default all the data available from the kernel are saved
       in the data file.

       The  sar command extracts and writes to standard output records previously saved in a file. This file can
       be either the one specified by the -f flag or, by default, the standard system activity daily data  file.
       It  is  also  possible  to  enter -1, -2 etc. as an argument to sar to display data of that days ago. For
       example, -1 will point at the standard system activity file of yesterday.

       Standard system activity daily data files are named saDD or saYYYYMMDD, where YYYY stands for the current
       year,  MM  for  the current month and DD for the current day. They are the default files used by sar only
       when no filename has been explicitly specified.  When used to write data to files (with its  option  -o),
       sar  will  use  saYYYYMMDD  if  option  -D  has also been specified, else it will use saDD.  When used to
       display the records previously saved in a file, sar will look for the most recent of saDD and saYYYYMMDD,
       and use it.

       Standard  system  activity daily data files are located in the /var/log/sysstat directory by default. Yet
       it is possible to specify an alternate location for them: If a directory (instead of  a  plain  file)  is
       used with options -f or -o then it will be considered as the directory containing the data files.

       Without  the -P flag, the sar command reports system-wide (global among all processors) statistics, which
       are calculated as averages for values expressed as percentages, and as sums otherwise. If the -P flag  is
       given, the sar command reports activity which relates to the specified processor or processors. If -P ALL
       is given, the sar command reports statistics for each individual processor and  global  statistics  among
       all processors.

       You can select information about specific system activities using flags. Not specifying any flags selects
       only CPU activity.  Specifying the -A flag selects all possible activities.

       The default version of the sar command (CPU utilization report) might be one of the first facilities  the
       user  runs  to  begin  system  activity investigation, because it monitors major system resources. If CPU
       utilization is near 100 percent (user + nice + system), the workload sampled is CPU-bound.

       If multiple samples and multiple reports are desired, it is convenient to specify an output file for  the
       sar command.  Run the sar command as a background process. The syntax for this is:

       sar -o datafile interval count >/dev/null 2>&1 &

       All  data  are  captured in binary form and saved to a file (datafile).  The data can then be selectively
       displayed with the sar command using the -f option. Set the interval and count parameters to select count
       records  at  interval  second  intervals. If the count parameter is not set, all the records saved in the
       file will be selected.  Collection of data in this manner is useful to characterize system usage  over  a
       period of time and determine peak usage hours.

       Note:     The sar command only reports on local activities.

OPTIONS

       -A     This is equivalent to specifying -bBdFHqSuvwWy -I SUM -I ALL -m ALL -n ALL -r ALL -u ALL -P ALL.

       -B     Report paging statistics.  The following values are displayed:

              pgpgin/s
                     Total number of kilobytes the system paged in from disk per second.

              pgpgout/s
                     Total number of kilobytes the system paged out to disk per second.

              fault/s
                     Number  of  page faults (major + minor) made by the system per second.  This is not a count
                     of page faults that generate I/O, because some page faults can be resolved without I/O.

              majflt/s
                     Number of major faults the system has made per second, those which have required loading  a
                     memory page from disk.

              pgfree/s
                     Number of pages placed on the free list by the system per second.

              pgscank/s
                     Number of pages scanned by the kswapd daemon per second.

              pgscand/s
                     Number of pages scanned directly per second.

              pgsteal/s
                     Number of pages the system has reclaimed from cache (pagecache and swapcache) per second to
                     satisfy its memory demands.

              %vmeff
                     Calculated as pgsteal / pgscan, this is a metric of the efficiency of page reclaim.  If  it
                     is  near  100%  then  almost  every  page coming off the tail of the inactive list is being
                     reaped. If it gets too low (e.g. less than 30%) then the  virtual  memory  is  having  some
                     difficulty.   This  field  is  displayed  as  zero if no pages have been scanned during the
                     interval of time.

       -b     Report I/O and transfer rate statistics.  The following values are displayed:

              tps
                     Total number of transfers per second that were issued to physical devices.  A  transfer  is
                     an  I/O  request  to  a  physical  device. Multiple logical requests can be combined into a
                     single I/O request to the device.  A transfer is of indeterminate size.

              rtps
                     Total number of read requests per second issued to physical devices.

              wtps
                     Total number of write requests per second issued to physical devices.

              bread/s
                     Total amount of data read from the devices in blocks per second.  Blocks are equivalent  to
                     sectors and therefore have a size of 512 bytes.

              bwrtn/s
                     Total amount of data written to devices in blocks per second.

       -C     When reading data from a file, tell sar to display comments that have been inserted by sadc.

       -D     Use  saYYYYMMDD  instead of saDD as the standard system activity daily data file name. This option
              works only when used in conjunction with option -o to save data to file.

       -d     Report activity for each block device.  When data are displayed, the device  specification  devM-n
              is  generally  used  (DEV  column).   M  is the major number of the device and n its minor number.
              Device names may also be pretty-printed if option -p is used or persistent  device  names  can  be
              printed if option -j is used (see below).  Note that disk activity depends on sadc options -S DISK
              and -S XDISK to be collected. The following values are displayed:

              tps
                     Total number of transfers per second that were issued to physical devices.  A  transfer  is
                     an  I/O  request  to  a  physical  device. Multiple logical requests can be combined into a
                     single I/O request to the device.  A transfer is of indeterminate size.

              rkB/s
                     Number of kilobytes read from the device per second.

              wkB/s
                     Number of kilobytes written to the device per second.

              areq-sz
                     The average size (in kilobytes) of the I/O requests that were issued to the device.
                     Note: In previous versions, this field was known as avgrq-sz and was expressed in sectors.

              aqu-sz
                     The average queue length of the requests that were issued to the device.
                     Note: In previous versions, this field was known as avgqu-sz.

              await
                     The average time (in milliseconds) for I/O requests issued to the device to be served. This
                     includes the time spent by the requests in queue and the time spent servicing them.

              svctm
                     The average service time (in milliseconds) for I/O requests that were issued to the device.
                     Warning! Do not trust this field any more. This field will be removed in a  future  sysstat
                     version.

