Manual Reference Pages - SADC (8)


sadc - System activity data collector.


See Also


/usr/lib/sa/sadc [ -d ] [ -F ] [ -I ] [ -L ] [ -V ] [ interval [ count ] ] [ outfile ]


The sadc command samples system data a specified number of times ( count ) at a specified interval measured in seconds ( interval ). It writes in binary format to the specified outfile or to the standard output. If outfile is set to -, then sadc uses the standard system activity daily data file, the /var/log/sa/sadd file, where the dd parameter indicates the current day. By default sadc collects all the data available from the kernel. Exceptions are interrupts and disks data, for which the relevant options must be explicitly passed to sadc (see options below).

When the count parameter is not specified, sadc writes its data endlessly. When both interval and count are not specified, a dummy record, which is used at system startup to mark the time when the counter restarts from 0, will be written. For example, one of the system startup script may write the restart mark to the daily data file by the command entry:

/usr/lib/sa/sadc -

The sadc command is intended to be used as a backend to the sar command.

Note: The sadc command only reports on local activities.


-d Tell sadc to report statistics for disks. By default sadc does not report disks activity to prevent data files from growing too large.
-F The creation of outfile will be forced. If the file already exists and has not the format expected by sadc then it will be truncated. This may be particularly useful for daily data files created by an older version of sadc and whose format is no longer compatible with current one.
-I Tell sadc to report statistics for all system interrupts. By default sadc only reports statistics for the total number of interrupts.
-L sadc will try to get an exclusive lock on the outfile before writing to it or truncating it. Failure to get the lock is fatal, except in the case of trying to write a normal (i.e. not a dummy and not a header) record to an existing file, in which case sadc will try again at the next interval. Usually, the only reason a lock would fail would be if another sadc process were also writing to the file. This can happen when cron is used to launch sadc . If the system is under heavy load, an old sadc might still be running when cron starts a new one. Without locking, this situation can result in a corrupted system activity file.
-V Print version number then exit.


The sadc command takes into account the following environment variable:

S_TIME_DEF_TIME If this variable exists and its value is UTC then sadc will save its data in UTC time. sadc will also use UTC time instead of local time to determine the current daily data file located in the /var/log/sa directory.


/usr/lib/sa/sadc 1 10 /tmp/datafile

Write 10 records of one second intervals to the /tmp/datafile binary file.


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

All the statistics are not necessarily available, depending on the kernel version used.



Indicate the daily data file, where the dd parameter is a number representing the day of the month.

/proc contains various files with system statistics.


Sebastien Godard (sysstat <at>


sar(1), sa1(8), sa2(8), sadf(1), mpstat(1), iostat(1), vmstat(8)

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