fstat —
display
status of open files
| fstat |
[-fnosv]
[-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 executable text, or kernel trace file for that process. If
no options are specified,
fstat reports on all
open files in the system.
The options are as follows:
-
-
- -f
- Restrict examination to files open in the same file systems
as the named file arguments, or to the file system containing the current
directory if there are no additional filename arguments. For example, to
find all files open in the file system where the directory
/usr/src resides, type
# fstat -f /usr/src
-
-
- -M
core
- Extract values associated with the name list from the
specified core instead of the running kernel.
-
-
- -N
system
- Extract the name list from the specified system instead of
the running kernel.
-
-
- -n
- Numerical format. Print the device number (maj,min) of the
file system 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. Also, print
the mode of the file in octal instead of symbolic form.
-
-
- -o
- Output file offset. Follow the size field with the
descriptor's offset. Useful for checking progress as a process works
through a large file. This information is only visible to the user or
superuser.
-
-
- -p
pid
- Report all files open by the specified process.
-
-
- -s
- Report per file io statistics in two additional columns
‘XFERS’ and ‘KBYTES’. This information is only
visible to the user or superuser.
-
-
- -u
user
- Report all files open by the specified user.
-
-
- -v
- Verbose mode. Print error messages upon failures to locate
particular 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.
-
-
- file ...
- 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 - executable 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, 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 under
SOCKETS.
-
-
MOUNT- If the -n flag wasn't
specified, this header is present and is the pathname that the file system
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. It will be followed by an
asterisk (‘
*’) if the inode is
unlinked from disk.
-
-
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.
-
-
R/W- This column describes the properties of the file
descriptor:
r Open for reading
w Open for writing
e close-on-exec flag is set
This field is useful when trying to find the processes that are preventing a
file system from being downgraded to read-only.
-
-
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 specified, 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.
-
-
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
file.
-
-
XFERS- Displays number of total data transfers performed on the
file.
-
-
KBYTES- Displays total number of Kbytes written and read to the
file.
The formatting of open sockets depends on the protocol domain. In all cases the
first field is the domain name and the second field is the socket type
(stream, dgram, etc). 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, it's 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 information 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. These addresses are only visible to the
superuser, otherwise 0x0 is printed. Sockets that have been disassociated from
a protocol control block will always print 0x0. A unidirectional
UNIX-domain socket indicates the direction of flow
with an arrow (“<-” or “->”), and a full
duplex socket shows a double arrow (“<->”).
For
AF_INET and
AF_INET6 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. A
‘
*’ is used to indicate an
INADDR_ANY binding. In this case, the use
of the arrow (“<--” or “-->”) indicates the
direction the socket connection was created.
If the socket has been spliced to or from another socket (see
setsockopt(2) and
SO_SPLICE) then
fstat prints a thick arrow
(“<==>”, “<==”, or
“==>”), followed by the address and endpoint information of
the other socket in the splice, if available.
Every pipe is printed as an address which is the same for both sides of the pipe
and a state that is built of the letters “RWE”. W - The pipe
blocks waiting for the reader to read data. R - The pipe blocks waiting for
the writer to write data. E - The pipe is in EOF state.
Each
kqueue(2) is printed with
some information as to queue length. Since these things are normally serviced
quickly, it is likely that nothing of real importance can be discerned.
netstat(1),
nfsstat(1),
ps(1),
systat(1),
top(1),
iostat(8),
pstat(8),
tcpdrop(8),
vmstat(8)
The
fstat command appeared in
4.3BSD-Tahoe.
Sockets in use by the kernel, such as those opened by
nfsd(8), will not be seen by
fstat, even though they appear in
netstat(1).
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 descriptor
changes,
fstat does not attempt to translate the
internet address and port numbers into symbolic names.
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