              %util
                     Percentage  of  elapsed time during which I/O requests were issued to the device (bandwidth
                     utilization for the device). Device saturation occurs when this value is close to 100%  for
                     devices  serving  requests  serially. But for devices serving requests in parallel, such as
                     RAID arrays and modern SSDs, this number does not reflect their performance limits.

       -e [ hh:mm[:ss] ]
              Set the ending time of the report. The default ending time is 18:00:00. Hours  must  be  given  in
              24-hour  format.  This option can be used when data are read from or written to a file (options -f
              or -o).

       -F [ MOUNT ]
              Display statistics for currently mounted filesystems. Pseudo-filesystems are ignored. At  the  end
              of  the  report,  sar will display a summary of all those filesystems.  Use of the MOUNT parameter
              keyword indicates that mountpoint will be  reported  instead  of  filesystem  device.   Note  that
              filesystems statistics depend on sadc option -S XDISK to be collected.

              The following values are displayed:

              MBfsfree
                     Total amount a free space in megabytes (including space available only to privileged user).

              MBfsused
                     Total amount of space used in megabytes.

              %fsused
                     Percentage of filesystem space used, as seen by a privileged user.

              %ufsused
                     Percentage of filesystem space used, as seen by an unprivileged user.

              Ifree
                     Total number of free file nodes in filesystem.

              Iused
                     Total number of file nodes used in filesystem.

              %Iused
                     Percentage of file nodes used in filesystem.

       -f [ filename ]
              Extract records from filename (created by the -o filename flag). The default value of the filename
              parameter is the current standard system activity daily data file.  If  filename  is  a  directory
              instead  of a plain file then it is considered as the directory where the standard system activity
              daily data files are located. The -f option is exclusive of the -o option.

       -H     Report hugepages utilization statistics.  The following values are displayed:

              kbhugfree
                     Amount of hugepages memory in kilobytes that is not yet allocated.

              kbhugused
                     Amount of hugepages memory in kilobytes that has been allocated.

              %hugused
                     Percentage of total hugepages memory that has been allocated.

       -h     Display a short help message then exit.

       --human
              Print sizes in human readable format (e.g. 1k, 1.23M, etc.)  The units displayed with this  option
              supersede any other default units (e.g.  kilobytes, sectors...) associated with the metrics.

       -I { int_list | SUM | ALL }
              Report statistics for interrupts.  int_list is a list of comma-separated values or range of values
              (e.g., 0-16,35,400-).  The SUM keyword indicates that the total number of interrupts received  per
              second  is  to  be  displayed.  The  ALL  keyword  indicates  that statistics from all interrupts,
              including potential APIC interrupt sources, are to be reported.  Note  that  interrupt  statistics
              depend on sadc option "-S INT" to be collected.

       -i interval
              Select  data  records  at  seconds  as  close  as possible to the number specified by the interval
              parameter.

       -j { ID | LABEL | PATH | UUID | ... }
              Display persistent device names. Use this option in  conjunction  with  option  -d.   Options  ID,
              LABEL,  etc.  specify  the  type  of  the  persistent  name.  These  options are not limited, only
              prerequisite is that directory with  required  persistent  names  is  present  in  /dev/disk.   If
              persistent  name  is  not  found  for the device, the device name is pretty-printed (see option -p
              below).

       -m { keyword [,...] | ALL }
              Report power management statistics.  Note that these statistics depend on sadc's option "-S POWER"
              to be collected.

              Possible keywords are CPU, FAN, FREQ, IN, TEMP and USB.

              With the CPU keyword, statistics about CPU are reported.  The following value is displayed:

              MHz
                     Instantaneous CPU clock frequency in MHz.

              With  the  FAN  keyword,  statistics  about  fans  speed  are  reported.  The following values are
              displayed:

              rpm
                     Fan speed expressed in revolutions per minute.

              drpm
                     This field is calculated as the difference between current fan  speed  (rpm)  and  its  low
                     limit (fan_min).

              DEVICE
                     Sensor device name.

              With  the FREQ keyword, statistics about CPU clock frequency are reported.  The following value is
              displayed:

              wghMHz
                     Weighted average CPU clock frequency in MHz.  Note that the cpufreq-stats  driver  must  be
                     compiled in the kernel for this option to work.

              With  the  IN  keyword,  statistics  about  voltage inputs are reported.  The following values are
              displayed:

              inV
                     Voltage input expressed in Volts.

              %in
                     Relative input value. A value of 100% means that voltage input has reached its  high  limit
                     (in_max) whereas a value of 0% means that it has reached its low limit (in_min).

              DEVICE
                     Sensor device name.

              With  the  TEMP  keyword, statistics about devices temperature are reported.  The following values
              are displayed:

              degC
                     Device temperature expressed in degrees Celsius.

              %temp
                     Relative device temperature. A value of 100% means that temperature has  reached  its  high
                     limit (temp_max).

              DEVICE
                     Sensor device name.

              With  the  USB  keyword, the sar command takes a snapshot of all the USB devices currently plugged
              into the system. At the end of the report, sar will display a summary of all  those  USB  devices.
              The following values are displayed:

              BUS
                     Root hub number of the USB device.

              idvendor
                     Vendor ID number (assigned by USB organization).

              idprod
                     Product ID number (assigned by Manufacturer).

              maxpower
                     Maximum power consumption of the device (expressed in mA).

              manufact
                     Manufacturer name.

              product
                     Product name.

              The  ALL  keyword  is  equivalent to specifying all the keywords above and therefore all the power
              management statistics are reported.

       -n { keyword [,...] | ALL }
              Report network statistics.

              Possible keywords are DEV, EDEV, FC, ICMP, EICMP, ICMP6, EICMP6, IP, EIP, IP6,  EIP6,  NFS,  NFSD,
              SOCK, SOCK6, SOFT, TCP, ETCP, UDP and UDP6.

              With  the DEV keyword, statistics from the network devices are reported.  The following values are
              displayed:

              IFACE
                     Name of the network interface for which statistics are reported.

              rxpck/s
                     Total number of packets received per second.

              txpck/s
                     Total number of packets transmitted per second.

              rxkB/s
                     Total number of kilobytes received per second.

              txkB/s
                     Total number of kilobytes transmitted per second.

              rxcmp/s
                     Number of compressed packets received per second (for cslip etc.).

              txcmp/s
                     Number of compressed packets transmitted per second.

              rxmcst/s
                     Number of multicast packets received per second.

