usr.bin/fstat/fstat.1

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.Dd November 19, 2020
.Dt FSTAT 1
.Os
.Sh NAME
.Nm fstat
.Nd identify active files
.Sh SYNOPSIS
.Nm
.Op Fl fmnsv
.Op Fl M Ar core
.Op Fl N Ar system
.Op Fl p Ar pid
.Op Fl u Ar user
.Op Ar
.Sh DESCRIPTION
The
.Nm
utility identifies open files.
A file is considered open by a process if it was explicitly opened,
is the working directory, root directory, jail root directory,
active executable text, or kernel trace file for that process.
If no options are specified,
.Nm
reports on all open files in the system for processes the user has access to.
.Pp
The following options are available:
.Bl -tag -width "-N system"
.It Fl 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
.Pa /usr/src
resides, type
.Ql fstat -f /usr/src .
.It Fl M Ar core
Extract values associated with the name list from the specified core
instead of the default
.Pa /dev/kmem .
.It Fl m
Include memory-mapped files in the listing; normally these are excluded
due to the extra processing required.
.It Fl N Ar system
Extract the name list from the specified system instead of the default,
which is the kernel image the system has booted from.
.It Fl 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
.Pa /dev ;
and print the mode of the file in octal instead of symbolic form.
.It Fl p Ar pid
Report all files open by the specified process.
.It Fl s
Print socket endpoint information.
.It Fl u Ar user
Report all files open by the specified user.
.It Fl 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
.Nm
is running.
This
is normal and unavoidable since the rest of the system is running while
.Nm
itself is running.
.It Ar
Restrict reports to the specified files.
.El
.Pp
The following fields are printed:
.Bl -tag -width MOUNT
.It Sy USER
The username of the owner of the process (effective uid).
.It Sy CMD
The command name of the process.
.It Sy PID
The process id.
.It Sy FD
The file number in the per-process open file table or one of the following
special names:
.Pp
.Bl -tag -width jail -offset indent -compact
.It Sy jail
jail root directory
.It Sy mmap
memory-mapped file
.It Sy root
root inode
.It Sy text
executable text inode
.It Sy tr
kernel trace file
.It Sy wd
current working directory
.El
.Pp
If the file number is followed by an asterisk
.Pq Ql * ,
the file is
not an inode, but rather a socket, FIFO, or there is an error.
In this case the remainder of the line does not
correspond to the remaining headers\(em the format of the line
is described later under
.Sx SOCKETS .
.It Sy MOUNT
If the
.Fl n
flag was not specified, this header is present and is the
pathname that the file system the file resides in is mounted on.
.It Sy DEV
If the
.Fl n
flag is specified, this header is present and is the
number of the device that this file resides in.
.It Sy INUM
The inode number of the file.
.It Sy MODE
The mode of the file.
If the
.Fl n
flag is not specified, the mode is printed
using a symbolic format (see
.Xr strmode 3 ) ;
otherwise, the mode is printed
as an octal number.
.It Sy SZ\&|DV
If the file is a semaphore,
prints the current value of the semaphore.
If the file is not a character or block special, prints the size of
the file in bytes.
Otherwise, if the
.Fl n
flag is not specified, prints
the name of the special file as located in
.Pa /dev .
If that cannot be
located, or the
.Fl n
flag is specified, prints the major/minor device
number that the special device refers to.
.It Sy R/W
This column describes the access mode that the file allows.
The letter
.Ql r
indicates open for reading;
the letter
.Ql w
indicates open for writing.
This field is useful when trying to find the processes that are
preventing a file system from being down graded to read-only.
.It Sy NAME
If filename arguments are specified and the
.Fl 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
.Xr ln 1 ) ,
the name printed may not be the actual
name that the process originally used to open that file.
.El
.Sh SOCKETS
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.
.Pp
For example, the addresses mentioned above are the addresses which the
.Ql netstat -A
command would print for TCP, UDP, and UNIX-domain.
Note that since pipes are implemented using sockets, a pipe appears as a
connected UNIX-domain stream socket.
