Lines Matching +full:proc +full:- +full:id
1 .. SPDX-License-Identifier: GPL-2.0
4 The /proc Filesystem
8 /proc/sys Terrehon Bowden <terrehon@pacbell.net>, October 7 1999
11 move /proc/sys Shen Feng <shen@cn.fujitsu.com> April 1 2009
24 1.1 Process-Specific Subdirectories
26 1.3 IDE devices in /proc/ide
27 1.4 Networking info in /proc/net
29 1.6 Parallel port info in /proc/parport
30 1.7 TTY info in /proc/tty
31 1.8 Miscellaneous kernel statistics in /proc/stat
36 3 Per-Process Parameters
37 3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj - Adjust the oom-killer
39 3.2 /proc/<pid>/oom_score - Display current oom-killer score
40 3.3 /proc/<pid>/io - Display the IO accounting fields
41 3.4 /proc/<pid>/coredump_filter - Core dump filtering settings
42 3.5 /proc/<pid>/mountinfo - Information about mounts
43 3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
44 3.7 /proc/<pid>/task/<tid>/children - Information about task children
45 3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file
46 3.9 /proc/<pid>/map_files - Information about memory mapped files
47 3.10 /proc/<pid>/timerslack_ns - Task timerslack value
48 3.11 /proc/<pid>/patch_state - Livepatch patch operation state
49 3.12 /proc/<pid>/arch_status - Task architecture specific information
50 3.13 /proc/<pid>/fd - List of symlinks to open files
61 ------------------------
65 /proc file system and we've used many freely available sources to write these
69 we know, it is the first 'all-in-one' document about the /proc file system. It
72 It also only covers IPv4 networking, not IPv6 nor other protocols - sorry. But
88 https://www.kernel.org/doc/html/latest/filesystems/proc.html
91 mailing list at linux-kernel@vger.kernel.org and/or try to reach me at
95 ---------------
105 ---------------
106 * Investigating the properties of the pseudo file system /proc and its
108 * Examining /proc's structure
112 ------------------------------------------------------------------------------
114 The proc file system acts as an interface to internal data structures in the
118 First, we'll take a look at the read-only parts of /proc. In Chapter 2, we
119 show you how you can use /proc/sys to change settings.
121 1.1 Process-Specific Subdirectories
122 -----------------------------------
124 The directory /proc contains (among other things) one subdirectory for each
125 process running on the system, which is named after the process ID (PID).
128 subdirectory has the entries listed in Table 1-1.
130 Note that an open file descriptor to /proc/<pid> or to any of its
133 open /proc/<pid> file descriptors corresponding to dead processes
135 also assigned the process ID <pid>. Instead, operations on these FDs
138 .. table:: Table 1-1: Process specific entries in /proc
157 symbol the task is blocked in - or "0" if not blocked.
169 read the file /proc/PID/status::
171 >cat /proc/self/status
220 the ps command. In fact, ps uses the proc file system to obtain its
222 file /proc/PID/status. It fields are described in table 1-2.
225 memory usage. Its seven fields are explained in Table 1-3. The stat file
227 explained in Table 1-4.
233 snapshot of a moment, you can see /proc/<pid>/smaps file and scan page table.
236 .. table:: Table 1-2: Contents of the status fields (as of 4.19)
246 Tgid thread group ID
247 Ngid NUMA group ID (0 if none)
248 Pid process id
249 PPid process id of the parent process
256 NStgid descendant namespace thread group ID hierarchy
257 NSpid descendant namespace process ID hierarchy
258 NSpgid descendant namespace process group ID hierarchy
259 NSsid descendant namespace session ID hierarchy
310 .. table:: Table 1-3: Contents of the statm fields (as of 2.6.8-rc3)
328 .. table:: Table 1-4: Contents of the stat fields (as of 2.6.30-rc7)
333 pid process id
337 ppid process id of the parent process
339 sid session id
369 use /proc/PID/wchan instead)
390 The /proc/PID/maps file contains the currently mapped memory regions and
397 08048000-08049000 r-xp 00000000 03:00 8312 /opt/test
398 08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test
399 0804a000-0806b000 rw-p 00000000 00:00 0 [heap]
400 a7cb1000-a7cb2000 ---p 00000000 00:00 0
401 a7cb2000-a7eb2000 rw-p 00000000 00:00 0
402 a7eb2000-a7eb3000 ---p 00000000 00:00 0
403 a7eb3000-a7ed5000 rw-p 00000000 00:00 0
404 a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6
405 a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6
406 a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6
407 a800b000-a800e000 rw-p 00000000 00:00 0
408 a800e000-a8022000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0
409 a8022000-a8023000 r--p 00013000 03:00 14462 /lib/libpthread.so.0
410 a8023000-a8024000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0
411 a8024000-a8027000 rw-p 00000000 00:00 0
412 a8027000-a8043000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2
413 a8043000-a8044000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2
414 a8044000-a8045000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2
415 aff35000-aff4a000 rw-p 00000000 00:00 0 [stack]
416 ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso]
446 Starting with 6.11 kernel, /proc/PID/maps provides an alternative
447 ioctl()-based API that gives ability to flexibly and efficiently query and
455 The /proc/PID/smaps is an extension based on maps, showing the memory
459 08048000-080bc000 r-xp 00000000 03:02 13130 /bin/bash
488 mapping in /proc/PID/maps. Following lines show the size of the mapping
514 "KSM" reports how many of the pages are KSM pages. Note that KSM-placed zeropages
532 "Swap" shows how much would-be-anonymous memory is also used, but out on swap.
