| .\" Copyright (C) 1994, 1995 by Daniel Quinlan (quinlan@yggdrasil.com) |
| .\" with networking additions from Alan Cox (A.Cox@swansea.ac.uk) |
| .\" and scsi additions from Michael Neuffer (neuffer@mail.uni-mainz.de) |
| .\" and sysctl additions from Andries Brouwer (aeb@cwi.nl) |
| .\" and System V IPC (as well as various other) additions from |
| .\" Michael Kerrisk <mtk-manpages@gmx.net> |
| .\" |
| .\" This is free documentation; you can redistribute it and/or |
| .\" modify it under the terms of the GNU General Public License as |
| .\" published by the Free Software Foundation; either version 2 of |
| .\" the License, or (at your option) any later version. |
| .\" |
| .\" The GNU General Public License's references to "object code" |
| .\" and "executables" are to be interpreted as the output of any |
| .\" document formatting or typesetting system, including |
| .\" intermediate and printed output. |
| .\" |
| .\" This manual is distributed in the hope that it will be useful, |
| .\" but WITHOUT ANY WARRANTY; without even the implied warranty of |
| .\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| .\" GNU General Public License for more details. |
| .\" |
| .\" You should have received a copy of the GNU General Public |
| .\" License along with this manual; if not, write to the Free |
| .\" Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, |
| .\" USA. |
| .\" |
| .\" Modified 1995-05-17 by faith@cs.unc.edu |
| .\" Minor changes by aeb and Marty Leisner (leisner@sdsp.mc.xerox.com). |
| .\" Modified 1996-04-13, 1996-07-22 by aeb@cwi.nl |
| .\" Modified 2001-12-16 by rwhron@earthlink.net |
| .\" Modified 2002-07-13 by jbelton@shaw.ca |
| .\" Modified 2002-07-22, 2003-05-27, 2004-04-06, 2004-05-25 |
| .\" by Michael Kerrisk <mtk-manpages@gmx.net> |
| .\" 2004-11-17, mtk -- updated notes on /proc/loadavg |
| .\" 2004-12-01, mtk, rtsig-max and rtsig-nr went away in 2.6.8 |
| .\" 2004-12-14, mtk, updated 'statm', and fixed error in order of list |
| .\" 2005-05-12, mtk, updated 'stat' |
| .\" 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 |
| .\" |
| .\" 19 Sep 05: FIXME 2.6.14 has added /proc/PID/smaps (if CONFIG_MMU |
| .\" is enabled) and /proc/PID/numa_maps (if CONFIG_NUMA is enabled); |
| .\" they need to be documented. |
| .\" Info on smaps can be found in the patch-2.6.14-rc1 Changelog |
| .\" and in Documentation/filesystems/proc.txt |
| .\" Info on numa_maps can be found in the patch-2.6.14-rc1 Changelog |
| .\" 19 Sep 05: 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 |
| .\" entry in this man page. |
| .\" 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" |
| .SH NAME |
| proc \- process information pseudo-filesystem |
| |
| .SH DESCRIPTION |
| The |
| .I proc |
| filesystem is a pseudo-filesystem which is used as an interface to |
| kernel data structures. It is commonly mounted at |
| .IR /proc . |
| 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. |
| .PD 1 |
| .TP |
| .I /proc/[number] |
| There is a numerical subdirectory for each running process; the |
| subdirectory is named by the process ID. |
| Each such subdirectory contains the following |
| pseudo-files and directories. |
| .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 |
| read on this file will return 0 characters. |
| 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. |
| To find out the cwd of process 20, for instance, you can do this: |
| |
| .br |
| .nf |
| .ft CW |
| cd /proc/20/cwd; /bin/pwd |
| .fi |
| .ft |
| |
| Note that the |
| .I pwd |
| command is often a shell builtin, and might |
| 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 |
| (typically by calling |
| .BR pthread_exit (3). |
| .TP |
| .I /proc/[number]/environ |
| This file contains the environment for the process. |
| The entries are separated by null bytes ('\\0'), |
| and there may be a null bytes at the end. |
| Thus, to print out the environment of process 1, you would do: |
| |
| .br |
| .nf |
| .ft CW |
| (cat /proc/1/environ; echo) | tr "\\000" "\\n" |
| .fi |
| .ft P |
| |
| (For a reason why one should want to do this, see |
| .BR lilo (8).) |
| .TP |
| .I /proc/[number]/exe |
| Under Linux 2.2 and later, this file is a symbolic link |
| containing the actual path name of the executed command. |
| 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 |
| 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 |
| (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 |
| .BR readlink (2) |
| call on this file under Linux 2.0 returns a string in the format: |
| |
| [device]:inode |
| |
| For example, [0301]:1502 would be inode 1502 on device major 03 (IDE, |
| MFM, etc. drives) minor 01 (first partition on the first drive). |
| |
| .BR find (1) |
| with the \-inum option can be used to locate the file. |
| .TP |
| .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. |
| |
| .\" 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 |
| (typically by calling |
| .BR pthread_exit (3)). |
| |
| Programs that will take a filename, but will not take the standard |
| input, and which write to a file, but will not send their output to |
| standard output, can be effectively foiled this way, assuming that \-i |
| is the flag designating an input file and \-o is the flag designating |
| an output file: |
| .br |
| .nf |
| |
| \f(CWfoobar \-i /proc/self/fd/0 \-o /proc/self/fd/1 ...\fR |
| |
| .fi |
| .br |
| and you have a working filter. |
| .\" The following is not true in my tests (MTK): |
| .\" Note that this will not work for |
