mount_procfs - mount the process file system
mount_procfs [-o options] /proc mount_point
The mount_procfs command attaches an instance of the process
the global filesystem namespace. The conventional mount
point is /proc.
This command is normally executed by mount(8) at boot time.
The options are as follows:
Options are specified with a -o flag followed by a
string of options. See the mount(8) man page for
and their meanings. The following procfs specific option
is also available:
linux Add Linux compatibility links and nodes to
The root of the process filesystem contains an entry for
each active process.
These processes are visible as a directory whose name
is the process's
PID. In addition, the special entry curproc references the current
Each directory contains several files.
Process command line parameters, separated by NULs.
ctl A write-only file which supports a variety of control operations.
Control commands are written as strings to the ctl
control commands are:
attach Stops the target process and arranges for
process to become the debug control process.
detach Continues execution of the target process
and removes it
from control by the debug process (which
need not be the
run Continues running the target process until a
delivered, a breakpoint is hit, or the target process exits.
step Single steps the target process, with no
wait Waits for the target process to come to a
ready for debugging. The target process
must be in this
state before any of the other commands are
The string can also be the name of a signal, lower
case and without
the SIG prefix, in which case that signal is delivered to the
process (see sigaction(2)).
file A reference to the vnode from which the process text
This can be used to gain access to the process's
symbol table, or
to start another copy of the process.
fpregs The floating point registers as defined by struct
<machine/reg.h>. fpregs is only implemented on machines which
have distinct general purpose and floating point
mem The complete virtual memory image of the process.
Only those address
which exist in the process can be accessed.
writes to this file modify the process. Writes to
the text segment
remain private to the process.
note Not implemented.
notepg Not implemented.
regs Allows read and write access to the process's register set. This
file contains a binary data structure struct regs
<machine/reg.h>. regs can only be written when the
status The process status. This file is read-only and returns a single
line containing multiple space-separated fields as
+o Command name.
+o Process ID.
+o Parent process ID.
+o Process group ID.
+o Session ID.
+o major,minor of the controlling terminal, or
-1,-1 if there is
no controlling terminal.
+o List of process flags: ctty if there is a controlling terminal,
sldr if the process is a session leader, or
neither of the other two flags are set.
+o Process start time in seconds and microseconds,
+o User time in seconds and microseconds, comma
+o System time in seconds and microseconds, comma
+o Wait channel message.
+o Process credentials consisting of the effective
user ID and
the list of groups (whose first member is the
ID), all comma separated.
In a normal debugging environment, where the target is
fork/exec'd by the
debugger, the debugger should fork and the child should stop
a self-inflicted SIGSTOP for example). The parent should
issue a wait
and then an attach command via the appropriate ctl file.
The child process
will receive a SIGTRAP immediately after the call to
Statistics reported by df(1) on a procfs filesystem will indicate virtual
memory used/available instead of `disk space', and the number of process
slots used/allocated instead of `inodes'. The block size of
is the system page size.
mount(2), sigaction(2), fstab(5), mount(8), umount(8)
The mount_procfs utility first appeared in 4.4BSD.
This filesystem may not be NFS-exported since most of the
of procfs requires that state be maintained.
OpenBSD 3.6 March 27, 1994
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