              %ifutil
                     Utilization percentage of the network interface. For half-duplex interfaces, utilization is
                     calculated  using  the sum of rxkB/s and txkB/s as a percentage of the interface speed. For
                     full-duplex, this is the greater of rxkB/S or txkB/s.

              With the EDEV keyword, statistics on failures (errors) from the network devices are reported.  The
              following values are displayed:

              IFACE
                     Name of the network interface for which statistics are reported.

              rxerr/s
                     Total number of bad packets received per second.

              txerr/s
                     Total number of errors that happened per second while transmitting packets.

              coll/s
                     Number of collisions that happened per second while transmitting packets.

              rxdrop/s
                     Number of received packets dropped per second because of a lack of space in linux buffers.

              txdrop/s
                     Number  of  transmitted  packets  dropped  per  second  because of a lack of space in linux
                     buffers.

              txcarr/s
                     Number of carrier-errors that happened per second while transmitting packets.

              rxfram/s
                     Number of frame alignment errors that happened per second on received packets.

              rxfifo/s
                     Number of FIFO overrun errors that happened per second on received packets.

              txfifo/s
                     Number of FIFO overrun errors that happened per second on transmitted packets.

              With the FC keyword, statistics about fibre channel traffic are reported.  Note that fibre channel
              statistics depend on sadc's option "-S DISK" to be collected.  The following values are displayed:

              FCHOST
                     Name  of  the  fibre  channel  host  bus  adapter  (HBA) interface for which statistics are
                     reported.

              fch_rxf/s
                     The total number of frames received per second.

              fch_txf/s
                     The total number of frames transmitted per second.

              fch_rxw/s
                     The total number of transmission words received per second.

              fch_txw/s
                     The total number of transmission words transmitted per second.

              With the ICMP keyword, statistics about ICMPv4 network traffic are  reported.   Note  that  ICMPv4
              statistics  depend on sadc's option "-S SNMP" to be collected.  The following values are displayed
              (formal SNMP names between square brackets):

              imsg/s
                     The total number of ICMP messages which the entity received per second [icmpInMsgs].   Note
                     that this counter includes all those counted by ierr/s.

              omsg/s
                     The  total  number  of  ICMP  messages  which  this  entity  attempted  to  send per second
                     [icmpOutMsgs].  Note that this counter includes all those counted by oerr/s.

              iech/s
                     The number of ICMP Echo (request) messages received per second [icmpInEchos].

              iechr/s
                     The number of ICMP Echo Reply messages received per second [icmpInEchoReps].

              oech/s
                     The number of ICMP Echo (request) messages sent per second [icmpOutEchos].

              oechr/s
                     The number of ICMP Echo Reply messages sent per second [icmpOutEchoReps].

              itm/s
                     The number of ICMP Timestamp (request) messages received per second [icmpInTimestamps].

              itmr/s
                     The number of ICMP Timestamp Reply messages received per second [icmpInTimestampReps].

              otm/s
                     The number of ICMP Timestamp (request) messages sent per second [icmpOutTimestamps].

              otmr/s
                     The number of ICMP Timestamp Reply messages sent per second [icmpOutTimestampReps].

              iadrmk/s
                     The number of ICMP Address Mask Request messages received per second [icmpInAddrMasks].

              iadrmkr/s
                     The number of ICMP Address Mask Reply messages received per second [icmpInAddrMaskReps].

              oadrmk/s
                     The number of ICMP Address Mask Request messages sent per second [icmpOutAddrMasks].

              oadrmkr/s
                     The number of ICMP Address Mask Reply messages sent per second [icmpOutAddrMaskReps].

              With the EICMP keyword, statistics about ICMPv4 error messages are  reported.   Note  that  ICMPv4
              statistics  depend on sadc's option "-S SNMP" to be collected.  The following values are displayed
              (formal SNMP names between square brackets):

              ierr/s
                     The number of ICMP messages per second which the entity received but determined  as  having
                     ICMP-specific errors (bad ICMP checksums, bad length, etc.) [icmpInErrors].

              oerr/s
                     The  number  of  ICMP  messages  per  second which this entity did not send due to problems
                     discovered within ICMP such as a lack of buffers [icmpOutErrors].

              idstunr/s
                     The   number   of   ICMP   Destination   Unreachable   messages   received    per    second
                     [icmpInDestUnreachs].

              odstunr/s
                     The number of ICMP Destination Unreachable messages sent per second [icmpOutDestUnreachs].

              itmex/s
                     The number of ICMP Time Exceeded messages received per second [icmpInTimeExcds].

              otmex/s
                     The number of ICMP Time Exceeded messages sent per second [icmpOutTimeExcds].

              iparmpb/s
                     The number of ICMP Parameter Problem messages received per second [icmpInParmProbs].

              oparmpb/s
                     The number of ICMP Parameter Problem messages sent per second [icmpOutParmProbs].

              isrcq/s
                     The number of ICMP Source Quench messages received per second [icmpInSrcQuenchs].

              osrcq/s
                     The number of ICMP Source Quench messages sent per second [icmpOutSrcQuenchs].

              iredir/s
                     The number of ICMP Redirect messages received per second [icmpInRedirects].

              oredir/s
                     The number of ICMP Redirect messages sent per second [icmpOutRedirects].

