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MOUNT_PROCFS(8) System Manager's Manual MOUNT_PROCFS(8)
NAME
mount_procfs - mount the process file system
SYNOPSIS
mount_procfs [-o options] /proc mount_point
DESCRIPTION
The mount_procfs command attaches an instance of the process namespace to
the global filesystem namespace. The conventional mount point is /proc.
The directory specified by mount_point is converted to an absolute path
before use. This command is normally executed by mount(8) at boot time.
The options are as follows:
-o 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 FILES for more information.
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 curproc and self
reference the current process. The self symlink appears for
compatibility with the Linux procfs implementation.
Each directory contains several files.
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.
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 "/".
fd/# File descriptors which can be accessed through the file system.
See fd(4) for more information.
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.
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:
start-address The starting address of the region (inclusive).
end-address The ending address of the region (exclusive).
protection The access permissions for the region,
represented as a three-character string using the
characters `r', `w' and `x' to denote read,
write, and execute permission respectively. The
lack of a permission is represented by a `-'.
max-protection The maximum access permissions for the region
represented as a three character string using the
characters `r', `w' and `x' to denote read,
write, and execute permission respectively. The
lack of a permission is represented by a `-'.
copy-on-write Whether the region is copy-on-write. One of:
COW A region that is copy-on-write.
NCOW A region that is not copy-on-write.
needs-copy Whether the region needs a copy. One of:
NC The region needs a copy.
NNC The region does not need a copy.
inheritance The inheritance code for the region, as set by
minherit(2).
wired-count The wired count for the region. The region can
be paged out if its wired count is zero.
advice The advice value set by a prior call to
madvise(2) for the region.
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:
start-address The starting address of the region (inclusive).
end-address The ending address of the region (exclusive).
protection The access permissions for the region, represented
as a three-character string using the characters
`r', `w' and `x' to denote read, write, and
execute permission respectively. The lack of a
permission is represented by a `-'.
copy-on-write Whether the region is copy-on-write. One of:
`p' The region is copy-on-write.
`s' The region is shared.
offset The offset into the file being mapped by the
region.
device-id The major and minor number of the device
containing the file being mapped by the region.
fileid The inode for the file associated with the region.
path The pathname to the file associated with the
region.
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.
note Not implemented.
notepg Not implemented.
regs Allows read and write access to the process' register set. This
file contains a binary data structure struct regs defined in
<machine/reg.h>. regs can only be written when the process is
stopped.
fpregs The floating point registers as defined by struct fpregs in
<machine/reg.h>. fpregs is only implemented on machines which
have distinct general purpose and floating point register sets.
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 "/".
status The process status. This file is readonly and returns a single
line containing multiple space-separated fields as follows:
⊕ command name
⊕ process id
⊕ parent process id
⊕ process group id
⊕ session id
⊕ major,minor of the controlling terminal, or -1,-1 if there is
no controlling terminal.
⊕ a list of process flags: ctty if there is a controlling
terminal, sldr if the process is a session leader, noflags if
neither of the other two flags are set.
⊕ the process start time in seconds and microseconds, comma
separated.
⊕ the user time in seconds and microseconds, comma separated.
⊕ the system time in seconds and microseconds, comma separated.
⊕ the wait channel message
⊕ 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.
FILES
/proc/#
/proc/#/cmdline
/proc/#/cwd
/proc/#/exe
/proc/#/file
/proc/#/fpregs
/proc/#/map
/proc/#/maps
/proc/#/mem
/proc/#/note
/proc/#/notepg
/proc/#/regs
/proc/#/root
/proc/#/status
/proc/curproc
/proc/self
If the linux mount option is used, the following files are also
available:
/proc/#/stat
/proc/cpuinfo
/proc/devices
/proc/meminfo
/proc/mounts
/proc/uptime
SEE ALSO
mount(2), sigaction(2), unmount(2)
HISTORY
The mount_procfs utility first appeared in 4.4BSD.
BUGS
This filesystem may not be NFS-exported since most of the functionality
of procfs requires that state be maintained.
NetBSD 10.99 April 18, 2023 NetBSD 10.99