535 replaced by copy-on-write) part of the underlying shmem object out on swap.
581 uw userfaultfd wr-protect tracking
588 be vanished or the reverse -- new added. Interpretation of their meaning
595 Note: reading /proc/PID/maps or /proc/PID/smaps is inherently racy (consistent
607 The /proc/PID/smaps_rollup file includes the same fields as /proc/PID/smaps,
611 - Pss_Anon
612 - Pss_File
613 - Pss_Shmem
621 The /proc/PID/clear_refs is used to reset the PG_Referenced and ACCESSED/YOUNG
623 soft-dirty bit on pte (see Documentation/admin-guide/mm/soft-dirty.rst
627 > echo 1 > /proc/PID/clear_refs
631 > echo 2 > /proc/PID/clear_refs
635 > echo 3 > /proc/PID/clear_refs
637 To clear the soft-dirty bit::
639 > echo 4 > /proc/PID/clear_refs
644 > echo 5 > /proc/PID/clear_refs
646 Any other value written to /proc/PID/clear_refs will have no effect.
648 The /proc/pid/pagemap gives the PFN, which can be used to find the pageflags
649 using /proc/kpageflags and number of times a page is mapped using
650 /proc/kpagecount. For detailed explanation, see
651 Documentation/admin-guide/mm/pagemap.rst.
653 The /proc/pid/numa_maps is an extension based on maps, showing the memory
662 3206000000 default file=/lib64/ld-2.12.so mapped=26 mapmax=6 N0=24 N3=2 kernelpagesize_kB=4
663 320621f000 default file=/lib64/ld-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4
664 3206220000 default file=/lib64/ld-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4
666 …3206800000 default file=/lib64/libc-2.12.so mapped=59 mapmax=21 active=55 N0=41 N3=18 kernelpagesi…
667 320698b000 default file=/lib64/libc-2.12.so
668 3206b8a000 default file=/lib64/libc-2.12.so anon=2 dirty=2 N3=2 kernelpagesize_kB=4
669 3206b8e000 default file=/lib64/libc-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4
681 "policy" reports the NUMA memory policy set for the mapping (see Documentation/admin-guide/mm/numa_…
688 ---------------
692 /proc and are listed in Table 1-5. Not all of these will be present in your
696 .. table:: Table 1-5: Kernel info in /proc
745 pci Deprecated info of PCI bus (new way -> /proc/bus/pci/,
763 they are used for by looking in the file /proc/interrupts::
765 > cat /proc/interrupts
767 0: 8728810 XT-PIC timer
768 1: 895 XT-PIC keyboard
769 2: 0 XT-PIC cascade
770 3: 531695 XT-PIC aha152x
771 4: 2014133 XT-PIC serial
772 5: 44401 XT-PIC pcnet_cs
773 8: 2 XT-PIC rtc
774 11: 8 XT-PIC i82365
775 12: 182918 XT-PIC PS/2 Mouse
776 13: 1 XT-PIC fpu
777 14: 1232265 XT-PIC ide0
778 15: 7 XT-PIC ide1
784 > cat /proc/interrupts
787 0: 1243498 1214548 IO-APIC-edge timer
788 1: 8949 8958 IO-APIC-edge keyboard
789 2: 0 0 XT-PIC cascade
790 5: 11286 10161 IO-APIC-edge soundblaster
791 8: 1 0 IO-APIC-edge rtc
792 9: 27422 27407 IO-APIC-edge 3c503
793 12: 113645 113873 IO-APIC-edge PS/2 Mouse
794 13: 0 0 XT-PIC fpu
795 14: 22491 24012 IO-APIC-edge ide0
796 15: 2183 2415 IO-APIC-edge ide1
797 17: 30564 30414 IO-APIC-level eth0
798 18: 177 164 IO-APIC-level bttv
808 ERR is incremented in the case of errors in the IO-APIC bus (the bus that
810 the IO-APIC automatically retry the transmission, so it should not be a big
811 problem, but you should read the SMP-FAQ.
