.\" 2005-07-13, mtk, added /proc/sys/fs/mqueue/*
.\" 2005-09-16, mtk, Added /proc/sys/fs/suid_dumpable
.\" 2005-09-19, mtk, added /proc/zoneinfo
-.\" 2005-03-01, mtk, moved /proc/sys/fs/mqueue/* material to
+.\" 2005-03-01, mtk, moved /proc/sys/fs/mqueue/* material to
.\" mq_overview.7.
.\"
.\" FIXME 2.6.14 has /proc/PID/numa_maps (if CONFIG_NUMA is
.\" enabled); this needs to be documented.
-.\" Info on numa_maps can be found in the patch-2.6.14
+.\" Info on numa_maps can be found in the patch-2.6.14
.\" Changelog, but this is possibly not up to date.
.\"
.\" FIXME 2.6.13 seems to have /proc/vmcore implemented
-.\" in the source code, but there is no option available under
-.\" 'make xconfig'; eventually this should be fixed, and then info
-.\" from the patch-2.6.13 and change log could be used to write an
+.\" in the source code, but there is no option available under
+.\" 'make xconfig'; eventually this should be fixed, and then info
+.\" from the patch-2.6.13 and change log could be used to write an
.\" entry in this man page.
.\"
-.\" FIXME cross check against Documentation/filesystems/proc.txt
-.\" to see what information could be imported from that file
+.\" FIXME cross check against Documentation/filesystems/proc.txt
+.\" to see what information could be imported from that file
.\" into this file.
.\"
.TH PROC 5 2005-05-12 "" "Linux Programmer's Manual"
The
.I proc
filesystem is a pseudo-filesystem which is used as an interface to
-kernel data structures. It is commonly mounted at
+kernel data structures.
+It is commonly mounted at
.IR /proc .
-Most of it is read-only, but some files allow kernel variables to be
+Most of it is read-only, but some files allow kernel variables to be
changed.
.LP
The following outline gives a quick tour through the /proc hierarchy.
.TP
.IR /proc/[number]/auxv " (since 2.6.0-test7)"
This contains the contents of the ELF interpreter information passed
-to the process at exec time.
+to the process at exec time.
The format is one \fIunsigned long\fP ID
-plus one \fIunsigned long\fP value for each entry.
+plus one \fIunsigned long\fP value for each entry.
The last entry contains two zeros.
.TP
.I /proc/[number]/cmdline
This holds the complete command line for the process, unless the whole
-process has been swapped out or the process is a zombie. In
-either of these latter cases, there is nothing in this file: i.e. a
+process has been swapped out or the process is a zombie.
+In either of these latter cases, there is nothing in this file: i.e. a
read on this file will return 0 characters.
-The command line arguments appear in this file as a set of
+The command line arguments appear in this file as a set of
null-separated strings, with a further null byte after the last string.
.TP
.I /proc/[number]/cwd
-This is a symbolic link to the current working directory of the process.
+This is a symbolic link to the current working directory of the process.
To find out the cwd of process 20, for instance, you can do this:
.br
.fi
.ft
-Note that the
-.I pwd
+Note that the
+.I pwd
command is often a shell builtin, and might
-not work properly. In bash, you may use pwd \-P.
+not work properly.
+In bash, you may use pwd \-P.
.\" The following was still true as at kernel 2.6.13
-In a multithreaded process, the contents of this symbolic link
-are not available if the main thread has already terminated
+In a multithreaded process, the contents of this symbolic link
+are not available if the main thread has already terminated
(typically by calling
.BR pthread_exit (3).
.TP
.I /proc/[number]/exe
Under Linux 2.2 and later, this file is a symbolic link
containing the actual pathname of the executed command.
-This symbolic link can be dereferenced normally; attempting to open
-it will open the executable. You can even type
+This symbolic link can be dereferenced normally; attempting to open
+it will open the executable.
+You can even type
.I /proc/[number]/exe
-to run another copy of the same executable as is being run by
+to run another copy of the same executable as is being run by
process [number].
.\" The following was still true as at kernel 2.6.13
-In a multithreaded process, the contents of this symbolic link
-are not available if the main thread has already terminated
+In a multithreaded process, the contents of this symbolic link
+are not available if the main thread has already terminated
(typically by calling
.BR pthread_exit (3)).
Under Linux 2.0 and earlier
.I /proc/[number]/exe
-is a pointer to the binary which was executed,
-and appears as a symbolic link. A
+is a pointer to the binary which was executed,
+and appears as a symbolic link.
+A
.BR readlink (2)
call on this file under Linux 2.0 returns a string in the format:
.I /proc/[number]/fd
This is a subdirectory containing one entry for each file which the
process has open, named by its file descriptor, and which is a
-symbolic link to the actual file. Thus, 0 is
-standard input, 1 standard output, 2 standard error, etc.
+symbolic link to the actual file.
+Thus, 0 is standard input, 1 standard output, 2 standard error, etc.
.\" The following was still true as at kernel 2.6.13
In a multithreaded process, the contents of this directory
-are not available if the main thread has already terminated
+are not available if the main thread has already terminated
(typically by calling
.BR pthread_exit (3)).
.\" are not seekable.
/proc/self/fd/N is approximately the same as /dev/fd/N in some UNIX
-and UNIX-like systems. Most Linux MAKEDEV scripts symbolically link
+and UNIX-like systems.