              With  the  ICMP6  keyword, statistics about ICMPv6 network traffic are reported.  Note that ICMPv6
              statistics depend on sadc's option "-S IPV6" to be collected.  The following values are  displayed
              (formal SNMP names between square brackets):

              imsg6/s
                     The  total  number of ICMP messages received by the interface per second which includes all
                     those counted by ierr6/s [ipv6IfIcmpInMsgs].

              omsg6/s
                     The total number of ICMP messages  which  this  interface  attempted  to  send  per  second
                     [ipv6IfIcmpOutMsgs].

              iech6/s
                     The  number  of  ICMP  Echo  (request)  messages  received  by  the  interface  per  second
                     [ipv6IfIcmpInEchos].

              iechr6/s
                     The  number  of  ICMP  Echo  Reply  messages  received  by   the   interface   per   second
                     [ipv6IfIcmpInEchoReplies].

              oechr6/s
                     The   number   of   ICMP   Echo   Reply   messages   sent   by  the  interface  per  second
                     [ipv6IfIcmpOutEchoReplies].

              igmbq6/s
                     The number of ICMPv6 Group Membership Query messages received by the interface  per  second
                     [ipv6IfIcmpInGroupMembQueries].

              igmbr6/s
                     The  number  of  ICMPv6  Group  Membership  Response messages received by the interface per
                     second [ipv6IfIcmpInGroupMembResponses].

              ogmbr6/s
                     The   number   of   ICMPv6   Group   Membership   Response   messages   sent   per   second
                     [ipv6IfIcmpOutGroupMembResponses].

              igmbrd6/s
                     The  number  of  ICMPv6  Group  Membership Reduction messages received by the interface per
                     second [ipv6IfIcmpInGroupMembReductions].

              ogmbrd6/s
                     The  number   of   ICMPv6   Group   Membership   Reduction   messages   sent   per   second
                     [ipv6IfIcmpOutGroupMembReductions].

              irtsol6/s
                     The  number  of  ICMP  Router  Solicit  messages  received  by  the  interface  per  second
                     [ipv6IfIcmpInRouterSolicits].

              ortsol6/s
                     The number  of  ICMP  Router  Solicitation  messages  sent  by  the  interface  per  second
                     [ipv6IfIcmpOutRouterSolicits].

              irtad6/s
                     The  number  of  ICMP  Router  Advertisement  messages received by the interface per second
                     [ipv6IfIcmpInRouterAdvertisements].

              inbsol6/s
                     The number of  ICMP  Neighbor  Solicit  messages  received  by  the  interface  per  second
                     [ipv6IfIcmpInNeighborSolicits].

              onbsol6/s
                     The  number  of  ICMP  Neighbor  Solicitation  messages  sent  by  the interface per second
                     [ipv6IfIcmpOutNeighborSolicits].

              inbad6/s
                     The number of ICMP Neighbor Advertisement messages received by  the  interface  per  second
                     [ipv6IfIcmpInNeighborAdvertisements].

              onbad6/s
                     The  number  of  ICMP  Neighbor  Advertisement  messages  sent  by the interface per second
                     [ipv6IfIcmpOutNeighborAdvertisements].

              With the EICMP6 keyword, statistics about ICMPv6 error messages are reported.   Note  that  ICMPv6
              statistics  depend on sadc's option "-S IPV6" to be collected.  The following values are displayed
              (formal SNMP names between square brackets):

              ierr6/s
                     The number of ICMP messages per second which  the  interface  received  but  determined  as
                     having ICMP-specific errors (bad ICMP checksums, bad length, etc.)  [ipv6IfIcmpInErrors]

              idtunr6/s
                     The  number  of  ICMP Destination Unreachable messages received by the interface per second
                     [ipv6IfIcmpInDestUnreachs].

              odtunr6/s
                     The number of ICMP Destination Unreachable  messages  sent  by  the  interface  per  second
                     [ipv6IfIcmpOutDestUnreachs].

              itmex6/s
                     The   number  of  ICMP  Time  Exceeded  messages  received  by  the  interface  per  second
                     [ipv6IfIcmpInTimeExcds].

              otmex6/s
                     The  number  of  ICMP  Time  Exceeded  messages  sent   by   the   interface   per   second
                     [ipv6IfIcmpOutTimeExcds].

              iprmpb6/s
                     The  number  of  ICMP  Parameter  Problem  messages  received  by  the interface per second
                     [ipv6IfIcmpInParmProblems].

              oprmpb6/s
                     The  number  of  ICMP  Parameter  Problem  messages  sent  by  the  interface  per   second
                     [ipv6IfIcmpOutParmProblems].

              iredir6/s
                     The    number    of    Redirect   messages   received   by   the   interface   per   second
                     [ipv6IfIcmpInRedirects].

              oredir6/s
                     The number of Redirect messages sent by the interface by second [ipv6IfIcmpOutRedirects].

              ipck2b6/s
                     The number  of  ICMP  Packet  Too  Big  messages  received  by  the  interface  per  second
                     [ipv6IfIcmpInPktTooBigs].

              opck2b6/s
                     The   number   of   ICMP  Packet  Too  Big  messages  sent  by  the  interface  per  second
                     [ipv6IfIcmpOutPktTooBigs].

              With the IP keyword,  statistics  about  IPv4  network  traffic  are  reported.   Note  that  IPv4
              statistics  depend on sadc's option "-S SNMP" to be collected.  The following values are displayed
              (formal SNMP names between square brackets):

              irec/s
                     The total number of input datagrams received from interfaces per  second,  including  those
                     received in error [ipInReceives].

              fwddgm/s
                     The  number  of  input  datagrams  per second, for which this entity was not their final IP
                     destination, as a result of which an attempt was made to find a route to  forward  them  to
                     that final destination [ipForwDatagrams].

              idel/s
                     The  total number of input datagrams successfully delivered per second to IP user-protocols
                     (including ICMP) [ipInDelivers].

              orq/s
                     The total number of IP datagrams which local IP user-protocols  (including  ICMP)  supplied
                     per second to IP in requests for transmission [ipOutRequests].  Note that this counter does
                     not include any datagrams counted in fwddgm/s.

              asmrq/s
                     The number of IP fragments received per second which  needed  to  be  reassembled  at  this
                     entity [ipReasmReqds].

              asmok/s
                     The number of IP datagrams successfully re-assembled per second [ipReasmOKs].

              fragok/s
                     The number of IP datagrams that have been successfully fragmented at this entity per second
                     [ipFragOKs].

              fragcrt/s
                     The number of IP datagram fragments that have been generated per  second  as  a  result  of
                     fragmentation at this entity [ipFragCreates].

