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| Red Hat Linux 7.3: The Official Red Hat Linux Reference Guide |
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| Prev | Chapter 2. The /proc File System | Next |
Below is a list of some of the more useful virtual files in the
top-level of the /proc directory.
This file provides information about the state of the
Advanced Power Management (APM) system. This
information is used by the apm command.
The output of this file on a system without a battery and constantly
connected to an AC power source looks similar to this:
1.16 1.2 0x03 0x01 0xff 0x80 -1% -1 ? |
Executing apm -v command on these systems results
in something similar to this:
APM BIOS 1.2 (kernel driver 1.16)
AC on-line, no system battery |
For these systems, apm may be able to do little
more than put the machine in standby mode. The apm
command is much more useful on laptops. This is also reflected in their
/proc/apm files. This is the output from a sample
file on a laptop running Linux while plugged into a power outlet:
1.16 1.2 0x03 0x01 0x03 0x09 100% -1 ? |
When the same machine is unplugged from its power source and running
on its own batteries for a few minutes, you will see the contents of
the apm file change:
1.16 1.2 0x03 0x00 0x00 0x01 99% 1792 min |
In this state, the apm command yields readable
information from this data:
APM BIOS 1.2 (kernel driver 1.16)
AC off-line, battery status high: 99% (1 day, 5:52) |
This demonstrates the connection between data located in raw
/proc files and the utilities designed to use
that information for specific purposes.
This file essentially shows the parameters passed to the
kernel at the time it is started. A sample
/proc/cmdline file looks similar to this:
The important data contained in the file breaks down in the
following way:
This file changes based on the type of processor in your
system. The output is fairly easy to understand. A sample file looks
like this:
processor : 0
vendor_id : AuthenticAMD
cpu family : 5
model : 9
model name : AMD-K6(tm) 3D+ Processor
stepping : 1
cpu MHz : 400.919
cache size : 256 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr mce cx8 pge mmx syscall 3dnow k6_mtrr
bogomips : 799.53 |
processor — Provides each
processor with an identifying number. If you only have one
processor, you will only see a 0.
cpu family —
Authoritatively tells you the type of processor you have in
the system. Simply place the number in front of "86" to
calculate the value. This is particularly helpful if you are
wondering about the architecture of an older system (686, 586,
486, or 386). As RPM packages are occasionally compiled for
particular architectures, this value tells you which package
to install on the system.
model name — Gives you
the popular name of the processor, including its project name.
cpu MHz — Shows the
precise speed in megahertz of that particular processor (in thousandths).
cache size — Tells you
the amount of level 2 memory cache available to the processor.
flags — Defines a number
of different qualities about the processor, such as the
presence of a floating point unit (FPU) and the ability to
process MMX instructions.
This file displays the various character and block devices currently
configured for use with the kernel. It does not include modules that
are available but not loaded into the kernel. Below is a sample output
from this virtual file:
Character devices:
1 mem
2 pty
3 ttyp
4 ttyS
5 cua
7 vcs
10 misc
14 sound
29 fb
36 netlink
128 ptm
129 ptm
136 pts
137 pts
162 raw
254 iscsictl
Block devices:
1 ramdisk
2 fd
3 ide0
9 md
22 ide1 |
The output from /proc/devices includes the
major number and name of the device.
Character devices are similar to
block devices, except for two basic
differences.
Block devices have a buffer available, allowing them to order requests
before dealing with them. This is important for devices designed to
store information — such as hard drives — because the
ability to order the information before writing it to the device
allows it to be placed in more efficient order. Character devices do
not require buffering.
The other difference is that block devices can send and receive
information in blocks of a size configured per device. Character
devices send data with no preconfigured size.
For more information about devices see
/usr/src/linux-2.4/Documentation/devices.txt.
This file contains a list of the registered ISA direct memory access
(DMA) channels in use. A sample /proc/dma files
looks like this:
This file lists the execution domains currently supported by the
Linux kernel, along with the range of personalities they support.
Think of execution domains as a kind of
"personality" of a particular operating system. Other binary
formats, such as Solaris, UnixWare, and FreeBSD, can be used with
Linux. By changing the personality of a task running in Linux, a
programmer can change the way the operating system treats particular
system calls from a certain binary. Except for the
PER_LINUX execution domain, they
can be implemented as dynamically loadable modules.