+Most Linux MAKEDEV scripts symbolically link
/dev/fd to /proc/self/fd, in fact.
.\" FIXME Describe /proc/[number]/loginuid
.\" Added in 2.6.11; updating requires CAP_AUDIT_CONTROL
Unix and Linux support the idea of a per-process root of the
filesystem, set by the
.BR chroot (2)
-system call. This file is a symbolic link that points to the process's
+system call.
+This file is a symbolic link that points to the process's
root directory, and behaves as exe, fd/*, etc. do.
.\" The following was still true as at kernel 2.6.13
-In a multithreaded process, the contents of this symbolic link
-are not available if the main thread has already terminated
+In a multithreaded process, the contents of this symbolic link
+are not available if the main thread has already terminated
(typically by calling
.BR pthread_exit (3)).
.\" FIXME Describe /proc/[number]/seccomp
the number clean and dirty shared pages in the mapping,
and the number clean and dirty private pages in the mapping.
-This file is only present if the CONFIG_MMU kernel configuration
+This file is only present if the CONFIG_MMU kernel configuration
option is enabled.
.TP
.I /proc/[number]/stat
-Status information about the process. This is used by
-.BR ps (1).
-It is defined in
+Status information about the process.
+This is used by
+.BR ps (1).
+It is defined in
.IR /usr/src/linux/fs/proc/array.c "."
The fields, in order, with their proper
The process ID.
.TP
\fIcomm\fP %s
-The filename of the executable, in parentheses. This is visible
-whether or not the executable is swapped out.
+The filename of the executable, in parentheses.
+This is visible whether or not the executable is swapped out.
.TP
\fIstate\fP %c
One character from the string "RSDZTW" where R is running, S is
the process is connected to.
.TP
\fIflags\fP %lu
-The kernel flags word of the process. For bit meanings,
+The kernel flags word of the process.
+For bit meanings,
see the PF_* defines in
.IR <linux/sched.h> .
Details depend on the kernel version.
.TP
\fIcutime\fP %ld
The number of jiffies that this process's
-waited-for children have been scheduled in user mode. (See also
+waited-for children have been scheduled in user mode.
+(See also
.BR times (2).)
.TP
\fIcstime\fP %ld
waited-for children have been scheduled in kernel mode.
.TP
\fIpriority\fP %ld
-The standard nice value, plus fifteen. The value is never negative in
-the kernel.
+The standard nice value, plus fifteen.
+The value is never negative in the kernel.
.TP
\fInice\fP %ld
The nice value ranges from 19 (nicest) to \-19 (not nice to others).
.TP
\fIrss\fP %ld
Resident Set Size: number of pages the process has in real memory,
-minus 3 for administrative purposes. This is just the pages which
-count towards text, data, or stack space. This does not include pages
+minus 3 for administrative purposes.
+This is just the pages which
+count towards text, data, or stack space.
+This does not include pages
which have not been demand-loaded in, or which are swapped out.
.TP
\fIrlim\fP %lu
The bitmap of caught signals.
.TP
\fIwchan\fP %lu
-This is the "channel" in which the process is waiting. It is the
+This is the "channel" in which the process is waiting.
+It is the
address of a system call, and can be looked up in a namelist if you
-need a textual name. (If you have an up-to-date /etc/psdatabase, then
+need a textual name.
+(If you have an up-to-date /etc/psdatabase, then
try \fIps \-l\fP to see the WCHAN field in action.)
.TP
\fInswap\fP %lu
.RE
.TP
.I /proc/[number]/statm
-Provides information about memory status in pages. The columns are:
+Provides information about memory status in pages.
+The columns are:
size total program size
resident resident set size
share shared pages
each of the files under the
.I task/[thread-ID]
subdirectories will be the same as in the corresponding
-file in the parent
+file in the parent
.I /proc/[number]
directory
-(e.g., in a multithreaded process, all of the
+(e.g., in a multithreaded process, all of the
.I task/[thread-ID]/cwd
-files will have the same value as the
+files will have the same value as the
.I /proc/[number]/cwd
-file in the parent directory, since all of the threads in a process
+file in the parent directory, since all of the threads in a process
share a working directory).
For attributes that are distinct for each thread,
-the corresponding files under
+the corresponding files under
.I task/[thread-ID]
may have different values (e.g., various fields in each of the
.I task/[thread-ID]/status
.\" The following was still true as at kernel 2.6.13
In a multithreaded process, the contents of the
.I /proc/[number]/task
-directory are not available if the main thread has already terminated
+directory are not available if the main thread has already terminated
(typically by calling
.BR pthread_exit (3)).
.TP
.I /proc/bus/pccard/drivers
.TP
.I /proc/bus/pci
-Contains various bus subdirectories and pseudo-files containing
-information about pci busses, installed devices, and device
-drivers. Some of these files are not ASCII.
+Contains various bus subdirectories and pseudo-files containing
+information about pci busses, installed devices, and device
+drivers.
+Some of these files are not ASCII.
.TP
.I /proc/bus/pci/devices
-Information about pci devices. They may be accessed through
+Information about pci devices.
+They may be accessed through
.BR lspci (8)
and
.BR setpci (8).
