1130b656e5
This will make a number of things easier in the future, as well as (finally!) avoiding the Id-smashing problem which has plagued developers for so long. Boy, I'm glad we're not using sup anymore. This update would have been insane otherwise.
223 lines
5.5 KiB
Groff
223 lines
5.5 KiB
Groff
.\" $FreeBSD$
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.\" Written by Garrett Wollman
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.\" This file is in the public domain.
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.\"
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.Dd August 10, 1994
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.Dt PROCFS 5
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.Os BSD 4.4
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.Sh NAME
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.Nm procfs
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.Nd process file system
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.Sh SYNOPSIS
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.Bd -literal
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proc /proc procfs rw 0 0
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.Ed
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.Sh DESCRIPTION
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The process file system, or
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.Nm procfs ,
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implements a view of the system process table inside the file system.
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It is normally mounted on
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.Pa /proc ,
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and is required for the complete operation of programs such as
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.Xr ps 1
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and
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.Xr w 1 .
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.Pp
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The
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.Nm
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provides a two-level view of process space, unlike the previous
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.Fx 1.1
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.Nm
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implementation.
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At the highest level, processes themselves are named, according to
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their process ids in decimal, with no leading zeros. There is also a
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special node called
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.Pa curproc
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which always refers to the process making the lookup request.
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.Pp
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Each node is a directory which contains the following entries:
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.Pp
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Each directory contains several files:
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.Bl -tag -width status
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.It Pa ctl
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a write-only file which supports a variety
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of control operations.
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Control commands are written as strings to the
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.Pa ctl
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file.
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The control commands are:
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.Bl -tag -width detach -compact
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.It attach
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stops the target process and arranges for the sending
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process to become the debug control process.
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.It detach
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continue execution of the target process and
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remove it from control by the debug process (which
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need not be the sending process).
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.It run
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continue running the target process until
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a signal is delivered, a breakpoint is hit, or the
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target process exits.
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.It step
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single step the target process, with no signal delivery.
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.It wait
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wait for the target process to come to a steady
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state ready for debugging.
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The target process must be in this state before
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any of the other commands are allowed.
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.El
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.Pp
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The string can also be the name of a signal, lower case
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and without the
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.Dv SIG
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prefix,
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in which case that signal is delivered to the process
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(see
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.Xr sigaction 2 ).
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.It Pa etype
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The type of the executable referenced by the
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.Pa file
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entry.
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.It Pa file
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A reference to the vnode from which the process text was read.
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This can be used to gain access to the process' symbol table,
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or to start another copy of the process.
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.It Pa fpregs
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The floating point registers as defined by
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.Dv "struct fpregs"
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in
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.Pa <machine/reg.h> .
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.Pa fpregs
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is only implemented on machines which have distinct general
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purpose and floating point register sets.
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.It Pa map
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A map of the process' virtual memory.
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.It Pa mem
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The complete virtual memory image of the process.
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Only those address which exist in the process can be accessed.
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Reads and writes to this file modify the process.
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Writes to the text segment remain private to the process.
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.It Pa note
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Used for sending signals to the process. Not implemented.
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.It Pa notepg
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Used for sending signal to the process group. Not implemented.
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.It Pa regs
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Allows read and write access to the process' register set.
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This file contains a binary data structure
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.Dv "struct regs"
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defined in
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.Pa <machine/reg.h> .
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.Pa regs
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can only be written when the process is stopped.
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.It Pa status
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The process status.
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This file is read-only and returns a single line containing
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multiple space-separated fields as follows:
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.Pp
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.Bl -bullet -compact
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.It
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command name
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.It
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process id
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.It
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parent process id
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.It
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process group id
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.It
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session id
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.It
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.Ar major,minor
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of the controlling terminal, or
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.Dv -1,-1
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if there is no controlling terminal.
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.It
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a list of process flags:
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.Dv ctty
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if there is a controlling terminal,
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.Dv sldr
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if the process is a session leader,
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.Dv noflags
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if neither of the other two flags are set.
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.It
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the process start time in seconds and microseconds,
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comma separated.
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.It
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the user time in seconds and microseconds,
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comma separated.
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.It
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the system time in seconds and microseconds,
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comma separated.
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.It
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the wait channel message
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.It
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the process credentials consisting of
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the effective user id
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and the list of groups (whose first member
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is the effective group id)
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all comma separated.
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.El
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.El
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.Pp
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In a normal debugging environment,
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where the target is fork/exec'd by the debugger,
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the debugger should fork and the child should stop
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itself (with a self-inflicted
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.Dv SIGSTOP
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for example).
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The parent should issue a
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.Dv wait
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and then an
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.Dv attach
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command via the appropriate
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.Pa ctl
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file.
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The child process will receive a
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.Dv SIGTRAP
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immediately after the call to exec (see
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.Xr execve 2 ).
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.Pp
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Each node is owned by the process's user, and belongs to that user's
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primary group, except for the
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.Pa mem
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node, which belongs to the
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.Li kmem
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.Sh FILES
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.Bl -tag -width /proc/curproc/XXXXXXX -compact
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.It Pa /proc
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normal mount point for the
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.Nm procfs .
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.It Pa /proc/pid
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directory containing process information for process
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.Pa pid .
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.It Pa /proc/curproc
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directory containing process information for the current process
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.It Pa /proc/curproc/ctl
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used to send control messages to the process
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.It Pa /proc/curproc/etype
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executable type
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.It Pa /proc/curproc/file
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executable image
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.It Pa /proc/curproc/fpregs
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the process floating point register set
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.It Pa /proc/curproc/map
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virtual memory map of the process
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.It Pa /proc/curproc/mem
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the complete virtual address space of the process
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.It Pa /proc/curproc/note
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used for signaling the process
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.It Pa /proc/curproc/notepg
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used for signaling the process group
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.It Pa /proc/curproc/regs
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the process register set
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.It Pa /proc/curproc/status
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the process' current status
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.El
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.Sh SEE ALSO
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.Xr mount 2 ,
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.Xr sigaction 2 ,
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.Xr unmount 2 ,
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.Xr mount_procfs 8
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.Sh AUTHOR
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This manual page written by Garrett Wollman, based on the description
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provided by Jan-Simon Pendry, and revamped later by Mike Pritchard.
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