This file contains a list of frame buffer devices, with the frame
buffer device number and the driver that controls it. Typical output
of /proc/fb for systems that contain frame buffer
devices looks similar to this:
This file displays a list of the file system types currently
supported by the kernel. Sample output from a generic kernel's
/proc/filesystems file looks similar to this:
nodev rootfs
nodev bdev
nodev proc
nodev sockfs
nodev tmpfs
nodev shm
nodev pipefs
ext2
nodev ramfs
iso9660
nodev devpts
ext3
nodev autofs
nodev binfmt_misc |
The first column signifies whether the file system is mounted on a
block device. Those beginning with
nodev are not mounted on a
device. The second column lists the name of the file systems supported.
The mount command cycles through these file systems
when one is not specified as an argument.
This file records the number of interrupts per IRQ on the x86
architecture. A standard /proc/interrupts looks
similar to this:
CPU0
0: 80448940 XT-PIC timer
1: 174412 XT-PIC keyboard
2: 0 XT-PIC cascade
8: 1 XT-PIC rtc
10: 410964 XT-PIC eth0
12: 60330 XT-PIC PS/2 Mouse
14: 1314121 XT-PIC ide0
15: 5195422 XT-PIC ide1
NMI: 0
ERR: 0 |
For a multi-processor machine, this file may look slightly
different:
CPU0 CPU1
0: 1366814704 0 XT-PIC timer
1: 128 340 IO-APIC-edge keyboard
2: 0 0 XT-PIC cascade
8: 0 1 IO-APIC-edge rtc
12: 5323 5793 IO-APIC-edge PS/2 Mouse
13: 1 0 XT-PIC fpu
16: 11184294 15940594 IO-APIC-level Intel EtherExpress Pro 10/100 Ethernet
20: 8450043 11120093 IO-APIC-level megaraid
30: 10432 10722 IO-APIC-level aic7xxx
31: 23 22 IO-APIC-level aic7xxx
NMI: 0
ERR: 0 |
The first column refers to the IRQ number. Each CPU in the system has
its own column and its own number of interrupts per IRQ. The next
column tells you the type of interrupt, and the last column contains
the name of the device that is located at that IRQ.
Each of the types of interrupts seen in this file, which are
architecture-specific, mean something a little different. For x86
machines, the following values are common:
XT-PIC — The old AT
computer interrupts.
IO-APIC-edge — The
voltage signal on this interrupt transitions from low to high,
creating an edge, where the interrupt
occurs and is only signaled once. This kind of interrupt, as well
as the IO-APIC-level interrupt,
are only seen on systems with processors from the 586 family and
higher.
IO-APIC-level — Generates
interrupts when its voltage signal goes high until the signal goes
low again.
This file shows you the current map of the system's memory for its
various devices:
00000000-0009fbff : System RAM
0009fc00-0009ffff : reserved
000a0000-000bffff : Video RAM area
000c0000-000c7fff : Video ROM
000f0000-000fffff : System ROM
00100000-07ffffff : System RAM
00100000-00291ba8 : Kernel code
00291ba9-002e09cb : Kernel data
e0000000-e3ffffff : VIA Technologies, Inc. VT82C597 [Apollo VP3]
e4000000-e7ffffff : PCI Bus #01
e4000000-e4003fff : Matrox Graphics, Inc. MGA G200 AGP
e5000000-e57fffff : Matrox Graphics, Inc. MGA G200 AGP
e8000000-e8ffffff : PCI Bus #01
e8000000-e8ffffff : Matrox Graphics, Inc. MGA G200 AGP
ea000000-ea00007f : Digital Equipment Corporation DECchip 21140 [FasterNet]
ea000000-ea00007f : tulip
ffff0000-ffffffff : reserved |
The first column displays the memory registers used by each of the
different types of memory. The second column tells the kind of
memory located within those registers. In particular, this column
will even tell you which memory registers are used by the kernel
within the system RAM or, if you have multiple Ethernet ports on
your NIC, the memory registers assigned for each port.