.TP
.I /proc/cmdline
-Arguments passed to the Linux kernel at boot time. Often done via
-a boot manager such as
+Arguments passed to the Linux kernel at boot time.
+Often done via a boot manager such as
.BR lilo (1).
.\" FIXME Document /proc/config.gz (new in kernel 2.6)
.TP
This is a collection of CPU and system architecture dependent items,
for each supported architecture a different list.
Two common entries are \fIprocessor\fP which gives CPU number and
-\fIbogomips\fP; a system constant that is calculated
-during kernel initialization. SMP machines have information for
+\fIbogomips\fP; a system constant that is calculated
+during kernel initialization.
+SMP machines have information for
each CPU.
.TP
.I /proc/devices
-Text listing of major numbers and device groups. This can be used by
-MAKEDEV scripts for consistency with the kernel.
+Text listing of major numbers and device groups.
+This can be used by MAKEDEV scripts for consistency with the kernel.
.TP
.IR /proc/diskstats " (since Linux 2.5.69)"
This file contains disk I/O statistics for each disk device.
for further information.
.TP
.I /proc/dma
-This is a list of the registered \fIISA\fP DMA (direct memory access)
+This is a list of the registered \fIISA\fP DMA (direct memory access)
channels in use.
.TP
.I /proc/driver
List of the execution domains (ABI personalities).
.TP
.I /proc/fb
-Frame buffer information when CONFIG_FB is defined during kernel
+Frame buffer information when CONFIG_FB is defined during kernel
compilation.
.TP
.I /proc/filesystems
.TP
.I /proc/ide
This directory
-exists on systems with the ide bus. There are directories for each
-ide channel and attached device. Files include:
+exists on systems with the ide bus.
+There are directories for each ide channel and attached device.
+Files include:
.nf
cache buffer size in KB
smart_values in hexadecimal
.fi
-The
+The
.BR hdparm (8)
utility provides access to this information in a friendly format.
.TP
.I /proc/interrupts
This is used to record the number of interrupts per each IRQ on (at
-least) the i386 architecture. Very easy to read formatting, done in
+least) the i386 architecture.
+Very easy to read formatting, done in
ASCII.
.TP
.I /proc/iomem
I/O memory map in Linux 2.4.
.TP
.I /proc/ioports
-This is a list of currently registered Input-Output port regions that
+This is a list of currently registered Input-Output port regions that
are in use.
.TP
.IR /proc/kallsyms " (since Linux 2.5.71)"
.TP
.I /proc/kcore
This file represents the physical memory of the system and is stored
-in the ELF core file format. With this pseudo-file, and an unstripped
+in the ELF core file format.
+With this pseudo-file, and an unstripped
kernel (/usr/src/linux/vmlinux) binary, GDB can be used to
examine the current state of any kernel data structures.
.I /proc/kmsg
This file can be used instead of the
.BR syslog (2)
-system call to read kernel messages. A process must have superuser
+system call to read kernel messages.
+A process must have superuser
privileges to read this file, and only one process should read this
-file. This file should not be read if a syslog process is running
+file.
+This file should not be read if a syslog process is running
which uses the
.BR syslog (2)
system call facility to log kernel messages.
and other programs.
The fourth field consists of two numbers separated by a slash (/).
The first of these is the number of currently executing kernel
-scheduling entities (processes, threads);
+scheduling entities (processes, threads);
this will be less than or equal to the number of CPUs.
The value after the slash is the number of kernel scheduling entities
that currently exist on the system.
This is a list of all the file systems currently mounted on the system.
The format of this file is documented in
.BR fstab (5).
-Since kernel version 2.6.15, this file is pollable:
+Since kernel version 2.6.15, this file is pollable:
after opening the file for reading, a change in this file
(i.e., a file system mount or unmount) causes
.BR select (2)
.BR lsmod (8).
.TP
.I /proc/mtrr
-Memory Type Range Registers.
-See
+Memory Type Range Registers.
+See
.I /usr/src/linux/Documentation/mtrr.txt
for details.
.TP
.I /proc/net
various net pseudo-files, all of which give the status of some part of
-the networking layer. These files contain ASCII structures and are,
-therefore, readable with cat. However, the standard
+the networking layer.
+These files contain ASCII structures and are,
+therefore, readable with cat.
+However, the standard
.BR netstat (8)
suite provides much cleaner access to these files.
.TP
.I /proc/net/arp
This holds an ASCII readable dump of the kernel ARP table used for
-address resolutions. It will show both dynamically learned and
-pre-programmed ARP entries. The format is:
+address resolutions.
+It will show both dynamically learned and
+pre-programmed ARP entries.
+The format is:
.nf
.ft CW
.in
Here 'IP address' is the IPv4 address of the machine and the 'HW type'
-is the hardware type of the address from RFC\ 826.
-The flags are the internal
+is the hardware type of the address from RFC\ 826.
+The flags are the internal
flags of the ARP structure (as defined in /usr/include/linux/if_arp.h) and
the 'HW address' is the data link layer mapping for that IP address if
it is known.
.TP
.I /proc/net/dev
-The dev pseudo-file contains network device status information. This gives
-the number of received and sent packets, the number of errors and
+The dev pseudo-file contains network device status information.
+This gives
+the number of received and sent packets, the number of errors and
collisions
-and other basic statistics. These are used by the
+and other basic statistics.