813 In 2.6.2* /proc/interrupts was expanded again. This time the goal was for
814 /proc/interrupts to display every IRQ vector in use by the system, not
845 Of some interest is the introduction of the /proc/irq directory to 2.4.
853 > ls /proc/irq/
856 > ls /proc/irq/0/
862 > echo 1 > /proc/irq/10/smp_affinity
869 > cat /proc/irq/0/smp_affinity
875 > cat /proc/irq/0/smp_affinity_list
876 1024-1031
878 The default_smp_affinity mask applies to all non-active IRQs, which are the
880 /proc/irq/[0-9]* directory.
889 The way IRQs are routed is handled by the IO-APIC, and it's Round Robin
892 best choice for almost everyone. [Note this applies only to those IO-APIC's
895 There are three more important subdirectories in /proc: net, scsi, and sys.
908 > cat /proc/buddyinfo
927 > cat /proc/pagetypeinfo
950 X86-64. By keeping pages grouped based on their ability to move, the kernel
951 can reclaim pages within a page block to satisfy a high-order allocation.
955 by migrate-type and finishes with details on how many page blocks of each
981 > tail -n +3 /proc/allocinfo | sort -rn
986 13377536 234 block/blk-mq.c:3421 func:blk_mq_alloc_rqs
1005 /proc/net/sockstat for TCP memory allocations.
1011 > cat /proc/meminfo
1089 In-memory cache for files read from the disk (the
1133 Non-file backed pages mapped into userspace page tables
1143 in-kernel data structures cache
1171 CommitLimit = ([total RAM pages] - [total huge TLB pages]) *
1179 in mm/overcommit-accounting.
1214 Non-file backed huge pages mapped into userspace page tables
1230 See Documentation/admin-guide/mm/hugetlbpage.rst.
1257 > cat /proc/vmallocinfo
1258 0xffffc20000000000-0xffffc20000201000 2101248 alloc_large_system_hash+0x204 ...
1260 0xffffc20000201000-0xffffc20000302000 1052672 alloc_large_system_hash+0x204 ...
1262 0xffffc20000302000-0xffffc20000304000 8192 acpi_tb_verify_table+0x21/0x4f...
1264 0xffffc20000304000-0xffffc20000307000 12288 acpi_tb_verify_table+0x21/0x4f...
1266 0xffffc2000031d000-0xffffc2000031f000 8192 init_vdso_vars+0x112/0x210
1267 0xffffc2000031f000-0xffffc2000032b000 49152 cramfs_uncompress_init+0x2e ...
1269 0xffffc2000033a000-0xffffc2000033d000 12288 sys_swapon+0x640/0xac0 ...
1271 0xffffc20000347000-0xffffc2000034c000 20480 xt_alloc_table_info+0xfe ...
1273 0xffffffffa0000000-0xffffffffa000f000 61440 sys_init_module+0xc27/0x1d00 ...
1275 0xffffffffa000f000-0xffffffffa0014000 20480 sys_init_module+0xc27/0x1d00 ...
1277 0xffffffffa0014000-0xffffffffa0017000 12288 sys_init_module+0xc27/0x1d00 ...
1279 0xffffffffa0017000-0xffffffffa0022000 45056 sys_init_module+0xc27/0x1d00 ...
1290 > cat /proc/softirqs
1302 1.3 Networking info in /proc/net
1303 --------------------------------
1305 The subdirectory /proc/net follows the usual pattern. Table 1-8 shows the
1307 support this. Table 1-9 lists the files and their meaning.