              With  the  EIP  keyword,  statistics  about  IPv4  network  errors  are  reported.  Note that IPv4
              statistics depend on sadc's option "-S SNMP" to be collected.  The following values are  displayed
              (formal SNMP names between square brackets):

              ihdrerr/s
                     The  number  of  input  datagrams  discarded  per second due to errors in their IP headers,
                     including bad  checksums,  version  number  mismatch,  other  format  errors,  time-to-live
                     exceeded, errors discovered in processing their IP options, etc. [ipInHdrErrors]

              iadrerr/s
                     The  number  of  input  datagrams  discarded  per second because the IP address in their IP
                     header's destination field was not a valid address to be  received  at  this  entity.  This
                     count  includes  invalid  addresses  (e.g.,  0.0.0.0)  and addresses of unsupported Classes
                     (e.g., Class E). For entities which are  not  IP  routers  and  therefore  do  not  forward
                     datagrams,  this  counter  includes datagrams discarded because the destination address was
                     not a local address [ipInAddrErrors].

              iukwnpr/s
                     The number of locally-addressed datagrams received successfully but  discarded  per  second
                     because of an unknown or unsupported protocol [ipInUnknownProtos].

              idisc/s
                     The  number  of  input  IP  datagrams  per second for which no problems were encountered to
                     prevent their continued processing, but which were discarded  (e.g.,  for  lack  of  buffer
                     space)  [ipInDiscards].   Note  that  this counter does not include any datagrams discarded
                     while awaiting re-assembly.

              odisc/s
                     The number of output IP datagrams per second  for  which  no  problem  was  encountered  to
                     prevent  their  transmission to their destination, but which were discarded (e.g., for lack
                     of buffer space) [ipOutDiscards].  Note that this counter would include  datagrams  counted
                     in fwddgm/s if any such packets met this (discretionary) discard criterion.

              onort/s
                     The number of IP datagrams discarded per second because no route could be found to transmit
                     them to their destination [ipOutNoRoutes].  Note that this  counter  includes  any  packets
                     counted  in  fwddgm/s  which  meet  this 'no-route' criterion.  Note that this includes any
                     datagrams which a host cannot route because all of its default routers are down.

              asmf/s
                     The number of failures detected per second by the IP re-assembly  algorithm  (for  whatever
                     reason:  timed out, errors, etc) [ipReasmFails].  Note that this is not necessarily a count
                     of discarded IP fragments since some algorithms can lose track of the number  of  fragments
                     by combining them as they are received.

              fragf/s
                     The  number  of  IP datagrams that have been discarded per second because they needed to be
                     fragmented at this entity but could not be, e.g., because their Don't Fragment flag was set
                     [ipFragFails].

              With  the  IP6  keyword,  statistics  about  IPv6  network  traffic  are reported.  Note that IPv6
              statistics depend on sadc's option "-S IPV6" to be collected.  The following values are  displayed
              (formal SNMP names between square brackets):

              irec6/s
                     The  total  number  of input datagrams received from interfaces per second, including those
                     received in error [ipv6IfStatsInReceives].

              fwddgm6/s
                     The number of output datagrams per second which this entity received and forwarded to their
                     final destinations [ipv6IfStatsOutForwDatagrams].

              idel6/s
                     The  total  number  of  datagrams  successfully delivered per second to IPv6 user-protocols
                     (including ICMP) [ipv6IfStatsInDelivers].

              orq6/s
                     The total number of  IPv6  datagrams  which  local  IPv6  user-protocols  (including  ICMP)
                     supplied  per  second  to IPv6 in requests for transmission [ipv6IfStatsOutRequests].  Note
                     that this counter does not include any datagrams counted in fwddgm6/s.

              asmrq6/s
                     The number of IPv6 fragments received per second which needed to  be  reassembled  at  this
                     interface [ipv6IfStatsReasmReqds].

              asmok6/s
                     The number of IPv6 datagrams successfully reassembled per second [ipv6IfStatsReasmOKs].

              imcpck6/s
                     The    number    of    multicast   packets   received   per   second   by   the   interface
                     [ipv6IfStatsInMcastPkts].

              omcpck6/s
                     The   number   of   multicast   packets   transmitted   per   second   by   the   interface
                     [ipv6IfStatsOutMcastPkts].

              fragok6/s
                     The  number  of  IPv6  datagrams  that  have  been  successfully  fragmented at this output
                     interface per second [ipv6IfStatsOutFragOKs].

              fragcr6/s
                     The number of output datagram fragments that have been generated per second as a result  of
                     fragmentation at this output interface [ipv6IfStatsOutFragCreates].

              With  the  EIP6  keyword,  statistics  about  IPv6  network  errors  are reported.  Note that IPv6
              statistics depend on sadc's option "-S IPV6" to be collected.  The following values are  displayed
              (formal SNMP names between square brackets):

              ihdrer6/s
                     The  number  of  input  datagrams discarded per second due to errors in their IPv6 headers,
                     including version  number  mismatch,  other  format  errors,  hop  count  exceeded,  errors
                     discovered in processing their IPv6 options, etc. [ipv6IfStatsInHdrErrors]

              iadrer6/s
                     The  number  of input datagrams discarded per second because the IPv6 address in their IPv6
                     header's destination field was not a valid address to be  received  at  this  entity.  This
                     count  includes  invalid  addresses  (e.g., ::0) and unsupported addresses (e.g., addresses
                     with unallocated prefixes). For entities which are not IPv6 routers and  therefore  do  not
                     forward  datagrams,  this  counter  includes  datagrams  discarded  because the destination
                     address was not a local address [ipv6IfStatsInAddrErrors].

              iukwnp6/s
                     The number of locally-addressed datagrams received successfully but  discarded  per  second
                     because of an unknown or unsupported protocol [ipv6IfStatsInUnknownProtos].

              i2big6/s
                     The  number  of  input  datagrams that could not be forwarded per second because their size
                     exceeded the link MTU of outgoing interface [ipv6IfStatsInTooBigErrors].

              idisc6/s
                     The number of input IPv6 datagrams per second for which no  problems  were  encountered  to
                     prevent  their  continued  processing,  but  which were discarded (e.g., for lack of buffer
                     space) [ipv6IfStatsInDiscards]. Note that this  counter  does  not  include  any  datagrams
                     discarded while awaiting re-assembly.

              odisc6/s
                     The  number  of  output  IPv6  datagrams per second for which no problem was encountered to
                     prevent their transmission to their destination, but which were discarded (e.g.,  for  lack
                     of  buffer  space) [ipv6IfStatsOutDiscards]. Note that this counter would include datagrams
                     counted in fwddgm6/s if any such packets met this (discretionary) discard criterion.