| .\" programs that seek on their files, as the files in the fd directory |
| .\" 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 |
| /dev/fd to /proc/self/fd, in fact. |
| .\" FIXME Describe /proc/[number]/loginuid |
| .\" Added in 2.6.11; updating requires CAP_AUDIT_CONTROL |
| .TP |
| .I /proc/[number]/maps |
| A file containing the currently mapped memory regions and their access |
| permissions. |
| |
| The format is: |
| |
| .nf |
| .ft CW |
| .in 8n |
| address perms offset dev inode pathname |
| 08048000-08056000 r-xp 00000000 03:0c 64593 /usr/sbin/gpm |
| 08056000-08058000 rw-p 0000d000 03:0c 64593 /usr/sbin/gpm |
| 08058000-0805b000 rwxp 00000000 00:00 0 |
| 40000000-40013000 r-xp 00000000 03:0c 4165 /lib/ld-2.2.4.so |
| 40013000-40015000 rw-p 00012000 03:0c 4165 /lib/ld-2.2.4.so |
| 4001f000-40135000 r-xp 00000000 03:0c 45494 /lib/libc-2.2.4.so |
| 40135000-4013e000 rw-p 00115000 03:0c 45494 /lib/libc-2.2.4.so |
| 4013e000-40142000 rw-p 00000000 00:00 0 |
| bffff000-c0000000 rwxp 00000000 00:00 0 |
| .ft |
| .fi |
| .in |
| |
| where address is the address space in the process that it occupies, |
| perms is a set of permissions: |
| |
| .nf |
| .in +5 |
| r = read |
| w = write |
| x = execute |
| s = shared |
| p = private (copy on write) |
| .fi |
| .in |
| |
| offset is the offset into the file/whatever, dev is the device |
| (major:minor), and inode is the inode on that device. 0 indicates |
| that no inode is associated with the memory region, as the case would |
| be with bss. |
| |
| Under Linux 2.0 there is no field giving pathname. |
| .TP |
| .I /proc/[number]/mem |
| This file can be used to access the pages of a process's memory through |
| .BR open (2), |
| .BR read (2), |
| and |
| .BR fseek (3). |
| .\" FIXME Describe /proc/[number]/oom_adj |
| .\" Added in 2.6.11; updating requires CAP_SYS_RESOURCE |
| .\" Mention OOM_DISABLE (-17) |
| .\" FIXME Describe /proc/[number]/oom_score |
| .\" Added in 2.6.11; read-only |
| .TP |
| .I /proc/[number]/root |
| 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 |
| 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 |
| (typically by calling |
| .BR pthread_exit (3)). |
| .\" FIXME Describe /proc/[number]/seccomp |
| .\" Added in 2.6.12 |
| .TP |
| .I /proc/[number]/stat |
| 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 |
| .BR scanf (3) |
| format specifiers, are: |
| .RS |
| .TP |
| \fIpid\fP %d |
| 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. |
| .TP |
| \fIstate\fP %c |
| One character from the string "RSDZTW" where R is running, S is |
| sleeping in an interruptible wait, D is waiting in uninterruptible |
| disk sleep, Z is zombie, T is traced or stopped (on a signal), |
| and W is paging. |
| .TP |
| \fIppid\fP %d |
| The PID of the parent. |
| .TP |
| \fIpgrp\fP %d |
| The process group ID of the process. |
| .TP |
| \fIsession\fP %d |
| The session ID of the process. |
| .TP |
| .\" tty_nr needs better explanation. |
| \fItty_nr\fP %d |
| The tty the process uses. |
| .TP |
| \fItpgid\fP %d |
| .\" This field and following, up to and including wchan added 0.99.1 |
| The process group ID of the process which currently owns the tty that |
| the process is connected to. |
| .TP |
| \fIflags\fP %lu |
| 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 |
| \fIminflt\fP %lu |
| The number of minor faults the process has made which have not |
| required loading a memory page from disk. |
| .TP |
| \fIcminflt\fP %lu |
| The number of minor faults that the process's |
| waited-for children have made. |
| .TP |
| \fImajflt\fP %lu |
| The number of major faults the process has made which have |
| required loading a memory page from disk. |
| .TP |
| \fIcmajflt\fP %lu |
| The number of major faults that the process's |
| waited-for children have made. |
| .TP |
| \fIutime\fP %lu |
| The number of jiffies that this process has been scheduled in user |
| mode. |
| .TP |
| \fIstime\fP %lu |
| The number of jiffies that this process has been scheduled in kernel |
| mode. |
| .TP |
| \fIcutime\fP %ld |
| The number of jiffies that this process's |
| waited-for children have been scheduled in user mode. (See also |
| .BR times (2).) |
| .TP |
| \fIcstime\fP %ld |
| The number of jiffies that this process's |
| 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. |
| .TP |
| \fInice\fP %ld |
| The nice value ranges from 19 (nicest) to \-19 (not nice to others). |
| .TP |
| .\" .TP |
| .\" \fIcounter\fP %ld |
| .\" The current maximum size in jiffies of the process's next timeslice, |
| .\" or what is currently left of its current timeslice, if it is the |
| .\" currently running process. |
| .\" .TP |
| .\" \fItimeout\fP %u |
| .\" The time in jiffies of the process's next timeout. |
| \fI0\fP %ld |
| This value is hard coded to 0 as a placeholder for a removed field. |
| .TP |
| \fIitrealvalue\fP %ld |
| The time in jiffies before the next SIGALRM is sent to the process |
| due to an interval timer. |
| .TP |
| \fIstarttime\fP %lu |
| The time in jiffies the process started after system boot. |
| .TP |
| \fIvsize\fP %lu |
| Virtual memory size in bytes. |
| .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 |
| which have not been demand-loaded in, or which are swapped out. |
| .TP |
| \fIrlim\fP %lu |
| Current limit in bytes on the rss of the process (usually |
| 4294967295 on i386). |
| .TP |
| \fIstartcode\fP %lu |
| The address above which program text can run. |
| .TP |
| \fIendcode\fP %lu |
| The address below which program text can run. |
| .TP |
| \fIstartstack\fP %lu |