1310 .. table:: Table 1-8: IPv6 info in /proc/net
1326 .. table:: Table 1-9: Network info in /proc/net
1348 softnet_stat Per-CPU incoming packets queues statistics of online CPUs
1363 > cat /proc/net/dev
1364 Inter-|Receive |[...
1377 example, the bond0 device will have a directory called /proc/net/bond0/.
1383 -------------
1386 subdirectory named after the driver for this adapter in /proc/scsi.
1387 You'll also see a list of all recognized SCSI devices in /proc/scsi::
1389 >cat /proc/scsi/scsi
1391 Host: scsi0 Channel: 00 Id: 00 Lun: 00
1393 Type: Direct-Access ANSI SCSI revision: 03
1394 Host: scsi0 Channel: 00 Id: 06 Lun: 00
1395 Vendor: PIONEER Model: CD-ROM DR-U06S Rev: 1.04
1396 Type: CD-ROM ANSI SCSI revision: 02
1403 AHA-2940 SCSI adapter::
1405 > cat /proc/scsi/aic7xxx/0
1413 SCSI Adapter: Adaptec AHA-294X Ultra SCSI host adapter
1445 1.5 Parallel port info in /proc/parport
1446 ---------------------------------------
1448 The directory /proc/parport contains information about the parallel ports of
1452 These directories contain the four files shown in Table 1-10.
1455 .. table:: Table 1-10: Files in /proc/parport
1460 autoprobe Any IEEE-1284 device ID information that has been acquired.
1470 1.6 TTY info in /proc/tty
1471 -------------------------
1474 directory /proc/tty. You'll find entries for drivers and line disciplines in
1475 this directory, as shown in Table 1-11.
1478 .. table:: Table 1-11: Files in /proc/tty
1489 /proc/tty/drivers::
1491 > cat /proc/tty/drivers
1492 pty_slave /dev/pts 136 0-255 pty:slave
1493 pty_master /dev/ptm 128 0-255 pty:master
1494 pty_slave /dev/ttyp 3 0-255 pty:slave
1495 pty_master /dev/pty 2 0-255 pty:master
1496 serial /dev/cua 5 64-67 serial:callout
1497 serial /dev/ttyS 4 64-67 serial
1502 unknown /dev/tty 4 1-63 console
1505 1.7 Miscellaneous kernel statistics in /proc/stat
1506 -------------------------------------------------
1509 /proc/stat file. All of the numbers reported in this file are aggregates
1512 > cat /proc/stat
1531 - user: normal processes executing in user mode
1532 - nice: niced processes executing in user mode
1533 - system: processes executing in kernel mode
1534 - idle: twiddling thumbs
1535 - iowait: In a word, iowait stands for waiting for I/O to complete. But there
1541 2. In a multi-core CPU, the task waiting for I/O to complete is not running
1543 3. The value of iowait field in /proc/stat will decrease in certain
1546 So, the iowait is not reliable by reading from /proc/stat.
1547 - irq: servicing interrupts
1548 - softirq: servicing softirqs
1549 - steal: involuntary wait
1550 - guest: running a normal guest
1551 - guest_nice: running a niced guest
1581 -------------------------------
1584 /proc/fs/ext4. Each mounted filesystem will have a directory in
1585 /proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or
1586 /proc/fs/ext4/sda9 or /proc/fs/ext4/dm-0). The files in each per-device
1587 directory are shown in Table 1-12, below.
1589 .. table:: Table 1-12: Files in /proc/fs/ext4/<devname>
1596 1.9 /proc/consoles
1597 -------------------
1601 /dev/console, you may simply look into the file /proc/consoles::
1603 > cat /proc/consoles
1604 tty0 -WU (ECp) 4:7
1605 ttyS0 -W- (Ep) 4:64
1609 +--------------------+-------------------------------------------------------+
1615 +--------------------+-------------------------------------------------------+
1622 +--------------------+-------------------------------------------------------+
1625 +--------------------+-------------------------------------------------------+
1628 -------
1630 The /proc file system serves information about the running system. It not only
1634 The directory structure of /proc reflects the types of information and makes
1641 ---------------
1643 * Modifying kernel parameters by writing into files found in /proc/sys
1645 * Review of the /proc/sys file tree
1647 ------------------------------------------------------------------------------
1649 A very interesting part of /proc is the directory /proc/sys. This is not only
1661 The files in /proc/sys can be used to fine tune and monitor miscellaneous and
1665 very careful when writing to any of these files. The entries in /proc may
1671 Please see: Documentation/admin-guide/sysctl/ directory for descriptions of
1675 -------
1679 /proc/sys tree can not only be read, but also modified. You can use the echo
1684 Chapter 3: Per-process Parameters
1687 3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj- Adjust the oom-killer score
1688 --------------------------------------------------------------------------------
1709 The value of /proc/<pid>/oom_score_adj is added to the badness score before it
1710 is used to determine which task to kill. Acceptable values range from -1000
1713 task or completely disabling it. The lowest possible value, -1000, is
1718 consider for each task. Setting a /proc/<pid>/oom_score_adj value of +500, for
1721 50% more memory. A value of -500, on the other hand, would be roughly
1725 For backwards compatibility with previous kernels, /proc/<pid>/oom_adj may also
1726 be used to tune the badness score. Its acceptable values range from -16
1727 (OOM_ADJUST_MIN) to +15 (OOM_ADJUST_MAX) and a special value of -17
1729 scaled linearly with /proc/<pid>/oom_score_adj.