In a way similar to /proc/iomem,
/proc/ioports provides a list of currently
registered port regions used for input or output communication with
a device. This file can be quite long, with a beginning similar to
this:
0000-001f : dma1
0020-003f : pic1
0040-005f : timer
0060-006f : keyboard
0070-007f : rtc
0080-008f : dma page reg
00a0-00bf : pic2
00c0-00df : dma2
00f0-00ff : fpu
0170-0177 : ide1
01f0-01f7 : ide0
02f8-02ff : serial(auto)
0376-0376 : ide1
03c0-03df : vga+
03f6-03f6 : ide0
03f8-03ff : serial(auto)
0cf8-0cff : PCI conf1
d000-dfff : PCI Bus #01
e000-e00f : VIA Technologies, Inc. Bus Master IDE
e000-e007 : ide0
e008-e00f : ide1
e800-e87f : Digital Equipment Corporation DECchip 21140 [FasterNet]
e800-e87f : tulip |
The first column gives the actual IO port address range reserved for
the device listed in the second column.
This file lists Plug and Play (PnP) cards in
ISA slots on the system. This is most often seen with sound cards but
may include any number of devices. A /proc/isapnp
file with Soundblaster entry in it looks similar to this:
Card 1 'CTL0070:Creative ViBRA16C PnP' PnP version 1.0 Product version 1.0
Logical device 0 'CTL0001:Audio'
Device is not active
Active port 0x220,0x330,0x388
Active IRQ 5 [0x2]
Active DMA 1,5
Resources 0
Priority preferred
Port 0x220-0x220, align 0x0, size 0x10, 16-bit address decoding
Port 0x330-0x330, align 0x0, size 0x2, 16-bit address decoding
Port 0x388-0x3f8, align 0x0, size 0x4, 16-bit address decoding
IRQ 5 High-Edge
DMA 1 8-bit byte-count compatible
DMA 5 16-bit word-count compatible
Alternate resources 0:1
Priority acceptable
Port 0x220-0x280, align 0x1f, size 0x10, 16-bit address decoding
Port 0x300-0x330, align 0x2f, size 0x2, 16-bit address decoding
Port 0x388-0x3f8, align 0x0, size 0x4, 16-bit address decoding
IRQ 5,7,2/9,10 High-Edge
DMA 1,3 8-bit byte-count compatible
DMA 5,7 16-bit word-count compatible |
This file can be quite long, depending on the number of devices
displayed here and their requirements or requests for resources.
Each card lists its name, PnP version number, and product version
number. If the device is active and configured, this file will also
reveal the port and IRQ numbers for the device. In addition, to
ensure better compatibility, the card will specify
preferred and
acceptable values for a number of
different parameters. The goal here is to allow the PnP cards to
work around one another and avoid IRQ and port conflicts.
This file represents the physical memory of the system and is stored
in the core file format. Unlike most /proc
files, kcore does display a size. This value is
given in bytes and is equal to the size of physical memory (RAM)
used plus 4KB.
 | Warning |
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| | Be sure to avoid viewing the kcore file in
/proc. The contents of the file will scramble
text output on the terminal. If you accidentally view this file,
press [Ctrl]-[C]
to stop the process then type reset to bring back
the command line prompt.
|
The contents of this file are designed to be examined by a debugger,
such as gdb and is not human readable.
This file is used to hold messages generated by the kernel. These
messages are then picked up by other programs, such as
klogd.
This file holds the kernel exported symbol definitions used by the
modules tools to dynamically link and bind loadable modules.
e003def4 speedo_debug [eepro100]
e003b04c eepro100_init [eepro100]
e00390c0 st_template [st]
e002104c RDINDOOR [megaraid]
e00210a4 callDone [megaraid]
e00226cc megaraid_detect [megaraid] |
The second column refers to the name of a kernel function, and the
first column lists the memory address of that function in the
kernel. The last column reveals the name of the module loaded to
provide that function.
This file provides a look at load average on the processor over time
and additional data used by uptime and other
commands. A sample loadavg file looks similar to
this:
0.20 0.18 0.12 1/80 11206 |
The first three columns measure CPU utilization of the last 1, 5,
and 10 minute periods. The fourth column shows the number of
currently running processes and the total number of processes. The
last column displays the last process ID used.