| The address of the start of the stack. |
| .TP |
| \fIkstkesp\fP %lu |
| The current value of esp (stack pointer), as found in the |
| kernel stack page for the process. |
| .TP |
| \fIkstkeip\fP %lu |
| The current EIP (instruction pointer). |
| .TP |
| \fIsignal\fP %lu |
| The bitmap of pending signals. |
| .TP |
| \fIblocked\fP %lu |
| The bitmap of blocked signals. |
| .TP |
| \fIsigignore\fP %lu |
| The bitmap of ignored signals. |
| .TP |
| \fIsigcatch\fP %lu |
| The bitmap of caught signals. |
| .TP |
| \fIwchan\fP %lu |
| 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 |
| try \fIps \-l\fP to see the WCHAN field in action.) |
| .TP |
| \fInswap\fP %lu |
| Number of pages swapped (not maintained). |
| .TP |
| \fIcnswap\fP %lu |
| Cumulative \fInswap\fP for child processes (not maintained). |
| .TP |
| \fIexit_signal\fP %d |
| Signal to be sent to parent when we die. |
| .TP |
| \fIprocessor\fP %d |
| CPU number last executed on. |
| .TP |
| \fIrt_priority\fP %lu (since kernel 2.5.19) |
| Real-time scheduling priority (see |
| .BR sched_setscheduler (2)). |
| .TP |
| \fIpolicy\fP %lu (since kernel 2.5.19) |
| Scheduling policy (see |
| .BR sched_setscheduler (2)). |
| .RE |
| .TP |
| .I /proc/[number]/statm |
| Provides information about memory status in pages. The columns are: |
| size total program size |
| resident resident set size |
| share shared pages |
| text text (code) |
| lib library |
| data data/stack |
| dt dirty pages (unused in Linux 2.6) |
| .TP |
| .I /proc/[number]/status |
| Provides much of the information in |
| .I /proc/[number]/stat |
| and |
| .I /proc/[number]/statm |
| in a format that's easier for humans to parse. |
| .TP |
| .IR /proc/[number]/task " (since kernel 2.6.0-test6)" |
| This is a directory that contains one subdirectory |
| for each thread in the process. |
| The name of each subdirectory is the numerical thread ID of the |
| thread (see |
| .BR gettid (2)). |
| Within each of these subdirectories, there is a set of |
| files with the same names and contents as under the |
| .I /proc/[number] |
| directories. |
| For attributes that are shared by all threads, the contents for |
| each of the files under the |
| .I task/[thread-ID] |
| subdirectories will be the same as in the corresponding |
| file in the parent |
| .I /proc/[number] |
| directory |
| (e.g., in a multithreaded process, all of the |
| .I task/[thread-ID]/cwd |
| 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 |
| share a working directory). |
| For attributes that are distinct for each thread, |
| 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 |
| files may be different for each thread). |
| |
| .\" 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 |
| (typically by calling |
| .BR pthread_exit (3)). |
| .TP |
| .I /proc/apm |
| Advanced power management version and battery information |
| when CONFIG_APM is defined at kernel compilation time. |
| .TP |
| .I /proc/bus |
| Contains subdirectories for installed busses. |
| .TP |
| .I /proc/bus/pccard |
| Subdirectory for pcmcia devices when CONFIG_PCMCIA is set |
| at kernel compilation time. |
| .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. |
| .TP |
| .I /proc/bus/pci/devices |
| 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 |
| .BR lilo (1). |
| .TP |
| .I /proc/cpuinfo |
| 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 |
| 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. |
| .TP |
| .IR /proc/diskstats " (since Linux 2.5.69)" |
| This file contains disk I/O statistics for each disk device. |
| See the kernel source file |
| .I Documentation/iostats.txt |
| for further information. |
| .TP |
| .I /proc/dma |
| This is a list of the registered \fIISA\fP DMA (direct memory access) |
| channels in use. |
| .TP |
| .I /proc/driver |
| Empty subdirectory. |
| .TP |
| .I /proc/execdomains |
| List of the execution domains (ABI personalities). |
| .TP |
| .I /proc/fb |
| Frame buffer information when CONFIG_FB is defined during kernel |
| compilation. |
| .TP |
| .I /proc/filesystems |
| A text listing of the filesystems which were compiled into the kernel. |
| Incidentally, this is used by |
| .BR mount (1) |
| to cycle through different filesystems when none is specified. |
| .TP |
| .I /proc/fs |
| Empty subdirectory. |
| .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: |
| |
| .nf |
| cache buffer size in KB |
| capacity number of sectors |
| driver driver version |
| geometry physical and logical geometry |
| identify in hexadecimal |
| media media type |
| model manufacturer's model number |
| settings drive settings |
| smart_thresholds in hexadecimal |
| smart_values in hexadecimal |
| .fi |
| |
| 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 |
| 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 |
| are in use. |
| .TP |
| .IR /proc/kallsyms " (since Linux 2.5.71)" |
| This holds the kernel exported symbol definitions used by the |
| .BR modules (X) |
| tools to dynamically link and bind loadable modules. |
| In Linux 2.5.47 and earlier, a similar file with slightly different syntax |
| was named |
| .IR ksyms . |
| .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 |
| kernel (/usr/src/linux/vmlinux) binary, GDB can be used to |
| examine the current state of any kernel data structures. |
| |
| The total length of the file is the size of physical memory (RAM) plus |
| 4KB. |
| .TP |
| .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 |
| 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 |
| which uses the |
| .BR syslog (2) |