+These are used by the
.BR ifconfig (8)
-program to report device status. The format is:
+program to report device status.
+The format is:
.nf
.ft CW
.fi
.TP
.I /proc/net/igmp
-Internet Group Management Protocol. Defined in
+Internet Group Management Protocol.
+Defined in
.IR /usr/src/linux/net/core/igmp.c .
.TP
.I /proc/net/rarp
.I arp
file and contains the current reverse mapping database used to provide
.BR rarp (8)
-reverse address lookup services. If RARP is not configured into the
+reverse address lookup services.
+If RARP is not configured into the
kernel,
this file will not be present.
.TP
.I /proc/net/raw
-Holds a dump of the RAW socket table. Much of the information is not of
+Holds a dump of the RAW socket table.
+Much of the information is not of
use
-apart from debugging. The 'sl' value is the kernel hash slot for the
+apart from debugging.
+The 'sl' value is the kernel hash slot for the
socket,
the 'local address' is the local address and protocol number pair."St" is
-the internal status of the socket. The "tx_queue" and "rx_queue" are the
+the internal status of the socket.
+The "tx_queue" and "rx_queue" are the
outgoing and incoming data queue in terms of kernel memory usage.
The "tr", "tm->when", and "rexmits" fields are not used by RAW.
The "uid"
.\" .BR route (8).
.TP
.I /proc/net/snmp
-This file holds the ASCII data needed for the IP, ICMP, TCP, and UDP
+This file holds the ASCII data needed for the IP, ICMP, TCP, and UDP
management
-information bases for an snmp agent.
+information bases for an snmp agent.
.TP
.I /proc/net/tcp
-Holds a dump of the TCP socket table. Much of the information is not
-of use apart from debugging. The "sl" value is the kernel hash slot
+Holds a dump of the TCP socket table.
+Much of the information is not
+of use apart from debugging.
+The "sl" value is the kernel hash slot
for the socket, the "local address" is the local address and port number pair.
The "remote address" is the remote address and port number pair
(if connected). 'St' is the internal status of the socket.
field holds the effective UID of the creator of the socket.
.TP
.I /proc/net/udp
-Holds a dump of the UDP socket table. Much of the information is not of
-use apart from debugging. The "sl" value is the kernel hash slot for the
+Holds a dump of the UDP socket table.
+Much of the information is not of
+use apart from debugging.
+The "sl" value is the kernel hash slot for the
socket, the "local address" is the local address and port number pair.
The "remote address" is the remote address and port number pair
(if connected). "St" is the internal status of the socket.
The "tx_queue" and "rx_queue" are the outgoing and incoming data queue
-in terms of kernel memory usage. The "tr", "tm->when", and "rexmits" fields
-are not used by UDP.
+in terms of kernel memory usage.
+The "tr", "tm->when", and "rexmits" fields
+are not used by UDP.
The "uid"
field holds the effective UID of the creator of the socket.
The format is:
.TP
.I /proc/net/unix
Lists the UNIX domain sockets present within the system and their
-status. The format is:
+status.
+The format is:
.nf
.sp .5
.ft CW
Here 'Num' is the kernel table slot number, 'RefCount' is the number
of users of the socket, 'Protocol' is currently always 0, 'Flags'
represent the internal kernel flags holding the status of the
-socket. Currently, type is always '1' (Unix domain datagram sockets are
+socket.
+Currently, type is always '1' (Unix domain datagram sockets are
not yet supported in the kernel). 'St' is the internal state of the
socket and Path is the bound path (if any) of the socket.
.TP
and their configuration.
.TP
.I /proc/scsi
-A directory with the scsi mid-level pseudo-file and various SCSI lowlevel
-driver
-directories, which contain a file for each SCSI host in this system, all
-of
-which give the status of some part of the SCSI IO subsystem.
-These files contain ASCII structures and are, therefore, readable with
-cat.
+A directory with the scsi mid-level pseudo-file and various SCSI lowlevel
+driver
+directories, which contain a file for each SCSI host in this system, all
+of
+which give the status of some part of the SCSI IO subsystem.
+These files contain ASCII structures and are, therefore, readable with
+cat.
-You can also write to some of the files to reconfigure the subsystem or
+You can also write to some of the files to reconfigure the subsystem or
switch
certain features on or off.
.TP
.I /proc/scsi/scsi
-This is a listing of all SCSI devices known to the kernel. The listing is
+This is a listing of all SCSI devices known to the kernel.
+The listing is
similar to the one seen during bootup.
-scsi currently supports only the \fIadd-single-device\fP command which
+scsi currently supports only the \fIadd-single-device\fP command which
allows
root to add a hotplugged device to the list of known devices.
-An
-.B echo 'scsi add-single-device 1 0 5 0' > /proc/scsi/scsi
-will cause
-host scsi1 to scan on SCSI channel 0 for a device on ID 5 LUN 0. If there
+An
+.B echo 'scsi add-single-device 1 0 5 0' > /proc/scsi/scsi
+will cause
+host scsi1 to scan on SCSI channel 0 for a device on ID 5 LUN 0.
+If there
is already a device known on this address or the address is invalid, an
error will be returned.
.TP
.I /proc/scsi/[drivername]
-\fI[drivername]\fP can currently be NCR53c7xx, aha152x, aha1542, aha1740,
-aic7xxx, buslogic, eata_dma, eata_pio, fdomain, in2000, pas16, qlogic,
-scsi_debug, seagate, t128, u15-24f, ultrastore, or wd7000.