1731 The value of /proc/<pid>/oom_score_adj may be reduced no lower than the last
1736 3.2 /proc/<pid>/oom_score - Display current oom-killer score
1737 -------------------------------------------------------------
1739 This file can be used to check the current score used by the oom-killer for
1740 any given <pid>. Use it together with /proc/<pid>/oom_score_adj to tune which
1741 process should be killed in an out-of-memory situation.
1747 3.3 /proc/<pid>/io - Display the IO accounting fields
1748 -------------------------------------------------------
1760 test:/tmp # cat /proc/3828/io
1814 accurate for block-backed filesystems. <please add status regarding NFS and
1823 the storage layer. This is done at page-dirtying time.
1842 At its current implementation state, this is a bit racy on 32-bit machines:
1843 if process A reads process B's /proc/pid/io while process B is updating one
1844 of those 64-bit counters, process A could see an intermediate result.
1850 3.4 /proc/<pid>/coredump_filter - Core dump filtering settings
1851 ---------------------------------------------------------------
1855 Conversely, sometimes we want to save file-backed memory segments into a core
1858 /proc/<pid>/coredump_filter allows you to customize which memory segments
1865 - (bit 0) anonymous private memory
1866 - (bit 1) anonymous shared memory
1867 - (bit 2) file-backed private memory
1868 - (bit 3) file-backed shared memory
1869 - (bit 4) ELF header pages in file-backed private memory areas (it is
1871 - (bit 5) hugetlb private memory
1872 - (bit 6) hugetlb shared memory
1873 - (bit 7) DAX private memory
1874 - (bit 8) DAX shared memory
1879 Note that bits 0-4 don't affect hugetlb or DAX memory. hugetlb memory is
1880 only affected by bit 5-6, and DAX is only affected by bits 7-8.
1886 write 0x31 to the process's proc file::
1888 $ echo 0x31 > /proc/1234/coredump_filter
1894 $ echo 0x7 > /proc/self/coredump_filter
1897 3.5 /proc/<pid>/mountinfo - Information about mounts
1898 --------------------------------------------------------
1902 36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
1905 (1) mount ID: unique identifier of the mount (may be reused after umount)
1906 (2) parent ID: ID of parent (or of self for the top of the mount tree)
1937 3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
1938 --------------------------------------------------------
1946 3.7 /proc/<pid>/task/<tid>/children - Information about task children
1947 -------------------------------------------------------------------------
1952 Note the "first level" here -- if a child has its own children they will
1953 not be listed here; one needs to read /proc/<children-pid>/task/<tid>/children
1963 3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file
1964 ---------------------------------------------------------------
1966 files have at least four fields -- 'pos', 'flags', 'mnt_id' and 'ino'.
1970 mount ID of the file system containing the opened file [see 3.5
1971 /proc/<pid>/mountinfo for details]. 'ino' represents the inode number of
1997 eventfd-count: 5a
1999 where 'eventfd-count' is hex value of a counter.