| system call facility to log kernel messages. |
| |
| Information in this file is retrieved with the |
| .BR dmesg (8) |
| program. |
| .TP |
| .IR /proc/ksyms " (Linux 1.1.23-2.5.47)" |
| See |
| .IR /proc/kallsyms . |
| .TP |
| .I /proc/loadavg |
| The first three fields in this file are load average figures |
| giving the number of jobs in the run queue (state R) |
| or waiting for disk I/O (state D) averaged over 1, 5, and 15 minutes. |
| They are the same as the load average numbers given by |
| .BR uptime (1) |
| 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); |
| 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. |
| The fifth field is the PID of the process that was most |
| recently created on the system. |
| .TP |
| .I /proc/locks |
| This file shows current file locks |
| .RB ( flock "(2) and " fcntl (2)) |
| and leases |
| .RB ( fcntl (2)). |
| .TP |
| .I /proc/malloc |
| This file is only present if CONFIGDEBUGMALLOC was defined during |
| compilation. |
| .TP |
| .I /proc/meminfo |
| This is used by |
| .BR free (1) |
| to report the amount of free and used memory (both physical and swap) |
| on the system as well as the shared memory and buffers used by the |
| kernel. |
| |
| It is in the same format as |
| .BR free (1), |
| except in bytes rather than KB. |
| .TP |
| .I /proc/mounts |
| 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: |
| after opening the file for reading, a change in this file |
| (i.e., a file system mount or unmount) causes |
| .BR select (2) |
| to mark the file descriptor as readable, and |
| .BR poll (2) |
| and |
| .BR epoll_wait (2) |
| mark the file as having an error condition. |
| .TP |
| .I /proc/modules |
| A text list of the modules that have been loaded by the system. |
| See also |
| .BR lsmod (8). |
| .TP |
| .I /proc/mtrr |
| 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 |
| .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: |
| |
| .nf |
| .ft CW |
| .in 8n |
| IP address HW type Flags HW address Mask Device |
| 192.168.0.50 0x1 0x2 00:50:BF:25:68:F3 * eth0 |
| 192.168.0.250 0x1 0xc 00:00:00:00:00:00 * eth0 |
| .ft |
| .fi |
| .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 |
| 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 |
| collisions |
| and other basic statistics. These are used by the |
| .BR ifconfig (8) |
| program to report device status. The format is: |
| |
| .nf |
| .ft CW |
| .in 1n |
| Inter-| Receive | Transmit |
| face |bytes packets errs drop fifo frame compressed multicast|bytes packets errs drop fifo colls carrier compressed |
| lo: 2776770 11307 0 0 0 0 0 0 2776770 11307 0 0 0 0 0 0 |
| eth0: 1215645 2751 0 0 0 0 0 0 1782404 4324 0 0 0 427 0 0 |
| ppp0: 1622270 5552 1 0 0 0 0 0 354130 5669 0 0 0 0 0 0 |
| tap0: 7714 81 0 0 0 0 0 0 7714 81 0 0 0 0 0 0 |
| .in |
| .ft |
| .fi |
| .\" .TP |
| .\" .I /proc/net/ipx |
| .\" No information. |
| .\" .TP |
| .\" .I /proc/net/ipx_route |
| .\" No information. |
| .TP |
| .I /proc/net/dev_mcast |
| Defined in |
| .IR /usr/src/linux/net/core/dev_mcast.c : |
| .nf |
| .in +5 |
| indx interface_name dmi_u dmi_g dmi_address |
| 2 eth0 1 0 01005e000001 |
| 3 eth1 1 0 01005e000001 |
| 4 eth2 1 0 01005e000001 |
| .in |
| .fi |
| .TP |
| .I /proc/net/igmp |
| Internet Group Management Protocol. Defined in |
| .IR /usr/src/linux/net/core/igmp.c . |
| .TP |
| .I /proc/net/rarp |
| This file uses the same format as the |
| .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 |
| 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 |
| use |
| 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 |
| 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" |
| field holds the effective UID of the creator of the socket. |
| .\" .TP |
| .\" .I /proc/net/route |
| .\" No information, but looks similar to |
| .\" .BR route (8). |
| .TP |
| .I /proc/net/snmp |
| This file holds the ASCII data needed for the IP, ICMP, TCP, and UDP |
| management |
| 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 |
| 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 hold internal information of |
| the kernel socket state and are only useful for debugging. |
| The "uid" |
| 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 |
| 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. |
| The "uid" |
| field holds the effective UID of the creator of the socket. |
| The format is: |
| |
| .nf |
| .ft CW |
| .in 1n |
| sl local_address rem_address st tx_queue rx_queue tr rexmits tm->when uid |
| 1: 01642C89:0201 0C642C89:03FF 01 00000000:00000001 01:000071BA 00000000 0 |
| 1: 00000000:0801 00000000:0000 0A 00000000:00000000 00:00000000 6F000100 0 |
| 1: 00000000:0201 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0 |
| .in |
| .ft |
| .fi |
| .TP |
| .I /proc/net/unix |
| Lists the UNIX domain sockets present within the system and their |
| status. The format is: |
| .nf |
| .sp .5 |
| .ft CW |
| Num RefCount Protocol Flags Type St Path |
| 0: 00000002 00000000 00000000 0001 03 |
| 1: 00000001 00000000 00010000 0001 01 /dev/printer |
| .ft |
| .sp .5 |
| .fi |
| |
| 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 |
| 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 |
| .I /proc/partitions |
| Contains major and minor numbers of each partition as well as number |
| of blocks and partition name. |
| .TP |
| .I /proc/pci |
| This is a listing of all PCI devices found during kernel initialization |
| 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. |
| |
| 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 |