-These directories show up for all drivers that registered at least one
-SCSI
-HBA. Every directory contains one file per registered host. Every
+\fI[drivername]\fP can currently be NCR53c7xx, aha152x, aha1542, aha1740,
+aic7xxx, buslogic, eata_dma, eata_pio, fdomain, in2000, pas16, qlogic,
+scsi_debug, seagate, t128, u15-24f, ultrastore, or wd7000.
+These directories show up for all drivers that registered at least one
+SCSI
+HBA.
+Every directory contains one file per registered host.
+Every
host-file is named after the number the host was assigned during
-initialization.
+initialization.
-Reading these files will usually show driver and host configuration,
+Reading these files will usually show driver and host configuration,
statistics etc.
Writing to these files allows different things on different hosts.
For example, with the \fIlatency\fP and \fInolatency\fP commands,
root can switch on and off command latency measurement code in the
-eata_dma driver. With the \fIlockup\fP and \fIunlock\fP commands,
-root can control bus lockups simulated by the scsi_debug driver.
+eata_dma driver.
+With the \fIlockup\fP and \fIunlock\fP commands,
+root can control bus lockups simulated by the scsi_debug driver.
.TP
.I /proc/self
This directory refers to the process accessing the /proc filesystem,
same process.
.TP
.I /proc/slabinfo
-Information about kernel caches. The columns are:
+Information about kernel caches.
+The columns are:
.nf
cache-name
num-active-objs
total-slabs
num-pages-per-slab
.fi
-See
+See
.BR slabinfo (5)
for details.
.TP
.I /proc/stat
-kernel/system statistics. Varies with architecture. Common
+kernel/system statistics.
+Varies with architecture.
+Common
entries include:
.RS
.TP
that the system spent in user mode,
user mode with low priority (nice), system mode, and the
idle task, respectively.
-.\" FIXME Actually, the following info abut the /proc/stat 'cpu' field
+.\" FIXME Actually, the following info abut the /proc/stat 'cpu' field
.\" does not seem to be quite right (at least in 2.6.12)
The last value should be USER_HZ times the
second entry in the uptime pseudo-file.
\- time servicing interrupts (since 2.6.0-test4);
.I softirq
\- time servicing softirqs (since 2.6.0-test4).
-.\" FIXME 2.6.11 adds a further column "steal" (see
+.\" FIXME 2.6.11 adds a further column "steal" (see
.\" fs/proc/proc_misc.c); this is not yet described...
.TP
\fIpage 5741 1808\fP
\fIswap 1 0\fP
The number of swap pages that have been brought in and out.
.TP
-.\" FIXME The following is not the full picture for the 'intr' of
+.\" FIXME The following is not the full picture for the 'intr' of
.\" /proc/stat on 2.6:
\fIintr 1462898\fP
This line shows counts of interrupts serviced since boot time,
.RE
.TP
.I /proc/swaps
-Swap areas in use. See also
+Swap areas in use.
+See also
.BR swapon (8).
.TP
.I /proc/sys
These variables can be read and sometimes modified using
the \fIproc\fP file system, and the
.BR sysctl (2)
-system call. Presently, there are subdirectories
+system call.
+Presently, there are subdirectories
.IR abi ", " debug ", " dev ", " fs ", " kernel ", " net ", " proc ", "
.IR rxrpc ", " sunrpc " and " vm
that each contain more files and subdirectories.
This contains the subdirectories
.IR binfmt_misc ", " inotify ", and " mqueue ,
and files
-.IR dentry-state ", " dir-notify-enable ", " dquot-nr ", " file-max ", "
-.IR file-nr ", " inode-max ", " inode-nr ", " inode-state ", "
-.IR lease-break-time ", " leases-enable ", "
+.IR dentry-state ", " dir-notify-enable ", " dquot-nr ", " file-max ", "
+.IR file-nr ", " inode-max ", " inode-nr ", " inode-state ", "
+.IR lease-break-time ", " leases-enable ", "
.IR overflowgid ", " overflowuid ", "
.IR suid_dumpable ", "
.IR super-max ", and " super-nr .
.TP
.I /proc/sys/fs/binfmt_misc
-Documentation for files in this directory can be found
+Documentation for files in this directory can be found
in the kernel sources in
.IR Documentation/binfmt_misc.txt .
.TP
.I /proc/sys/fs/dentry-state
-This file contains six numbers,
-.IR nr_dentry ", " nr_unused ", " age_limit " (age in seconds), "
+This file contains six numbers,
+.IR nr_dentry ", " nr_unused ", " age_limit " (age in seconds), "
want_pages
(pages requested by system) and two dummy values.
nr_dentry seems to be 0 all the time.
imposes an upper limit on the value that may be placed in
.IR file-max .
-If you increase
+If you increase
.IR /proc/sys/fs/file-max ","
be sure to increase
.I /proc/sys/fs/inode-max
to 3-4 times the new
-value of
+value of
.IR /proc/sys/fs/file-max ","
or you will run out of inodes.
.TP
gives the number of files presently opened.