              inort6/s
                     The number of input datagrams discarded per second because  no  route  could  be  found  to
                     transmit them to their destination [ipv6IfStatsInNoRoutes].

              onort6/s
                     The number of locally generated IP datagrams discarded per second because no route could be
                     found to transmit them to their destination [unknown formal SNMP name].

              asmf6/s
                     The number of failures detected per second by the IPv6 re-assembly algorithm (for  whatever
                     reason:   timed  out,  errors,  etc.)  [ipv6IfStatsReasmFails].   Note  that  this  is  not
                     necessarily a count of discarded IPv6 fragments since some algorithms can lose track of the
                     number of fragments by combining them as they are received.

              fragf6/s
                     The  number of IPv6 datagrams that have been discarded per second because they needed to be
                     fragmented at this output interface but could not be [ipv6IfStatsOutFragFails].

              itrpck6/s
                     The number of input datagrams discarded per second  because  datagram  frame  didn't  carry
                     enough data [ipv6IfStatsInTruncatedPkts].

              With the NFS keyword, statistics about NFS client activity are reported.  The following values are
              displayed:

              call/s
                     Number of RPC requests made per second.

              retrans/s
                     Number of RPC requests per second, those which needed  to  be  retransmitted  (for  example
                     because of a server timeout).

              read/s
                     Number of 'read' RPC calls made per second.

              write/s
                     Number of 'write' RPC calls made per second.

              access/s
                     Number of 'access' RPC calls made per second.

              getatt/s
                     Number of 'getattr' RPC calls made per second.

              With  the  NFSD  keyword, statistics about NFS server activity are reported.  The following values
              are displayed:

              scall/s
                     Number of RPC requests received per second.

              badcall/s
                     Number of bad RPC requests received per second, those whose processing generated an error.

              packet/s
                     Number of network packets received per second.

              udp/s
                     Number of UDP packets received per second.

              tcp/s
                     Number of TCP packets received per second.

              hit/s
                     Number of reply cache hits per second.

              miss/s
                     Number of reply cache misses per second.

              sread/s
                     Number of 'read' RPC calls received per second.

              swrite/s
                     Number of 'write' RPC calls received per second.

              saccess/s
                     Number of 'access' RPC calls received per second.

              sgetatt/s
                     Number of 'getattr' RPC calls received per second.

              With the SOCK keyword, statistics on sockets in use are reported (IPv4).  The following values are
              displayed:

              totsck
                     Total number of sockets used by the system.

              tcpsck
                     Number of TCP sockets currently in use.

              udpsck
                     Number of UDP sockets currently in use.

              rawsck
                     Number of RAW sockets currently in use.

              ip-frag
                     Number of IP fragments currently in queue.

              tcp-tw
                     Number of TCP sockets in TIME_WAIT state.

              With  the  SOCK6  keyword,  statistics  on  sockets  in  use  are reported (IPv6).  Note that IPv6
              statistics depend on sadc's option "-S IPV6" to be collected.  The following values are displayed:

              tcp6sck
                     Number of TCPv6 sockets currently in use.

              udp6sck
                     Number of UDPv6 sockets currently in use.

              raw6sck
                     Number of RAWv6 sockets currently in use.

              ip6-frag
                     Number of IPv6 fragments currently in use.

              With the SOFT keyword, statistics about  software-based  network  processing  are  reported.   The
              following values are displayed:

              total/s
                     The total number of network frames processed per second.

              dropd/s
                     The  total  number  of  network  frames dropped per second because there was no room on the
                     processing queue.

              squeezd/s
                     The number of times the softirq handler function terminated per second because  its  budget
                     was consumed or the time limit was reached, but more work could have been done.

              rx_rps/s
                     The  number  of  times  the  CPU  has  been  woken  up per second to process packets via an
                     inter-processor interrupt.

              flw_lim/s
                     The number of times the flow limit has been  reached  per  second.   Flow  limiting  is  an
                     optional  RPS feature that can be used to limit the number of packets queued to the backlog
                     for each flow to a certain amount.  This can help ensure that smaller flows  are  processed
                     even though much larger flows are pushing packets in.

              With  the  TCP  keyword,  statistics  about  TCPv4  network traffic are reported.  Note that TCPv4
              statistics depend on sadc's option "-S SNMP" to be collected.  The following values are  displayed
              (formal SNMP names between square brackets):

              active/s
                     The  number  of  times  TCP connections have made a direct transition to the SYN-SENT state
                     from the CLOSED state per second [tcpActiveOpens].

              passive/s
                     The number of times TCP connections have made a direct transition  to  the  SYN-RCVD  state
                     from the LISTEN state per second [tcpPassiveOpens].

              iseg/s
                     The  total  number  of  segments  received  per  second,  including those received in error
                     [tcpInSegs].  This count includes segments received on currently established connections.

              oseg/s
                     The total number of segments sent per second, including those on  current  connections  but
                     excluding those containing only retransmitted octets [tcpOutSegs].

              With  the  ETCP  keyword,  statistics  about  TCPv4  network errors are reported.  Note that TCPv4
              statistics depend on sadc's option "-S SNMP" to be collected.  The following values are  displayed
              (formal SNMP names between square brackets):

              atmptf/s
                     The  number of times per second TCP connections have made a direct transition to the CLOSED
                     state from either the SYN-SENT state or the SYN-RCVD state, plus the number  of  times  per
                     second  TCP connections have made a direct transition to the LISTEN state from the SYN-RCVD
                     state [tcpAttemptFails].

              estres/s
                     The number of times per second TCP connections have made a direct transition to the  CLOSED
                     state from either the ESTABLISHED state or the CLOSE-WAIT state [tcpEstabResets].

              retrans/s
                     The total number of segments retransmitted per second - that is, the number of TCP segments
                     transmitted containing one or more previously transmitted octets [tcpRetransSegs].

              isegerr/s
                     The total number of segments received  in  error  (e.g.,  bad  TCP  checksums)  per  second
                     [tcpInErrs].

              orsts/s
                     The number of TCP segments sent per second containing the RST flag [tcpOutRsts].