| similar to the one seen during bootup. |
| 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 |
| 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 |
| host-file is named after the number the host was assigned during |
| initialization. |
| |
| 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. |
| .TP |
| .I /proc/self |
| This directory refers to the process accessing the /proc filesystem, |
| and is identical to the /proc directory named by the process ID of the |
| same process. |
| .TP |
| .I /proc/slabinfo |
| Information about kernel caches. The columns are: |
| .nf |
| cache-name |
| num-active-objs |
| total-objs |
| object-size |
| num-active-slabs |
| total-slabs |
| num-pages-per-slab |
| .fi |
| See |
| .BR slabinfo (5) |
| for details. |
| .TP |
| .I /proc/stat |
| kernel/system statistics. Varies with architecture. Common |
| entries include: |
| .RS |
| .TP |
| \fIcpu 3357 0 4313 1362393\fP |
| The amount of time, measured in units of |
| USER_HZ (1/100ths of a second on most architectures), |
| that the system spent in user mode, |
| user mode with low priority (nice), system mode, and the |
| idle task, respectively. |
| .\" FIXME: Actually, the following 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. |
| .sp |
| In Linux 2.6 this line includes three additional columns: |
| .I iowait |
| \- time waiting for I/O to complete (since 2.5.41); |
| .I irq |
| \- 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 fs/proc/proc_misc.c) |
| .\" this is not yet described... |
| .TP |
| \fIpage 5741 1808\fP |
| The number of pages the system paged in and the number that were paged |
| out (from disk). |
| .TP |
| \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 2.6: |
| \fIintr 1462898\fP |
| This line shows counts of interrupts serviced since boot time, |
| for each of the possible system interrupts. |
| The first column is the total of all interrupts serviced; |
| each subsequent column is the total for a particular interrupt. |
| .TP |
| \fIdisk_io: (2,0):(31,30,5764,1,2) (3,0):\fP... |
| (major,minor):(noinfo, read_io_ops, blks_read, write_io_ops, blks_written) |
| .br |
| (Linux 2.4 only) |
| .TP |
| \fIctxt 115315\fP |
| The number of context switches that the system underwent. |
| .TP |
| \fIbtime 769041601\fP |
| boot time, in seconds since the epoch (January 1, 1970). |
| .TP |
| \fIprocesses 86031\fP |
| Number of forks since boot. |
| .TP |
| \fIprocs_running 6\fP |
| Number of processes in runnable state. |
| (Linux 2.5.45 onwards.) |
| .TP |
| \fIprocs_blocked 2\fP |
| Number of processes blocked waiting for I/O to complete. |
| (Linux 2.5.45 onwards.) |
| .RE |
| .TP |
| .I /proc/swaps |
| Swap areas in use. See also |
| .BR swapon (8). |
| .TP |
| .I /proc/sys |
| This directory (present since 1.3.57) contains a number of files |
| and subdirectories corresponding to kernel variables. |
| 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 |
| .IR abi ", " debug ", " dev ", " fs ", " kernel ", " net ", " proc ", " |
| .IR rxrpc ", " sunrpc " and " vm |
| that each contain more files and subdirectories. |
| .TP |
| .I /proc/sys/abi |
| This directory may contain files with application binary information. |
| On some systems, it is not present. |
| .TP |
| .I /proc/sys/debug |
| This directory may be empty. |
| .TP |
| .I /proc/sys/dev |
| This directory contains device specific information (eg dev/cdrom/info). |
| On |
| some systems, it may be empty. |
| .TP |
| .I /proc/sys/fs |
| 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 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 |
| 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), " |
| want_pages |
| (pages requested by system) and two dummy values. |
| nr_dentry seems to be 0 all the time. |
| nr_unused seems to be the number of unused dentries. |
| age_limit is the age in seconds after which dcache entries |
| can be reclaimed when memory is short and want_pages is |
| non-zero when the kernel has called shrink_dcache_pages() and the |
| dcache isn't pruned yet. |
| .TP |
| .I /proc/sys/fs/dir-notify-enable |
| This file can be used to disable or enable the |
| .I dnotify |
| interface described in |
| .BR fcntl (2) |
| on a system-wide basis. |
| A value of 0 in this file disables the interface, |
| and a value of 1 enables it. |
| .TP |
| .I /proc/sys/fs/dquot-max |
| This file shows the maximum number of cached disk quota entries. |
| On some (2.4) systems, it is not present. |
| If the number of free cached disk quota entries is very low and |
| you have some awesome number of simultaneous system users, |
| you might want to raise the limit. |
| .TP |
| .I /proc/sys/fs/dquot-nr |
| This file shows the number of allocated disk quota |
| entries and the number of free disk quota entries. |
| .TP |
| .I /proc/sys/fs/file-max |
| This file defines |
| a system-wide limit on the number of open files for all processes. |
| (See also |
| .BR setrlimit (2), |
| which can be used by a process to set the per-process limit, |
| .BR RLIMIT_NOFILE , |
| on the number of files it may open.) |
| If you get lots |
| of error messages about running out of file handles, |
| try increasing this value: |
| .br |
| |
| .br |
| .nf |
| .ft CW |
| echo 100000 > /proc/sys/fs/file-max |
| .fi |
| .ft |
| |
| The kernel constant |
| .I NR_OPEN |
| imposes an upper limit on the value that may be placed in |
| .IR file-max . |
| |
| 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 |
| .IR /proc/sys/fs/file-max "," |
| or you will run out of inodes. |
| .TP |