It contains three numbers: The number of allocated
file handles, the number of free file handles and the maximum
-number of file handles. The kernel allocates file handles dynamically,
-but it
-doesn't free them again. If the number of allocated files is close to the
+number of file handles.
+The kernel allocates file handles dynamically, but it
+doesn't free them again.
+If the number of allocated files is close to the
maximum, you should consider increasing the maximum.
When the number of free file handles is
large, you've encountered a peak in your usage of file
handles and you probably don't need to increase the maximum.
.TP
-.I /proc/sys/fs/inode-max
+.I /proc/sys/fs/inode-max
This file contains the maximum number of in-memory inodes.
On some (2.4) systems, it may not be
-present. This value should be 3-4 times larger
+present.
+This value should be 3-4 times larger
than the value in file-max, since stdin, stdout and network sockets also
-need an inode to handle them. When you regularly run
+need an inode to handle them.
+When you regularly run
out of inodes, you need to increase this value.
.TP
.I /proc/sys/fs/inode-nr
.TP
.I /proc/sys/fs/inode-state
This file
-contains seven numbers: nr_inodes, nr_free_inodes, preshrink and four
-dummy
-values.
-nr_inodes is the number of inodes the system has
-allocated. This can be slightly more than inode-max because
+contains seven numbers: nr_inodes, nr_free_inodes, preshrink and four
+dummy values.
+nr_inodes is the number of inodes the system has allocated.
+This can be slightly more than inode-max because
Linux allocates them one page full at a time.
nr_free_inodes represents the number of free inodes.
preshrink is non-zero when the nr_inodes > inode-max and the
more.
.TP
.IR /proc/sys/fs/inotify " (since Linux 2.6.13)"
-This directory contains files
+This directory contains files
.IR max_queued_events ", " max_user_instances ", and " max_user_watches ,
that can be used to limit the amount of kernel memory consumed by the
.I inotify
interface.
-For further details, see
+For further details, see
.BR inotify (7).
.TP
.I /proc/sys/fs/lease-break-time
A non-zero value enables leases.
.TP
.IR /proc/sys/fs/mqueue " (since Linux 2.6.6)"
-This directory contains files
+This directory contains files
.IR msg_max ", " msgsize_max ", and " queues_max ,
controlling the resources used by POSIX message queues.
See
-.BR mq_overview (7)
+.BR mq_overview (7)
for details.
.TP
.IR /proc/sys/fs/overflowgid " and " /proc/sys/fs/overflowuid
allow you to change the value of the fixed UID and GID.
The default is 65534.
Some filesystems only support 16-bit UIDs and GIDs, although in Linux
-UIDs and GIDs are 32 bits. When one of these filesystems is mounted
+UIDs and GIDs are 32 bits.
+When one of these filesystems is mounted
with writes enabled, any UID or GID that would exceed 65535 is translated
to the overflow value before being written to disk.
.TP
.IR /proc/sys/fs/suid_dumpable " (since Linux 2.6.13)"
.\" The following is based on text from Documentation/sysctl/kernel.txt
-The value in this file determines whether core dump files are
+The value in this file determines whether core dump files are
produced for set-user-ID or otherwise protected/tainted binaries.
Three different integer values can be specified:
.sp
\fI0\ (default)\fP
This provides the traditional (pre-Linux 2.6.13) behaviour.
-A core dump will not be produced for a process which has
+A core dump will not be produced for a process which has
changed credentials (by calling
-.BR seteuid (2),
-.BR setgid (2),
-or similar, or by executing a set-user-ID or set-group-ID program)
+.BR seteuid (2),
+.BR setgid (2),
+or similar, or by executing a set-user-ID or set-group-ID program)
or whose binary does not have read permission enabled.
.sp
\fI1\ ("debug")\fP
All processes dump core when possible.
-The core dump is owned by the file system user ID of the dumping process
+The core dump is owned by the file system user ID of the dumping process
and no security is applied.
This is intended for system debugging situations only.
Ptrace is unchecked.
.sp
\fI2\ ("suidsafe")\fP
-Any binary which normally would not be dumped (see "0" above)
-is dumped readable by root only.
+Any binary which normally would not be dumped (see "0" above)
+is dumped readable by root only.
This allows the user to remove the core dump file but not to read it.
-For security reasons core dumps in this mode will not overwrite one
+For security reasons core dumps in this mode will not overwrite one
another or other files.
This mode is appropriate when administrators are
attempting to debug problems in a normal environment.
.TP
-.I /proc/sys/fs/super-max
-This file
+.I /proc/sys/fs/super-max
+This file
controls the maximum number of superblocks, and
thus the maximum number of mounted filesystems the kernel
-can have. You only need to increase super-max if you need to
+can have.
+You only need to increase super-max if you need to
mount more filesystems than the current value in super-max
allows you to.
.TP
.I /proc/sys/fs/super-nr
-This file
+This file
contains the number of filesystems currently mounted.