              With  the  UDP  keyword,  statistics  about  UDPv4  network traffic are reported.  Note that UDPv4
              statistics depend on sadc's option "-S SNMP" to be collected.  The following values are  displayed
              (formal SNMP names between square brackets):

              idgm/s
                     The total number of UDP datagrams delivered per second to UDP users [udpInDatagrams].

              odgm/s
                     The total number of UDP datagrams sent per second from this entity [udpOutDatagrams].

              noport/s
                     The total number of received UDP datagrams per second for which there was no application at
                     the destination port [udpNoPorts].

              idgmerr/s
                     The number of received UDP datagrams per second that could not  be  delivered  for  reasons
                     other than the lack of an application at the destination port [udpInErrors].

              With  the  UDP6  keyword,  statistics  about  UDPv6 network traffic are reported.  Note that UDPv6
              statistics depend on sadc's option "-S IPV6" to be collected.  The following values are  displayed
              (formal SNMP names between square brackets):

              idgm6/s
                     The total number of UDP datagrams delivered per second to UDP users [udpInDatagrams].

              odgm6/s
                     The total number of UDP datagrams sent per second from this entity [udpOutDatagrams].

              noport6/s
                     The total number of received UDP datagrams per second for which there was no application at
                     the destination port [udpNoPorts].

              idgmer6/s
                     The number of received UDP datagrams per second that could not  be  delivered  for  reasons
                     other than the lack of an application at the destination port [udpInErrors].

              The  ALL  keyword is equivalent to specifying all the keywords above and therefore all the network
              activities are reported.

       -o [ filename ]
              Save the readings in the file in binary form. Each reading is in a separate  record.  The  default
              value  of  the  filename  parameter  is  the current standard system activity daily data file.  If
              filename is a directory instead of a plain file then it is considered as the directory  where  the
              standard  system  activity  daily  data  files  are located.  The -o option is exclusive of the -f
              option.  All the data available from the kernel are saved in the file (in fact, sar calls its data
              collector sadc with the option "-S ALL".  See sadc(8) manual page).

       -P { cpu_list | ALL }
              Report  per-processor statistics for the specified processor or processors.  cpu_list is a list of
              comma-separated values or range of values (e.g., 0,2,4-7,12-).  Note that processor 0 is the first
              processor,  and  processor  all  is  the  global average among all processors.  Specifying the ALL
              keyword reports statistics for each individual processor, and globally for all processors.

       -p     Pretty-print device names. Use this option in conjunction with option -d.  By  default  names  are
              printed  as  devM-n  where  M  and  n are the major and minor numbers for the device.  Use of this
              option displays the names of the devices as they  (should)  appear  in  /dev.  Name  mappings  are
              controlled by /etc/sysstat/sysstat.ioconf.

       -q     Report queue length and load averages. The following values are displayed:

              runq-sz
                     Run queue length (number of tasks waiting for run time).

              plist-sz
                     Number of tasks in the task list.

              ldavg-1
                     System  load  average  for  the last minute.  The load average is calculated as the average
                     number of runnable or running tasks (R state), and the number of tasks  in  uninterruptible
                     sleep (D state) over the specified interval.

              ldavg-5
                     System load average for the past 5 minutes.

              ldavg-15
                     System load average for the past 15 minutes.

              blocked
                     Number of tasks currently blocked, waiting for I/O to complete.

       -r [ ALL ]
              Report  memory utilization statistics. The ALL keyword indicates that all the memory fields should
              be displayed.  The following values may be displayed:

              kbmemfree
                     Amount of free memory available in kilobytes.

              kbavail
                     Estimate of how much memory in  kilobytes  is  available  for  starting  new  applications,
                     without swapping.  The estimate takes into account that the system needs some page cache to
                     function well, and that not all reclaimable slab will be reclaimable, due to items being in
                     use. The impact of those factors will vary from system to system.

              kbmemused
                     Amount  of  used  memory  in  kilobytes. This does not take into account memory used by the
                     kernel itself.

              %memused
                     Percentage of used memory.

              kbbuffers
                     Amount of memory used as buffers by the kernel in kilobytes.

              kbcached
                     Amount of memory used to cache data by the kernel in kilobytes.

              kbcommit
                     Amount of memory in kilobytes needed for current workload. This is an estimate of how  much
                     RAM/swap is needed to guarantee that there never is out of memory.

              %commit
                     Percentage  of memory needed for current workload in relation to the total amount of memory
                     (RAM+swap).  This number may be greater than 100% because the  kernel  usually  overcommits
                     memory.

              kbactive
                     Amount  of  active memory in kilobytes (memory that has been used more recently and usually
                     not reclaimed unless absolutely necessary).

              kbinact
                     Amount of inactive memory in kilobytes (memory which has been less  recently  used.  It  is
                     more eligible to be reclaimed for other purposes).

              kbdirty
                     Amount of memory in kilobytes waiting to get written back to the disk.

              kbanonpg
                     Amount of non-file backed pages in kilobytes mapped into userspace page tables.

              kbslab
                     Amount of memory in kilobytes used by the kernel to cache data structures for its own use.

              kbkstack
                     Amount of memory in kilobytes used for kernel stack space.

              kbpgtbl
                     Amount of memory in kilobytes dedicated to the lowest level of page tables.

              kbvmused
                     Amount of memory in kilobytes of used virtual address space.

       -S     Report swap space utilization statistics.  The following values are displayed:

              kbswpfree
                     Amount of free swap space in kilobytes.

              kbswpused
                     Amount of used swap space in kilobytes.

              %swpused
                     Percentage of used swap space.

              kbswpcad
                     Amount  of  cached  swap memory in kilobytes.  This is memory that once was swapped out, is
                     swapped back in but still also is in the swap area (if memory is needed it doesn't need  to
                     be swapped out again because it is already in the swap area. This saves I/O).

              %swpcad
                     Percentage of cached swap memory in relation to the amount of used swap space.

       -s [ hh:mm[:ss] ]
              Set  the  starting time of the data, causing the sar command to extract records time-tagged at, or
              following, the time specified. The default starting time is 08:00:00.   Hours  must  be  given  in
              24-hour format. This option can be used only when data are read from a file (option -f).

       --sadc Indicate  which  data  collector  is  called by sar.  If the data collector is sought in PATH then
              enter "which sadc" to know where it is located.