This files displays the files currently locked by the kernel. The
content of this file contains kernel internal debugging data and can
vary greatly, depending on the use of the system. A sample
locks file of a very lightly loaded system looks
similar to this:
1: FLOCK ADVISORY WRITE 807 03:05:308731 0 EOF c2a260c0 c025aa48 c2a26120
2: POSIX ADVISORY WRITE 708 03:05:308720 0 EOF c2a2611c c2a260c4 c025aa48 |
Each lock is assigned a unique number at the beginning of each
line. The second column refers to the class of lock used, with
FLOCK signifying the older-style
UNIX file locks from a flock system call and
POSIX representing the newer POSIX
locks from the lockf system call.
The third column can have two
values. ADVISORY means that the lock
does not prevent other people from accessing the data; it only
prevents other attempts to lock
it. MANDATORY means that no other
access to the data is permitted while the lock is held. The fourth
column reveals whether the lock is allowing the holder
READ or
WRITE access to the file, and the
fifth column shows the ID of the process holding the lock.
The sixth column shows the ID of the file being locked, in the format
of
MAJOR-DEVICE:MINOR-DEVICE:INODE-NUMBER.
The seventh column shows the start and end of the file's locked
region. The remaining columns point to internal kernel data structures
used for specialized debugging and can be ignored.
This file contains the current information for multiple-disk, RAID
configurations. If your system does not contain such a
configuration, then your mdstat file will look
similar to this:
Personalities :
read_ahead not set
unused devices: <none> |
This file remains in the state above unless you create a software RAID
or md device. In that case, you can use
mdstat to give you a picture of what is currently
happening with your
mdX RAID devices.
The /proc/mdstat file below shows a system with its
md0 configured as a RAID 1 device. It is
currently re-syncing the disks:
Personalities : [linear] [raid1]
read_ahead 1024 sectors
md0: active raid1 sda2[1] sdb2[0] 9940 blocks [2/2] [UU] resync=1% finish=12.3min
algorithm 2 [3/3] [UUU]
unused devices: <none> |
This is one of the more commonly used /proc
files, as it reports back plenty of valuable information about the
current utilization of RAM on the system. A system with 256MB of RAM
and 384MB of swap space might have a /proc/meminfo
file similar to this one:
total: used: free: shared: buffers: cached:
Mem: 261709824 253407232 8302592 0 120745984 48689152
Swap: 402997248 8192 402989056
MemTotal: 255576 kB
MemFree: 8108 kB
MemShared: 0 kB
Buffers: 117916 kB
Cached: 47548 kB
Active: 135300 kB
Inact_dirty: 29276 kB
Inact_clean: 888 kB
Inact_target: 0 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 255576 kB
LowFree: 8108 kB
SwapTotal: 393552 kB
SwapFree: 393544 kB |
Much of the information here is used by the free,
top, and ps commands. In fact,
the output of the free command is even similar in
appearance to the contents and structure of
meminfo. By looking directly at
meminfo, more memory details are revealed:
Mem — Displays the
current state of physical RAM in the system, including a full breakdown
of total, used, free, shared, buffered, and cached memory
utilization in bytes.
Swap — Displays the
total, used, and free amounts of swap space, in bytes.
MemTotal — Total amount
of physical RAM, in kilobytes.
MemFree — The amount of
physical RAM, in kilobytes, left unused by the system.
MemShared — Unused with
2.4 and higher kernels but left in for compatibility with earlier
kernel versions.
Buffers — The amount of
physical RAM, in kilobytes, used for file buffers.
Cached — The amount of
physical RAM, in kilobytes, used as cache memory.
Active — The total
amount of buffer or page cache memory, in kilobytes, that is in
active use.
Inact_dirty — The total
amount of buffer or cache pages, in kilobytes, that might be free
and available.
Inact_clean — The total
amount of buffer or cache pages in kilobytes that are definitely
free and available.
Inact_target — The net
amount of allocations per second, in kilobytes, averaged over
one minute.
HighTotal and
HighFree — The total and
free amount of memory, respectively, that is not directly mapped
into kernel space. The HighTotal
value can vary based on the type of kernel used.