.TP
.I /proc/sys/kernel
.IR acct ", " cad_pid ", " cap-bound ", "
.IR core_pattern ", " core_uses_pid ", "
.IR ctrl-alt-del ", " dentry-state ", " domainname ", "
-.IR hotplug ", " hostname ", "
+.IR hotplug ", " hostname ", "
.IR htab-reclaim " (PowerPC only), "
.IR java-appletviewer " (binfmt_java, obsolete), "
.IR java-interpreter " (binfmt_java, obsolete), " l2cr " (PowerPC only), "
-.IR modprobe ", " msgmax ", " msgmnb ", "
+.IR modprobe ", " msgmax ", " msgmnb ", "
.IR msgmni ", " osrelease ", " ostype ", " overflowgid ", " overflowuid ,
.IR panic ", " panic_on_oops ", " pid_max ", "
.IR powersave-nap " (PowerPC only), " printk ", " pty ", " random ", "
-.IR real-root-dev ", " reboot-cmd " (SPARC only), " rtsig-max ", "
+.IR real-root-dev ", " reboot-cmd " (SPARC only), " rtsig-max ", "
.IR rtsig-nr ", " sem ", " sg-big-buff ", "
.IR shmall ", " shmmax ", " shmmni ", " sysrq ", " tainted ", " threads-max ,
.IR version ", and " zero-paged " (PowerPC only)."
.TP
.I /proc/sys/kernel/acct
-This file
+This file
contains three numbers: highwater, lowwater and frequency.
If BSD-style process accounting is enabled these values control
-its behaviour. If free space on filesystem where the log lives
-goes below lowwater percent accounting suspends. If free space gets
-above highwater percent accounting resumes. Frequency determines
+its behaviour.
+If free space on filesystem where the log lives
+goes below lowwater percent accounting suspends.
+If free space gets
+above highwater percent accounting resumes.
+Frequency determines
how often the kernel checks the amount of free space (value is in
-seconds). Default values are 4, 2 and 30.
+seconds).
+Default values are 4, 2 and 30.
That is, suspend accounting if <= 2% of space is free; resume it
if >= 4% of space is free; consider information about amount of free space
valid for 30 seconds.
.IR "capability bounding set"
(expressed as a signed decimal number).
This set is ANDed against the capabilities permitted to a process
-during
+during
.BR exec ().
.TP
.I /proc/sys/kernel/core_pattern
Note, however, that the classic darkstar.frop.org has the
hostname "darkstar" and DNS (Internet Domain Name Server)
domainname "frop.org", not to be confused with the NIS (Network
-Information Service) or YP (Yellow Pages) domainname. These two
-domain names are in general different. For a detailed discussion
+Information Service) or YP (Yellow Pages) domainname.
+These two
+domain names are in general different.
+For a detailed discussion
see the
.BR hostname (1)
man page.
.I /proc/sys/kernel/l2cr
(PowerPC only) This file
contains a flag that controls the L2 cache of G3 processor
-boards. If 0, the cache is disabled. Enabled if non-zero.
+boards.
+If 0, the cache is disabled.
+Enabled if non-zero.
.TP
.I /proc/sys/kernel/modprobe
This file
.IR panic_timeout .
If this is zero, the kernel will loop on a panic; if non-zero
it indicates that the kernel should autoreboot after this number
-of seconds. When you use the
+of seconds.
+When you use the
software watchdog device driver, the recommended setting is 60.
.TP
.I /proc/sys/kernel/panic_on_oops
-This file (new in Linux 2.5) controls the kernel's behaviour when an oops
-or
-BUG is encountered. If this file contains 0, then the system
-tries to continue operation. If it contains 1, then the system
+This file (new in Linux 2.5) controls the kernel's behaviour when an oops
+or BUG is encountered.
+If this file contains 0, then the system
+tries to continue operation.
+If it contains 1, then the system
delays a few seconds (to give klogd time to record the oops output)
-and then panics.
+and then panics.
If the
.I /proc/sys/kernel/panic
file is also non-zero then the machine will be rebooted.
.TP
.I /proc/sys/kernel/pid_max
-This file
+This file
(new in Linux 2.5)
specifies the value at which PIDs wrap around
(i.e., the value in this file is one greater than the maximum PID).
The default value for this file, 32768,
results in the same range of PIDs as on earlier kernels.
-On 32-bit platforms, 32768 is the maximum value for
+On 32-bit platforms, 32768 is the maximum value for
.IR pid_max .
-On 64-bit systems,
+On 64-bit systems,
.I pid_max
can be set to any value up to 2^22
(PID_MAX_LIMIT, approximately 4 million).
-.\" Prior to 2.6.10, pid_max could also be raised above 32768 on 32-bit
+.\" Prior to 2.6.10, pid_max could also be raised above 32768 on 32-bit
.\" platforms, but this broke /proc/PID
.\" See http://marc.theaimsgroup.com/?l=linux-kernel&m=109513010926152&w=2
.TP
.IR /proc/sys/kernel/powersave-nap " (PowerPC only)"
-This file
-contains a flag. If set, Linux-PPC will use the 'nap' mode of
+This file contains a flag.
+If set, Linux-PPC will use the 'nap' mode of
powersaving,
otherwise the 'doze' mode will be used.
.TP
are console_loglevel, default_message_loglevel, minimum_console_level and
default_console_loglevel.
These values influence printk() behavior when printing or
-logging error messages. See
+logging error messages.
+See
.BR syslog (2)
for more info on the different loglevels.
Messages with a higher priority than
default_console_loglevel is the default value for console_loglevel.
.TP
.IR /proc/sys/kernel/pty " (since Linux 2.6.4)"
-This directory
+This directory
contains two files relating to the number of Unix 98
pseudo-terminals (see
.BR pts (4))
This directory
contains various parameters controlling the operation of the file
.IR /dev/random .