A unidirectional UNIX-domain socket indicates the direction of flow with
an arrow
.Po Ql <-
or
.Ql ->
.Pc ,
and a full duplex socket shows a double arrow
.Pq Ql <-> .
.Pp
When the
.Fl s
flag is used, socket endpoint information is shown after the address of the
socket.
For internet sockets the local and remote addresses are shown, separated with
a double arrow
.Pq Ql <-> .
For UNIX/local sockets either the local or remote address is shown, depending
on which one is available.
.Sh EXIT STATUS
.Ex -std
.Sh EXAMPLES
Show all open files except those opened by
.Nm
itself:
.Bd -literal -offset indent
$ fstat | awk '$2 != "fstat"'
USER     CMD          PID   FD MOUNT      INUM MODE         SZ|DV R/W
alice  bash         469 text /usr/local 143355 -rwxr-xr-x  1166448  r
alice  bash         469 ctty /dev        346 crw--w----  pts/81 rw
\&...
.Ed
.Pp
Report all files opened by the current shell in the same file system as
.Pa /usr/local
including memory-mapped files:
.Bd -literal -offset indent
$ fstat -m -p $$ -f /usr/local
USER     CMD          PID   FD MOUNT      INUM MODE         SZ|DV R/W
bob  bash         469 text /usr/local 143355 -rwxr-xr-x  1166448  r
bob  bash         469 mmap /usr/local 143355 -rwxr-xr-x  1166448  r
\&...
.Ed
.Pp
Requesting information about a file that is not opened results in just a
header line instead of an error:
.Bd -literal -offset indent
$ fstat /etc/rc.conf
USER     CMD          PID   FD MOUNT      INUM MODE         SZ|DV R/W NAME
.Ed
.Pp
All parameters after
.Fl f
will be interpreted as files, so the following will not work as expected:
.Bd -literal -offset indent
$ fstat -f /usr/local -m -p $$
fstat: -m: No such file or directory
fstat: -p: No such file or directory
fstat: 469: No such file or directory
\&...
.Ed
.Pp
Show number of pipes opened by firefox processes:
.Bd -literal -offset indent
$ fstat | awk '$2=="firefox" && $5=="pipe"' | wc -l
.Ed
.Pp
Show processes belonging to user
.Dq bob
whose standard error descriptor is opened in ttyv0:
.Bd -literal -offset indent
$ fstat -u bob | awk '$4 == 2 && $8 == "ttyv0"'
bob  firefox    77842    2 /dev        103 crw-------   ttyv0 rw
bob  xinit       1194    2 /dev        103 crw-------   ttyv0 rw
\&...
.Ed
.Pp
Show opened TCP sockets.
This output resembles the one produced by
.Ql netstat -A -p tcp
:
.Bd -literal -offset indent
$ fstat | awk '$7 == "tcp"'
alice  firefox    77991   32* internet stream tcp fffff800b7f147a0
alice  firefox    77991  137* internet stream tcp fffff800b7f12b70
\&...
.Ed
.Pp
Show a list of processes with files opened in the current directory
mimicking the output of
.Xr fuser 1
:
.Bd -literal -offset indent
$ fstat . | awk 'NR > 1 {printf "%d%s(%s) ", $3, $4, $1;}'
2133wd(alice) 2132wd(alice) 1991wd(alice)
.Ed
.Pp
Create a list of processes sorted by number of opened files in desdencing order:
.Bd -literal -offset indent
$ fstat | awk 'NR > 1 {print $2;}' | sort | uniq -c | sort -r
 728 firefox
  23 bash
  14 sort
   8 fstat
   7 awk
.Ed
.Sh SEE ALSO
.Xr fuser 1 ,
.Xr netstat 1 ,
.Xr nfsstat 1 ,
.Xr procstat 1 ,
.Xr ps 1 ,
.Xr sockstat 1 ,
.Xr systat 1 ,
.Xr tcp 4 ,
.Xr unix 4 ,
.Xr iostat 8 ,
.Xr pstat 8 ,
.Xr vmstat 8
.Sh HISTORY
The
.Nm
command appeared in
.Bx 4.3 tahoe .
.Sh BUGS
Since
.Nm
takes a snapshot of the system, it is only correct for a very short period
of time.