LowTotal and
LowFree — The total and
free amount of memory, respectively, that is directly mapped
into kernel space. The LowTotal
value can vary based on the type of kernel used.
SwapTotal — The total
amount of swap available, in kilobytes.
SwapFree — The total
amount of swap free, in kilobytes.
This file lists miscellaneous drivers registered on the miscellaneous
major device, which is number 10:
135 rtc
1 psaux
134 apm_bios |
The first column is the minor number of each device, and the second
column shows the driver in use.
This file displays a list of all modules that have been loaded by
the system. Its contents will vary based on the configuration and
use of your system, but it should be organized in a similar manner
to this sample /proc/modules file output:
ide-cd 27008 0 (autoclean)
cdrom 28960 0 (autoclean) [ide-cd]
soundcore 4100 0 (autoclean)
agpgart 31072 0 (unused)
binfmt_misc 5956 1
iscsi 32672 0 (unused)
scsi_mod 94424 1 [iscsi]
autofs 10628 0 (autoclean) (unused)
tulip 48608 1
ext3 60352 2
jbd 39192 2 [ext3] |
The first column contains the name of the module. The second column
refers to the memory size of the module, in bytes. The third column
tells you whether the module is currently loaded
(1) or unloaded
(0). The final column states if the
module can unload itself automatically after a period without use
(autoclean) or if it is not being
utilized (unused). Any module with a
line containing a name listed in brackets
([ or
]) tells you that this module depends
upon another module to be present in order to function.
This file provides a quick list of all mounts in use by the system:
rootfs / rootfs rw 0 0
/dev/hda2 / ext3 rw 0 0
/proc /proc proc rw 0 0
/dev/hda1 /boot ext3 rw 0 0
none /dev/pts devpts rw 0 0
none /dev/shm tmpfs rw 0 0
none /proc/sys/fs/binfmt_misc binfmt_misc rw 0 0 |
The output found here is similar to contents of
/etc/mtab, except that
/proc/mount can be more current.
The first column specifies the device that is mounted, with the
second column revealing the mountpoint. The third column tells the
file system type, and the fourth column tells you if it is mounted
read-only (ro) or read-write
(rw). The fifth and sixth columns are
dummy values designed to match the format used in
/etc/mtab.
This file refers to the current Memory Type Range Registers (MTRRs)
in use with the system. If your system's architecture supports
MTRRs, your mtrr might look something like this:
reg00: base=0x00000000 ( 0MB), size= 64MB: write-back, count=1 |
MTRRs are used with Intel P6 family of processors (Pentium Pro and
higher), and they are used to control processor access to memory
ranges. When using a video card on a PCI or AGP bus, a properly
configured mtrr file can increase performance
over 150%.
Most of the time, this value is properly configured for you. For
more information on MTRRs and manually configuring this file, please
see http://web1.linuxhq.com/kernel/v2.3/doc/mtrr.txt.html.
Most of the information here is of little importance to most users,
except for the following columns:
major — The major number
of the device with this partition. The major number in our
example (3) corresponds with
the block device ide0 in
/proc/devices.
minor — The minor number
of the device with this partition. This serves to separate the
partitions into different physical devices and relates to the
number at the end of the name of the partition.
#blocks — Lists the
number of physical disk blocks contained in a particular
partition.
name — The name of the
partition.
This file contains a full listing of every PCI device on your
system. Depending on the number of PCI devices you have,
/proc/pci can get rather long. An example from
this file on a basic system looks similar to this:
Bus 0, device 0, function 0:
Host bridge: Intel Corporation 440BX/ZX - 82443BX/ZX Host bridge (rev 3).
Master Capable. Latency=64.
Prefetchable 32 bit memory at 0xe4000000 [0xe7ffffff].
Bus 0, device 1, function 0:
PCI bridge: Intel Corporation 440BX/ZX - 82443BX/ZX AGP bridge (rev 3).
Master Capable. Latency=64. Min Gnt=128.
Bus 0, device 4, function 0:
ISA bridge: Intel Corporation 82371AB PIIX4 ISA (rev 2).
Bus 0, device 4, function 1:
IDE interface: Intel Corporation 82371AB PIIX4 IDE (rev 1).