       -t     When reading data from a daily data file, indicate that sar should display the timestamps  in  the
              original  local  time  of the data file creator. Without this option, the sar command displays the
              timestamps in the user's locale time.

       -u [ ALL ]
              Report CPU utilization. The ALL keyword indicates that all the CPU  fields  should  be  displayed.
              The report may show the following fields:

              %user
                     Percentage   of   CPU   utilization  that  occurred  while  executing  at  the  user  level
                     (application). Note that this field includes time spent running virtual processors.

              %usr
                     Percentage  of  CPU  utilization  that  occurred  while  executing  at   the   user   level
                     (application). Note that this field does NOT include time spent running virtual processors.

              %nice
                     Percentage  of  CPU  utilization  that occurred while executing at the user level with nice
                     priority.

              %system
                     Percentage of CPU utilization that occurred while executing at the system  level  (kernel).
                     Note that this field includes time spent servicing hardware and software interrupts.

              %sys
                     Percentage  of  CPU utilization that occurred while executing at the system level (kernel).
                     Note that this field does NOT include time spent servicing hardware or software interrupts.

              %iowait
                     Percentage of time that the  CPU  or  CPUs  were  idle  during  which  the  system  had  an
                     outstanding disk I/O request.

              %steal
                     Percentage  of  time  spent  in  involuntary  wait  by  the  virtual  CPU or CPUs while the
                     hypervisor was servicing another virtual processor.

              %irq
                     Percentage of time spent by the CPU or CPUs to service hardware interrupts.

              %soft
                     Percentage of time spent by the CPU or CPUs to service software interrupts.

              %guest
                     Percentage of time spent by the CPU or CPUs to run a virtual processor.

              %gnice
                     Percentage of time spent by the CPU or CPUs to run a niced guest.

              %idle
                     Percentage of time that the CPU  or  CPUs  were  idle  and  the  system  did  not  have  an
                     outstanding disk I/O request.

              Note: On SMP machines a processor that does not have any activity at all (0.00 for every field) is
              a disabled (offline) processor.

       -V     Print version number then exit.

       -v     Report status of inode, file and other kernel tables.  The following values are displayed:

              dentunusd
                     Number of unused cache entries in the directory cache.

              file-nr
                     Number of file handles used by the system.

              inode-nr
                     Number of inode handlers used by the system.

              pty-nr
                     Number of pseudo-terminals used by the system.

       -W     Report swapping statistics. The following values are displayed:

              pswpin/s
                     Total number of swap pages the system brought in per second.

              pswpout/s
                     Total number of swap pages the system brought out per second.

       -w     Report task creation and system switching activity.

              proc/s
                     Total number of tasks created per second.

              cswch/s
                     Total number of context switches per second.

       -y     Report TTY devices activity. The following values are displayed:

              rcvin/s
                     Number of receive interrupts per second for current serial  line.  Serial  line  number  is
                     given in the TTY column.

              xmtin/s
                     Number of transmit interrupts per second for current serial line.

              framerr/s
                     Number of frame errors per second for current serial line.

              prtyerr/s
                     Number of parity errors per second for current serial line.

              brk/s
                     Number of breaks per second for current serial line.

              ovrun/s
                     Number of overrun errors per second for current serial line.

ENVIRONMENT

       The sar command takes into account the following environment variables:

       S_COLORS
              When  this variable is set, display statistics in color on the terminal.  Possible values for this
              variable are never, always or auto (the latter is the default).

              Please note that the color (being red, yellow, or some other color) used to display a value is not
              indicative of any kind of issue simply because of the color. It only indicates different ranges of
              values.

       S_COLORS_SGR
              Specify the colors and other attributes used to display statistics on the terminal.  Its value  is
              a        colon-separated       list       of       capabilities       that       defaults       to
              C=33;22:H=31;1:I=32;22:M=35;1:N=34;1:R=31;22:Z=34;22.  Supported capabilities are:

              C=     SGR (Select Graphic Rendition) substring for comments inserted in  the  binary  daily  data
                     files.

              H=     SGR substring for percentage values greater than or equal to 75%.

              I=     SGR substring for item names or values (eg. network interfaces, CPU number...)

              M=     SGR substring for percentage values in the range from 50% to 75%.

              N=     SGR substring for non-zero statistics values.

              R=     SGR substring for restart messages.

              Z=     SGR substring for zero values.

       S_TIME_DEF_TIME
              If  this  variable  exists and its value is UTC then sar will save its data in UTC time (data will
              still be displayed in local time).  sar will also use UTC time instead of local time to  determine
              the current daily data file located in the /var/log/sysstat directory. This variable may be useful
              for servers with users located across several timezones.

       S_TIME_FORMAT
              If this variable exists and its value is ISO then the current locale will be ignored when printing
              the date in the report header.  The sar command will use the ISO 8601 format (YYYY-MM-DD) instead.
              The timestamp will also be compliant with ISO 8601 format.

EXAMPLES

       sar -u 2 5
              Report CPU utilization for each 2 seconds. 5 lines are displayed.

       sar -I 14 -o int14.file 2 10
              Report statistics on IRQ 14 for each 2 seconds. 10 lines are displayed.  Data are stored in a file
              called int14.file.

       sar -r -n DEV -f /var/log/sysstat/sa16
              Display memory and network statistics saved in daily data file 'sa16'.

       sar -A
              Display all the statistics saved in current daily data file.

BUGS

       /proc filesystem must be mounted for the sar command to work.

       All the statistics are not necessarily available, depending on the kernel version used.  sar assumes that
       you are using at least a 2.6 kernel.

FILES

       /var/log/sysstat/saDD
       /var/log/sysstat/saYYYYMMDD
              The standard system activity daily data files and their default location.   YYYY  stands  for  the
              current year, MM for the current month and DD for the current day.

       /proc and /sys contain various files with system statistics.

AUTHOR

       Sebastien Godard (sysstat <at> orange.fr)

SEE ALSO

       sadc(8), sa1(8), sa2(8), sadf(1), sysstat(5), pidstat(1), mpstat(1), iostat(1), vmstat(8)

       http://pagesperso-orange.fr/sebastien.godard/