| .I /proc/sys/fs/file-nr |
| This (read-only) file |
| 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 |
| |
| 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 |
| 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 |
| than the value in file-max, since stdin, stdout and network sockets also |
| 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 |
| This file contains the first two values from inode-state. |
| .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 |
| 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 |
| system needs to prune the inode list instead of allocating |
| more. |
| .TP |
| .IR /proc/sys/fs/inotify " (since Linux 2.6.13)" |
| 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 |
| .BR inotify (7). |
| .TP |
| .I /proc/sys/fs/lease-break-time |
| This file |
| specifies the grace period that the kernel grants to a process |
| holding a file lease |
| .RB ( fcntl (2)) |
| after it has sent a signal to that process notifying it |
| that another process is waiting to open the file. |
| If the lease holder does not remove or downgrade the lease within |
| this grace period, the kernel forcibly breaks the lease. |
| .TP |
| .I /proc/sys/fs/leases-enable |
| This file can be used to enable or disable file leases |
| .RB ( fcntl (2)) |
| on a system-wide basis. |
| If this file contains the value 0, leases are disabled. |
| A non-zero value enables leases. |
| .TP |
| .IR /proc/sys/fs/mqueue " (since Linux 2.6.6)" |
| This directory contains files |
| .IR msg_max ", " msgsize_max ", and " queues_max , |
| controlling the resources used by POSIX message queues. |
| .TP |
| .I /proc/sys/fs/mqueue/msg_max |
| This file can be used to view and change the ceiling value for the |
| maximum number of messages in a queue. |
| This value acts as a ceiling on the |
| .I attr.mq_maxmsg |
| argument given to |
| .BR mq_open (3). |
| The default and minimum value for |
| .I msg_max |
| is 10; the upper limit is HARD_MAX: |
| .IR "(131072\ /\ sizeof(void\ *))" |
| (32768 on Linux/86). |
| This limit is ignored for privileged processes |
| .RB ( CAP_SYS_RESOURCE ), |
| but the HARD_MAX ceiling is nevertheless imposed. |
| .TP |
| .I /proc/sys/fs/mqueue/msgsize_max |
| This file can be used to view and change the ceiling on the |
| maximum message size. |
| This value acts as a ceiling on the |
| .I attr.mq_msgsize |
| argument given to |
| .BR mq_open (3). |
| The default and minimum value for |
| .I msgsize_max |
| is 8192 bytes; the upper limit is INT_MAX |
| (2147483647 on Linux/86). |
| This limit is ignored for privileged processes |
| .RB ( CAP_SYS_RESOURCE ). |
| .TP |
| .I /proc/sys/fs/mqueue/queues_max |
| This file can be used to view and change the system-wide limit on the |
| number of message queues that can be created. |
| Only privileged processes |
| .RB ( CAP_SYS_RESOURCE ) |
| can create new message queues once this limit has been reached. |
| The default value for |
| .I queues_max |
| is 256; it can be changed to any value in the range 0 to INT_MAX. |
| .TP |
| .IR /proc/sys/fs/overflowgid " and " /proc/sys/fs/overflowuid |
| These files |
| 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 |
| 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 |
| 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 |
| changed credentials (by calling |
| .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 |
| 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. |
| 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 |
| 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 |
| 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 |
| mount more filesystems than the current value in super-max |
| allows you to. |
| .TP |
| .I /proc/sys/fs/super-nr |
| This file |
| contains the number of filesystems currently mounted. |
| .TP |
| .I /proc/sys/kernel |
| This directory contains files |
| .IR acct ", " cad_pid ", " cap-bound ", " |
| .IR core_pattern ", " core_uses_pid ", " |
| .IR ctrl-alt-del ", " dentry-state ", " domainname ", " |
| .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 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 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 |
| 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 |
| how often the kernel checks the amount of free space (value is in |
| 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. |
| .TP |
| .I /proc/sys/kernel/cap-bound |
| This file holds the value of the kernel |
| .IR "capability bounding set" |
| (expressed as a signed decimal number). |
| This set is ANDed against the capabilities permitted to a process |
| during |
| .BR exec (). |
| .TP |
| .I /proc/sys/kernel/core_pattern |
| This file |
| (new in Linux 2.5) provides finer control over the form of |
| a core filename than the obsolete |
| .IR /proc/sys/kernel/core_uses_pid |
| file described below. |
| The name for a core file is controlled by defining a template in |
| .IR /proc/sys/kernel/core_pattern . |
| The template can contain % specifiers which are substituted |
| by the following values when a core file is created: |
| .nf |
| |
| %% A single % character |
| %p PID of dumped process |
| %u real UID of dumped process |
| %g real GID of dumped process |
| %s number of signal causing dump |
| %t time of dump (secs since 0:00h, 1 Jan 1970) |
| %h hostname (same as the 'nodename' |
| returned by \fBuname\fP(2)) |
| %e executable filename |
| |
| .fi |
| A single % at the end of the template is dropped from the |
| core filename, as is the combination of a % followed by any |