-See
+See
.BR random (4)
for further information.
.TP
.TP
.IR /proc/sys/kernel/reboot-cmd " (Sparc only) "
This file seems to be a way to give an argument to the SPARC
-ROM/Flash boot loader. Maybe to tell it what to do after
+ROM/Flash boot loader.
+Maybe to tell it what to do after
rebooting?
.TP
.I /proc/sys/kernel/rtsig-max
-(Only in kernels up to and including 2.6.7; see
+(Only in kernels up to and including 2.6.7; see
.BR setrlimit (2))
This file can be used to tune the maximum number
of POSIX realtime (queued) signals that can be outstanding
.TP
.IR /proc/sys/kernel/sem " (since Linux 2.4)"
This file contains 4 numbers defining limits for System V IPC semaphores.
-These fields are, in order:
+These fields are, in order:
.RS
.IP SEMMSL 8
The maximum semaphores per semaphore set.
.RE
.TP
.I /proc/sys/kernel/sg-big-buff
-This file
+This file
shows the size of the generic SCSI device (sg) buffer.
You can't tune it just yet, but you could change it on
compile time by editing include/scsi/sg.h and changing
-the value of SG_BIG_BUFF. However, there shouldn't be any reason to
-change
-this value.
+the value of SG_BIG_BUFF.
+However, there shouldn't be any reason to change this value.
.TP
.I /proc/sys/kernel/shmall
This file
.I /proc/sys/kernel/shmmax
This file
can be used to query and set the run time limit
-on the maximum (System V IPC) shared memory segment size that can be
+on the maximum (System V IPC) shared memory segment size that can be
created.
-Shared memory segments up to 1Gb are now supported in the
-kernel. This value defaults to SHMMAX.
+Shared memory segments up to 1Gb are now supported in the
+kernel.
+This value defaults to SHMMAX.
.TP
.I /proc/sys/kernel/shmmni
(available in Linux 2.4 and onwards)
.TP
.IR /proc/sys/kernel/zero-paged " (PowerPC only) "
This file
-contains a flag. When enabled (non-zero), Linux-PPC will pre-zero pages in
+contains a flag.
+When enabled (non-zero), Linux-PPC will pre-zero pages in
the idle loop, possibly speeding up get_free_pages.
.TP
.I /proc/sys/net
.TP
.I /proc/sys/sunrpc
This directory supports Sun remote procedure call for network file system
-(NFS). On some systems, it is not present.
+(NFS).
+On some systems, it is not present.
.TP
.I /proc/sys/vm
-This directory contains files for memory management tuning, buffer and
+This directory contains files for memory management tuning, buffer and
cache
management.
.TP
Writing to this file causes the kernel to drop clean caches, dentries and
inodes from memory, causing that memory to become free.
-To free pagecache, use
+To free pagecache, use
.IR "echo 1 > /proc/sys/vm/drop_caches" ;
to free dentries and inodes, use
.IR "echo 2 > /proc/sys/vm/drop_caches" ;
to free pagecache, dentries and inodes, use
.IR "echo 3 > /proc/sys/vm/drop_caches" .
-Because this is a non-destructive operation and dirty objects
+Because this is a non-destructive operation and dirty objects
are not freeable, the
-user should run
+user should run
.BR sync (8)
first.
.TP
the kernel will use the legacy (2.4) layout for all processes.
.TP
.I /proc/sys/vm/overcommit_memory
-This file contains the kernel virtual memory accounting mode. Values are:
+This file contains the kernel virtual memory accounting mode.
+Values are:
.br
0: heuristic overcommit (this is the default)
.br
.IR /proc/sys/vm/overcommit_ratio .
.TP
.I /proc/sys/vm/overcommit_ratio
-See the description of
+See the description of
.IR /proc/sys/vm/overcommit_memory .
.TP
.I /proc/sysvipc
-Subdirectory containing the pseudo-files
+Subdirectory containing the pseudo-files
.IR msg ", " sem " and " shm "."
-These files list the System V Interprocess Communication (IPC) objects
+These files list the System V Interprocess Communication (IPC) objects
(respectively: message queues, semaphores, and shared memory)
that currently exist on the system,
providing similar information to that available via
provides further background on the information shown by these files.
.TP
.I /proc/tty
-Subdirectory containing the pseudo-files and subdirectories for
+Subdirectory containing the pseudo-files and subdirectories for
tty drivers and line disciplines.
.TP
.I /proc/uptime
.TP
.I /proc/version
This string identifies the kernel version that is currently running.
-It includes the contents of /proc/sys/ostype, /proc/sys/osrelease and
-/proc/sys/version. For example:
+It includes the contents of /proc/sys/ostype, /proc/sys/osrelease and
+/proc/sys/version.
+For example:
.nf
.in -2
.ft CW
.I /usr/src/linux/Documentation/filesystems/proc.txt
.SH CAVEATS
Note that many strings (i.e., the environment and command line) are in
-the internal format, with sub-fields terminated by null bytes ('\\0'),
+the internal format, with sub-fields terminated by null bytes ('\\0'),
so you
may find that things are more readable if you use \fIod \-c\fP or \fItr
"\\000" "\\n"\fP to read them.
projects / thirdparty / man-pages.git / blobdiff