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FSTAT(1) NetBSD General Commands Manual FSTAT(1)
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fstat -- display status of open files
fstat [-fnv] [-M core] [-N system] [-p pid] [-u user] [file ...]
fstat identifies open files. A file is considered open by a process if
it was explicitly opened, is the working directory, root directory,
active pure text, or kernel trace file for that process. If no options
are specified, fstat reports on all open files in the system.
-f Restrict examination to files open in the same filesystems as the
named file arguments, or to the filesystem containing the current
directory if there are no additional filename arguments. For
example, to find all files open in the filesystem where the
directory /usr/src resides, type ``fstat -f /usr/src''.
-M Extract values associated with the name list from the specified
core instead of the default /dev/kmem.
-N Extract the name list from the specified system instead of the
-n Numerical format. Print the device number (maj,min) of the
filesystem the file resides in rather than the mount point name;
for special files, print the device number that the special
device refers to rather than the filename in /dev; and print the
mode of the file in octal instead of symbolic form.
-p Report all files open by the specified process.
-u Report all files open by the specified user.
-v Verbose mode. Print error messages upon failures to locate par-
ticular system data structures rather than silently ignoring
them. Most of these data structures are dynamically created or
deleted and it is possible for them to disappear while fstat is
running. This is normal and unavoidable since the rest of the
system is running while fstat itself is running.
Restrict reports to the specified files.
The following fields are printed:
USER The username of the owner of the process (effective UID).
CMD The command name of the process.
PID The process ID.
FD The file number in the per-process open file table or one of the
following special names:
text pure text inode
wd current working directory
root root inode
tr kernel trace file
If the file number is followed by an asterisk (``*''), the file is
not an inode, but rather a socket, FIFO, or there is an error. In
this case the remainder of the line doesn't correspond to the
remaining headers -- the format of the line is described later
MOUNT If the -n flag wasn't specified, this header is present and is the
pathname that the filesystem the file resides in is mounted on.
DEV If the -n flag is specified, this header is present and is the
major/minor number of the device that this file resides in.
INUM The inode number of the file.
MODE The mode of the file. If the -n flag isn't specified, the mode is
printed using a symbolic format (see strmode(3)); otherwise, the
mode is printed as an octal number.
SZ|DV If the file is not a character or block special file, prints the
size of the file in bytes. Otherwise, if the -n flag is not spec-
ified, prints the name of the special file as located in /dev. If
that cannot be located, or the -n flag is specified, prints the
major/minor device number that the special device refers to.
R/W This column describes the access mode that the file allows. The
letter ``r'' indicates open for reading; the letter ``w'' indi-
cates open for writing. This field is useful when trying to find
the processes that are preventing a filesystem from being down-
graded to read-only.
NAME If filename arguments are specified and the -f flag is not, then
this field is present and is the name associated with the given
file. Normally the name cannot be determined since there is no
mapping from an open file back to the directory entry that was
used to open that file. Also, since different directory entries
may reference the same file (via ln(1)), the name printed may not
be the actual name that the process originally used to open that
The formatting of open sockets depends on the protocol domain. In all
cases the first field is the domain name, the second field is the socket
type (stream, dgram, etc), and the third is the socket flags field (in
hex). The remaining fields are protocol dependent. For TCP, it is the
address of the tcpcb, and for UDP, the inpcb (socket pcb). For UNIX
domain sockets, its the address of the socket pcb and the address of the
connected pcb (if connected). Otherwise the protocol number and address
of the socket itself are printed. The attempt is to make enough informa-
tion available to permit further analysis without duplicating netstat(1).
For example, the addresses mentioned above are the addresses which the
``netstat -A'' command would print for TCP, UDP, and UNIX domain. Note
that since pipes are implemented using sockets, a pipe appears as a con-
nected UNIX domain stream socket. A unidirectional UNIX domain socket
indicates the direction of flow with an arrow (``<-'' or ``->''), and a
full duplex socket shows a double arrow (``<->'').
For internet sockets fstat also attempts to print the internet address
and port for the local end of a connection. If the socket is connected,
it also prints the remote internet address and port. An asterisk (``*'')
is used to indicate an INADDR_ANY binding.
netstat(1), nfsstat(1), ps(1), sockstat(1), systat(1), vmstat(1),
The fstat command appeared in 4.3BSD-Tahoe.
Since fstat takes a snapshot of the system, it is only correct for a very
short period of time.
Moreover, because DNS resolution and YP lookups cause many file descrip-
tor changes, fstat does not attempt to translate the internet address and
port numbers into symbolic names.
NetBSD 5.0 February 18, 1999 NetBSD 5.0