| character other than those listed above. |
| All other characters in the template become a literal |
| part of the core filename. |
| The maximum size of the resulting core filename is 64 bytes. |
| The default value in this file is "core". |
| For backward compatibility, if |
| .I /proc/sys/kernel/core_pattern |
| does not include "%p" and |
| .I /proc/sys/kernel/core_uses_pid |
| is non-zero, then .PID will be appended to the core filename. |
| .TP |
| .I /proc/sys/kernel/core_uses_pid |
| This file |
| can be used control the naming of a core dump file on Linux 2.4. |
| If this file contains the value 0, then a core dump file is simply named |
| .IR core . |
| If this file contains a non-zero value, then the core dump file includes |
| the process ID in a name of the form |
| .IR core.PID . |
| .TP |
| .I /proc/sys/kernel/ctrl-alt-del |
| This file |
| controls the handling of Ctrl-Alt-Del from the keyboard. |
| When the value in this file is 0, Ctrl-Alt-Del is trapped and |
| sent to the |
| .BR init (1) |
| program to handle a graceful restart. |
| When the value is > 0, Linux's reaction to a Vulcan |
| Nerve Pinch (tm) will be an immediate reboot, without even |
| syncing its dirty buffers. |
| Note: when a program (like dosemu) has the keyboard in 'raw' |
| mode, the ctrl-alt-del is intercepted by the program before it |
| ever reaches the kernel tty layer, and it's up to the program |
| to decide what to do with it. |
| .TP |
| .I /proc/sys/kernel/hotplug |
| This file |
| contains the path for the hotplug policy agent. |
| The default value in this file "/sbin/hotplug". |
| .TP |
| .IR /proc/sys/kernel/domainname " and " /proc/sys/kernel/hostname |
| can be used to set the NIS/YP domainname and the |
| hostname of your box in exactly the same way as the commands |
| domainname and hostname, i.e.: |
| .br |
| |
| .br |
| # echo "darkstar" > /proc/sys/kernel/hostname |
| .br |
| # echo "mydomain" > /proc/sys/kernel/domainname |
| .br |
| |
| .br |
| has the same effect as |
| .br |
| |
| .br |
| # hostname "darkstar" |
| .br |
| # domainname "mydomain" |
| .br |
| |
| .br |
| 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 |
| see the |
| .BR hostname (1) |
| man page. |
| .TP |
| .I /proc/sys/kernel/htab-reclaim |
| (PowerPC only) If this file is set to a non-zero value, |
| the PowerPC htab |
| (see kernel file Documentation/powerpc/ppc_htab.txt) is pruned |
| each time the system hits the idle loop. |
| .TP |
| .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. |
| .TP |
| .I /proc/sys/kernel/modprobe |
| This file |
| is described by the kernel source file Documentation/kmod.txt. |
| .TP |
| .I /proc/sys/kernel/msgmax |
| This file defines |
| a system-wide limit specifying the maximum number of bytes in |
| a single message written on a System V message queue. |
| .TP |
| .I /proc/sys/kernel/msgmni |
| This file defines the system-wide limit on the number of |
| message queue identifiers. |
| (This file is only present in Linux 2.4 onwards.) |
| .TP |
| .I /proc/sys/kernel/msgmnb |
| This file defines a system-wide parameter used to initialise the |
| .I msg_qbytes |
| setting for subsequently created message queues. |
| The |
| .I msg_qbytes |
| setting specifies the maximum number of bytes that may be written to the |
| message queue. |
| .TP |
| .IR /proc/sys/kernel/ostype " and " /proc/sys/kernel/osrelease |
| These files |
| give substrings of |
| .IR /proc/version . |
| .TP |
| .IR /proc/sys/kernel/overflowgid " and " /proc/sys/kernel/overflowuid |
| These files duplicate the files |
| .I /proc/sys/fs/overflowgid |
| and |
| .IR /proc/sys/fs/overflowuid . |
| .TP |
| .I /proc/sys/kernel/panic |
| gives read/write access to the kernel variable |
| .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 |
| 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 |
| delays a few seconds (to give klogd time to record the oops output) |
| 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 |
| (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 platfroms, 32768 is the maximum value for |
| .IR pid_max . |
| 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 |
| .\" 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 |
| powersaving, |
| otherwise the 'doze' mode will be used. |
| .TP |
| .I /proc/sys/kernel/printk |
| The four values in this file |
| 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 |
| .BR syslog (2) |
| for more info on the different loglevels. |
| Messages with a higher priority than |
| console_loglevel will be printed to the console. |
| Messages without an explicit priority |
| will be printed with priority default_message_level. |
| minimum_console_loglevel is the minimum (highest) value to which |
| console_loglevel can be set. |
| default_console_loglevel is the default value for console_loglevel. |
| .TP |
| .IR /proc/sys/kernel/pty " (since Linux 2.6.4)" |
| This directory |
| contains two files relating to the number of Unix 98 |
| pseudo-terminals (see |
| .BR pts (4)) |
| on the system. |
| .TP |
| .I /proc/sys/kernel/pty/max |
| This file defines the maximum number of pseudo-terminals. |
| .TP |
| .I /proc/sys/kernel/pty/nr |
| This read-only file |
| indicates how many pseudo-terminals are currently in use. |
| .TP |
| .I /proc/sys/kernel/random |
| This directory |
| contains various parameters controlling the operation of the file |
| .IR /dev/random . |
| See |
| .BR random (4) |
| for further information. |
| .TP |
| .I /proc/sys/kernel/real-root-dev |
| This file |