2042 …inotify wd:3 ino:9e7e sdev:800013 mask:800afce ignored_mask:0 fhandle-bytes:8 fhandle-type:1 f_han…
2051 fields 'fhandle-bytes', 'fhandle-type' and 'f_handle', all in hex
2065 fanotify flags:10 event-flags:0
2067 …fanotify ino:4f969 sdev:800013 mflags:0 mask:3b ignored_mask:40000000 fhandle-bytes:8 fhandle-type…
2069 where fanotify 'flags' and 'event-flags' are values used in fanotify_init
2115 exp_name: system-heap
2120 3.9 /proc/<pid>/map_files - Information about memory mapped files
2121 ---------------------------------------------------------------------
2125 | lr-------- 1 root root 64 Jan 27 11:24 333c600000-333c620000 -> /usr/lib64/ld-2.18.so
2126 | lr-------- 1 root root 64 Jan 27 11:24 333c81f000-333c820000 -> /usr/lib64/ld-2.18.so
2127 | lr-------- 1 root root 64 Jan 27 11:24 333c820000-333c821000 -> /usr/lib64/ld-2.18.so
2129 | lr-------- 1 root root 64 Jan 27 11:24 35d0421000-35d0422000 -> /usr/lib64/libselinux.so.1
2130 | lr-------- 1 root root 64 Jan 27 11:24 400000-41a000 -> /usr/bin/ls
2133 vm_area_struct::vm_start-vm_area_struct::vm_end.
2136 files in a fast way instead of parsing /proc/<pid>/maps or
2137 /proc/<pid>/smaps, both of which contain many more records. At the same
2142 3.10 /proc/<pid>/timerslack_ns - Task timerslack value
2143 ---------------------------------------------------------
2153 Valid values are from 0 - ULLONG_MAX
2158 3.11 /proc/<pid>/patch_state - Livepatch patch operation state
2159 -----------------------------------------------------------------
2163 A value of '-1' indicates that no patch is in transition.
2175 3.12 /proc/<pid>/arch_status - task architecture specific status
2176 -------------------------------------------------------------------
2185 $ cat /proc/6753/arch_status
2216 A special value of '-1' indicates that no AVX512 usage was recorded, thus
2220 3.13 /proc/<pid>/fd - List of symlinks to open files
2221 -------------------------------------------------------
2225 lr-x------ 1 root root 64 Sep 20 17:53 0 -> /dev/null
2226 l-wx------ 1 root root 64 Sep 20 17:53 1 -> /dev/null
2227 lrwx------ 1 root root 64 Sep 20 17:53 10 -> 'socket:[12539]'
2228 lrwx------ 1 root root 64 Sep 20 17:53 11 -> 'socket:[12540]'
2229 lrwx------ 1 root root 64 Sep 20 17:53 12 -> 'socket:[12542]'
2232 of stat() output for /proc/<pid>/fd for fast access.
2233 -------------------------------------------------------
2240 ---------------------
2245 hidepid= Set /proc/<pid>/ access mode.
2250 hidepid=off or hidepid=0 means classic mode - everybody may access all
2251 /proc/<pid>/ directories (default).
2253 hidepid=noaccess or hidepid=1 means users may not access any /proc/<pid>/
2257 behaviour). As an additional bonus, as /proc/<pid>/cmdline is unaccessible for
2261 hidepid=invisible or hidepid=2 means hidepid=1 plus all /proc/<pid>/ will be
2264 by "kill -0 $PID"), but it hides process' uid and gid, which may be learned by
2265 stat()'ing /proc/<pid>/ otherwise. It greatly complicates an intruder's task of
2271 /proc/<pid>/ directories that the caller can ptrace.
2290 # grep ^proc /proc/mounts
2291 proc /proc proc rw,relatime,hidepid=2 0 0
2293 # strace -e mount mount -o hidepid=1 -t proc proc /tmp/proc
2294 mount("proc", "/tmp/proc", "proc", 0, "hidepid=1") = 0
2297 # grep ^proc /proc/mounts
2298 proc /proc proc rw,relatime,hidepid=2 0 0
2299 proc /tmp/proc proc rw,relatime,hidepid=2 0 0
2304 # mount -o remount,hidepid=1 -t proc proc /tmp/proc
2306 # grep ^proc /proc/mounts
2307 proc /proc proc rw,relatime,hidepid=1 0 0
2308 proc /tmp/proc proc rw,relatime,hidepid=1 0 0
2317 # mount -o hidepid=invisible -t proc proc /proc
2318 # mount -o hidepid=noaccess -t proc proc /tmp/proc
2319 # grep ^proc /proc/mounts
2320 proc /proc proc rw,relatime,hidepid=invisible 0 0
2321 proc /tmp/proc proc rw,relatime,hidepid=noaccess 0 0