Master Capable. Latency=32.
I/O at 0xd800 [0xd80f].
Bus 0, device 4, function 2:
USB Controller: Intel Corporation 82371AB PIIX4 USB (rev 1).
IRQ 5.
Master Capable. Latency=32.
I/O at 0xd400 [0xd41f].
Bus 0, device 4, function 3:
Bridge: Intel Corporation 82371AB PIIX4 ACPI (rev 2).
IRQ 9.
Bus 0, device 9, function 0:
Ethernet controller: Lite-On Communications Inc LNE100TX (rev 33).
IRQ 5.
Master Capable. Latency=32.
I/O at 0xd000 [0xd0ff].
Non-prefetchable 32 bit memory at 0xe3000000 [0xe30000ff].
Bus 0, device 12, function 0:
VGA compatible controller: S3 Inc. ViRGE/DX or /GX (rev 1).
IRQ 11.
Master Capable. Latency=32. Min Gnt=4.Max Lat=255.
Non-prefetchable 32 bit memory at 0xdc000000 [0xdfffffff]. |
This output shows a list of all PCI devices, sorted in the order of
bus, device, and function. Beyond providing the name and version of
the device, this list also gives you detailed
IRQ information so you can quickly look for conflicts.
 | Tip |
|---|
| | To get a more readable version of this informations, type:
|
This file gives information about memory usage on the slab
level. Linux kernels greater than 2.2 use slab
pools to manage memory above the page level. Commonly used
objects have their own slab pools.
The values in this file occur in the following order: cache name,
number of active objects, number of total objects, size of the object,
number of active slabs (blocks) of the objects, total number of slabs
of the objects, and the number of pages per slab.
It should be noted that active in this case
means in use. An active object is one that is in use, and an
active slab is one that contains any used objects.
This file keeps track of a variety of different statistics about the
system since it was last restarted. The contents of
/proc/stat, which can be quite long, begins
something like this:
cpu 1139111 3689 234449 84378914
cpu0 1139111 3689 234449 84378914
page 2675248 8567956
swap 10022 19226
intr 93326523 85756163 174412 0 3 3 0 6 0 1 0 428620 0 60330 0 1368304 5538681
disk_io: (3,0):(1408049,445601,5349480,962448,17135856)
ctxt 27269477
btime 886490134
processes 206458 |
Some of the more popular statistics include:
cpu — Measures the number
of jiffies (1/100 of a second) that
the system has been in user mode, user mode with low priority
(nice), system mode, and the idle task, respectively. The total
for all CPUs is given at the top, and each individual CPU is
listed below with its own statistics.
page — The number of
memory pages the system has written in and out from the disk.
swap — The number of swap
pages the system has brought in and out.
intr — The number of
interrupts the system has experienced.
btime — The boot time,
measured in the number of seconds since January 1, 1970,
otherwise known as the epoch.
This file measures swap space and its utilization. For a system with
only one swap partition, the output of
/proc/swap may look similar to this:
Filename Type Size Used Priority
/dev/hda6 partition 136512 20024 -1 |
While some of this information can be found in other
/proc files, swap provides
for a very quick snapshot of every swap filename, type of swap
space, and total and used sizes (in kilobytes). The priority column
is useful when multiple swap files are in use, and some of them are
preferred over others, such as if they are on faster hard disks. The
lower the priority, the more likely the swap file will be used.
This file contains information about how long the system has on
since its last restart. The output of
/proc/uptime is quite minimal:
The first number tells you the total number of seconds the system
has been up. The second number tells you how much of that time, also
in seconds, the machine has spent idle.
This files tells you the versions of the Linux kernel and
gcc, as well as the version of Red Hat Linux
installed on the system:
Linux version 2.4.18-0.4 (user@foo.redhat.com) (gcc version 2.96 20000731
(Red Hat Linux 7.2 2.96-106)) #1 Wed Mar 13 10:47:08 EST 2002 |
This information is used for a variety of purposes, including the
version data presented when a user logs in.
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Disclaimer: For authoritative source or latest update to this
documentation, please refer to http://www.redhat.com/docs/manuals/linux/ |
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Quotes: Some people know lots more than they tell-- Some don't.
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