| is documented in the kernel source file Documentation/initrd.txt. |
| .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 |
| rebooting? |
| .TP |
| .I /proc/sys/kernel/rtsig-max |
| (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 |
| in the system. |
| .TP |
| .I /proc/sys/kernel/rtsig-nr |
| (Only in kernels up to and including 2.6.7.) |
| This file shows the number POSIX realtime signals currently queued. |
| .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: |
| .RS |
| .IP SEMMSL 8 |
| The maximum semaphores per semaphore set. |
| .IP SEMMNS 8 |
| A system-wide limit on the number of semaphores in all semaphore sets. |
| .IP SEMOPM 8 |
| The maximum number of operations that may be specified in a |
| .BR semop (2) |
| call. |
| .IP SEMMNI 8 |
| A system-wide limit on the maximum number of semaphore identifiers. |
| .RE |
| .TP |
| .I /proc/sys/kernel/sg-big-buff |
| 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. |
| .TP |
| .I /proc/sys/kernel/shmall |
| This file |
| contains the system-wide limit on the total number of pages of |
| System V shared memory. |
| .TP |
| .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 |
| created. |
| 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) |
| This file |
| specifies the system-wide maximum number of System V shared memory |
| segments that can be created. |
| .TP |
| .I /proc/sys/kernel/version |
| contains a string like: |
| .br |
| |
| .br |
| #5 Wed Feb 25 21:49:24 MET 1998.TP |
| .br |
| |
| .br |
| The '#5' means that |
| this is the fifth kernel built from this source base and the |
| date behind it indicates the time the kernel was built. |
| .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 |
| the idle loop, possibly speeding up get_free_pages. |
| .TP |
| .I /proc/sys/net |
| This directory contains networking stuff. |
| Explanations for some of the files under this directory can be found in |
| .BR tcp (7) |
| and |
| .BR ip (7). |
| .TP |
| .I /proc/sys/proc |
| This directory may be empty. |
| .TP |
| .I /proc/sys/sunrpc |
| This directory supports Sun remote procedure call for network file system |
| (NFS). On some systems, it is not present. |
| .TP |
| .I /proc/sys/vm |
| This directory contains files for memory management tuning, buffer and |
| cache |
| management. |
| .TP |
| .IR /proc/sys/vm/legacy_va_layout " (since Linux 2.6.9)" |
| .\" The following is from Documentation/filesystems/proc.txt |
| If non-zero, this disable the new 32-bit memory-mapping layout; |
| 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: |
| .br |
| 0: heuristic overcommit (this is the default) |
| .br |
| 1: always overcommit, never check |
| .br |
| 2: always check, never overcommit |
| .br |
| In mode 0, calls of |
| .BR mmap (2) |
| with MAP_NORESERVE set are not checked, and the default check is very weak, |
| leading to the risk of getting a process "OOM-killed". |
| Under Linux 2.4 any non-zero value implies mode 1. |
| In mode 2 (available since Linux 2.6), the total virtual address space |
| on the system is limited to (SS + RAM*(r/100)), |
| where SS is the size of the swap space, and RAM |
| is the size of the physical memory, and r is the contents of the file |
| .IR /proc/sys/vm/overcommit_ratio . |
| .TP |
| .I /proc/sys/vm/overcommit_ratio |
| See the description of |
| .IR /proc/sys/vm/overcommit_memory . |
| .TP |
| .I /proc/sysvipc |
| Subdirectory containing the pseudo-files |
| .IR msg ", " sem " and " shm "." |
| 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 |
| .BR ipcs (1). |
| These files have headers and are formatted (one IPC object per line) |
| for easy understanding. |
| .BR ipc (5) |
| provides further background on the information shown by these files. |
| .TP |
| .I /proc/tty |
| Subdirectory containing the pseudo-files and subdirectories for |
| tty drivers and line disciplines. |
| .TP |
| .I /proc/uptime |
| This file contains two numbers: the uptime of the system (seconds), |
| and the amount of time spent in idle process (seconds). |
| .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: |
| .nf |
| .in -2 |
| .ft CW |
| Linux version 1.0.9 (quinlan@phaze) #1 Sat May 14 01:51:54 EDT 1994 |
| .ft |
| .in +2 |
| .fi |
| .TP |
| .IR /proc/vmstat " (since Linux 2.6)" |
| This file displays various virtual memory statistics. |
| |
| .TP |
| .IR /proc/zoneinfo " (since Linux 2.6.13)" |
| This file display information about memory zones. |
| This is useful for analysing virtual memory behaviour. |
| .\" FIXME -- more should be said about /proc/zoneinfo |
| .RE |
| .RE |
| .SH "SEE ALSO" |
| .BR cat (1), |
| .BR find (1), |
| .BR free (1), |
| .BR mount (1), |
| .BR ps (1), |
| .BR tr (1), |
| .BR uptime (1), |
| .BR chroot (2), |
| .BR mmap (2), |
| .BR readlink (2), |
| .BR syslog (2), |
| .BR slabinfo (5), |
| .BR hier (7), |
| .BR arp (8), |
| .BR dmesg (8), |
| .BR hdparm (8), |
| .BR ifconfig (8), |
| .BR init (8), |
| .BR lsmod (8), |
| .BR lspci (8), |
| .BR netstat (8), |
| .BR procinfo (8), |
| .BR route (8) |
| .br |
| .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'), |
| so you |
| may find that things are more readable if you use \fIod \-c\fP or \fItr |
| "\\000" "\\n"\fP to read them. |
| Alternatively, \fIecho `cat <file>`\fP works well. |
| |
| This manual page is incomplete, possibly inaccurate, and is the kind |
| of thing that needs to be updated very often. |
| .SH ACKNOWLEDGEMENTS |
| The material on /proc/sys/fs and /proc/sys/kernel is closely based on |
| kernel source documentation files written by Rik van Riel. |