.\" $NetBSD: mount_procfs.8,v 1.38.8.1 2024/07/20 15:39:46 martin Exp $ .\" .\" Copyright (c) 1992, 1993 .\" The Regents of the University of California. All rights reserved. .\" All rights reserved. .\" .\" This code is derived from software donated to Berkeley by .\" Jan-Simon Pendry. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)mount_procfs.8 8.3 (Berkeley) 6/1/94 .\" .\" .Dd April 18, 2023 .Dt MOUNT_PROCFS 8 .Os .Sh NAME .Nm mount_procfs .Nd mount the process file system .Sh SYNOPSIS .Nm .Op Fl o Ar options .Pa /proc .Pa mount_point .Sh DESCRIPTION The .Nm command attaches an instance of the process namespace to the global filesystem namespace. The conventional mount point is .Pa /proc . The directory specified by .Ar mount_point is converted to an absolute path before use. This command is normally executed by .Xr mount 8 at boot time. .Pp The options are as follows: .Bl -tag -width indent .It Fl o Cm nolinux Do not support nodes which are not part of the original procfs implementation but have been added for compatibility with the Linux procfs namespace. See .Sx FILES for more information. .El .Pp 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' pid. In addition, the special entries .Pa curproc and .Pa self reference the current process. The .Pa self symlink appears for compatibility with the Linux procfs implementation. .Pp Each directory contains several files. .Bl -tag -width status .It Pa cmdline This file is readonly and returns null-terminated strings corresponding to the process' command line arguments. For a system or zombie process, this file contains only a string with the name of the process. .It Pa cwd A symbolic link that points to the current working directory of the process. If the target process's current working directory is not available or is not at or below the current process's root directory, this link will point to .Dq / . .It Pa fd/# File descriptors which can be accessed through the file system. See .Xr fd 4 for more information. .It Pa file A reference to the vnode from which the process text was read. This can be used to gain access to the process' symbol table, or to start another copy of the process. .It Pa map A map of the process' virtual memory. This file comprises lines describing the memory regions of the process, where each line contains the following fields: .Pp .Bl -tag -compact -width max-protection .It start-address The starting address of the region (inclusive). .It end-address The ending address of the region (exclusive). .It protection The access permissions for the region, represented as a three-character string using the characters .Sq r , .Sq w and .Sq x to denote read, write, and execute permission respectively. The lack of a permission is represented by a .Sq - . .It max-protection The maximum access permissions for the region represented as a three character string using the characters .Sq r , .Sq w and .Sq x to denote read, write, and execute permission respectively. The lack of a permission is represented by a .Sq - . .It copy-on-write Whether the region is copy-on-write. One of: .Bl -tag -compact -width NCOW .It COW A region that is copy-on-write. .It NCOW A region that is not copy-on-write. .El .It needs-copy Whether the region needs a copy. One of: .Bl -tag -compact -width NNC .It NC The region needs a copy. .It NNC The region does not need a copy. .El .It inheritance The inheritance code for the region, as set by .Xr minherit 2 . .It wired-count The wired count for the region. The region can be paged out if its wired count is zero. .It advice The advice value set by a prior call to .Xr madvise 2 for the region. .El .It Pa maps A map of the process' virtual memory in a form like the proc filesystem as implemented in Linux. This file comprises lines describing the memory regions of the process, where each line contains the following fields: .Pp .Bl -tag -compact -width start-address .It start-address The starting address of the region (inclusive). .It end-address The ending address of the region (exclusive). .It protection The access permissions for the region, represented as a three-character string using the characters .Sq r , .Sq w and .Sq x to denote read, write, and execute permission respectively. The lack of a permission is represented by a .Sq - . .It copy-on-write Whether the region is copy-on-write. One of: .Bl -tag -compact -width ".Sq p" .It Sq p The region is copy-on-write. .It Sq s The region is shared. .El .It offset The offset into the file being mapped by the region. .It device-id The major and minor number of the device containing the file being mapped by the region. .It fileid The inode for the file associated with the region. .It path The pathname to the file associated with the region. .El .It Pa mem The complete virtual memory image of the process. Only those addresses which exist in the process can be accessed. Writes to this file modify the process. Writes to the text segment normally remain private to the process, since the text segment is mapped with MAP_PRIVATE; however, this is not guaranteed. .It Pa note Not implemented. .It Pa notepg Not implemented. .It Pa regs Allows read and write access to the process' register set. This file contains a binary data structure .Dv "struct regs" defined in .Pa <machine/reg.h> . .Pa regs can only be written when the process is stopped. .It Pa fpregs The floating point registers as defined by .Dv "struct fpregs" in .Pa <machine/reg.h> . .Pa fpregs is only implemented on machines which have distinct general purpose and floating point register sets. .It Pa root A symbolic link that points to the root directory of the process. If the target process's root directory is not available or is not at or below the current process's root directory, this link will point to .Dq / . .It Pa status The process status. This file is readonly and returns a single line containing multiple space-separated fields as follows: .Pp .Bl -bullet -compact .It command name .It process id .It parent process id .It process group id .It session id .It .Ar major,minor of the controlling terminal, or .Dv -1,-1 if there is no controlling terminal. .It a list of process flags: .Dv ctty if there is a controlling terminal, .Dv sldr if the process is a session leader, .Dv noflags if neither of the other two flags are set. .It the process start time in seconds and microseconds, comma separated. .It the user time in seconds and microseconds, comma separated. .It the system time in seconds and microseconds, comma separated. .It the wait channel message .It the process credentials consisting of the effective user id and the list of groups (whose first member is the effective group id) all comma separated. .El .El .Sh FILES .Bl -tag -width /proc/curproc -compact .It Pa /proc/# .It Pa /proc/#/cmdline .It Pa /proc/#/cwd .It Pa /proc/#/exe .It Pa /proc/#/file .It Pa /proc/#/fpregs .It Pa /proc/#/map .It Pa /proc/#/maps .It Pa /proc/#/mem .It Pa /proc/#/note .It Pa /proc/#/notepg .It Pa /proc/#/regs .It Pa /proc/#/root .It Pa /proc/#/status .It Pa /proc/curproc .It Pa /proc/self .El .Pp If the .Cm linux mount option is used, the following files are also available: .Pp .Bl -tag -width /proc/meminfo -compact .It Pa /proc/#/stat .It Pa /proc/cpuinfo .It Pa /proc/devices .It Pa /proc/meminfo .It Pa /proc/mounts .It Pa /proc/uptime .El .Sh SEE ALSO .Xr mount 2 , .Xr sigaction 2 , .Xr unmount 2 .Sh HISTORY The .Nm utility first appeared in .Bx 4.4 . .Sh BUGS This filesystem may not be NFS-exported since most of the functionality of .Dv procfs requires that state be maintained.