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OpenDarwin 7.2.1 - man page for fs_usage (opendarwin section 1)

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FS_USAGE(1)			   BSD General Commands Manual			      FS_USAGE(1)

NAME
     fs_usage -- report system calls and page faults related to filesystem activity in real-time

SYNOPSIS
     fs_usage [-e] [-w] [-f mode] [pid|cmd [pid|cmd] ...]

DESCRIPTION
     The fs_usage utility presents an ongoing display of system call usage information pertaining
     to filesystem activity.  It requires root privileges due to the kernel tracing facility it
     uses to operate.  By default the activity monitored includes all system processes except the
     running fs_usage process, Terminal, telnetd, sshd, rlogind, tcsh, csh and sh.  These
     defaults can be overridden such that output is limited to include or exclude a list of pro-
     cesses specified by the user.

     The output presented by fs_usage is formatted according to the size of your window.  A nar-
     row window will display fewer columns of data.  Use a wide window for maximum data display.
     You may override the window formatting restrictions by forcing a wide display with the -w
     option.  In this case, the data displayed will wrap when the window is not wide enough.

     The options are as follows:

     -e      Specifying the -e option generates output that excludes sampling of the running
	     fs_usage tool.  If a list of process ids or commands is also given, then those pro-
	     cesses are also excluded from the sampled output.

     -w      Specifying the -w option forces a wider, more detailed output, regardless of the
	     window size.

     -f      Specifying the -f option turns on output filtering based on the mode provided.  By
	     default no filtering occurs.  The supported modes are:

	     network	Only network related output is displayed.

	     filesys	Only file system related output is displayed.

     pid | cmd
	     The sampled data can be limited to a list of process ids or commands.  When a com-
	     mand name is given, all processes with that name will be sampled.	Using the -e
	     option has the opposite effect, excluding sampled data relating to the given list of
	     process ids or commands.

     If you set the DYLD_IMAGE_SUFFIX environment variable to ``_debug'', then an application
     will use the debug version of all libraries including the Carbon FileManager.  See dyld(1).
     When fs_usage is run against a Carbon Application launched in this environment, then the
     high level Carbon FileManager calls will be displayed bracketing the system calls that they
     are built on.

     The data columns displayed are as follows:

     TIMESTAMP
	     TOD when call occurred.  Wide mode will have millisecond granularity.

     CALL    The name of the network or filesystem related call, page-in, page-out or physical
	     disk access.

     FILE DESCRIPTOR
	     Of the form F=x, x is a file descriptor.  Depending on the type of system call, this
	     will be either an input value or a return value.

     BYTE COUNT
	     Of the form B=x, x is the number of bytes requested by the call.

     [ERRNO]
	     On error, the errno is displayed in brackets.

     PATHNAME
	     Pathname of the file accessed (up to the last 28 bytes).

     FAULT ADDRESS
	     Of the form A=0xnnnnnnnn, where 0xnnnnnnnn is the address being faulted.

     DISK BLOCK NUMBER
	     Of the form D=0xnnnnnnnn, where 0xnnnnnnnn is the block number of the physical disk
	     block being read or written.

     OFFSET  Of the form O=0xnnnnnnnn, where 0xnnnnnnnn is a file offset.

     SELECT RETURN
	     Of the form S=x, x is the number of ready descriptors returned by the select() sys-
	     tem call.	If S=0, the time limit expired.

     TIME INTERVAL(W)
	     The elapsed time spent in the system call.  A 'W' after the elapsed time indicates
	     the process was scheduled out during this file activity.  In this case, the elapsed
	     time includes the wait time.

     PROCESS NAME
	     The process that made the system call.

SAMPLE USAGE
     fs_usage -w -f filesys Mail

     fs_usage will display file system related data for all instances of processes named Mail.
     Maximum data output will be displayed in the window.

SEE ALSO
     top(1), sc_usage(1), latency(1), dyld(1)

Mac OS X				 November 7, 2002				 Mac OS X
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