Linux in the/proc directory under the detailed documentation (III) __linux

/proc/net subdirectories

The files in this directory describe or modify the behavior of the networking code. You can set or query many of the files in these special files by using the Arp,netstat,route and IPFWADM commands.

Example:
[Root@localhost/]# Ls/proc/net
Anycast6 ip_conntrack mcfilter6 rt6_stats TCP
ARP ip_conntrack_expect netlink Rt_acct tcp6
Dev Ip_mr_cache netstat rt_cache udp
Dev_mcast ip_mr_vif Packet SNMP udp6
DEV_SNMP6 ip_tables_matches psched snmp6 Unix
If_inet6 Ip_tables_names Raw Sockstat Wireless
IGMP ip_tables_targets raw6 Sockstat6
IGMP6 Ipv6_route Route Softnet_stat
Ip6_flowlabel mcfilter RPC Stat
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The following summary describes the features of the files in this directory:

Arp
Dump the statistics of the dev package in the ARP table for each network interface

Dev
Statistics from Network devices

Dev_mcast
List two layer (data link layer) multicast group

Igmp
Joined IGMP multicast groups

NetLink
Information for NetLink socket interface

Netstat
Multiple statistics of network traffic. The first line is the message header with the name of each variable. The next line holds the value of the corresponding variable

Raw
Set interface table for raw sleeve interface

Route
Static routing Table

Rpc
Directory that contains RPC information

Rt_cache
Routing buffering

Snmp
IP/ICMP/TCP/UDP protocol statistics for SNMP agents; alternate rows give field names and values

Sockstat
List the number of tcp/udp/raw/pac/syc_cookies used

Tcp
Socket interface for TCP connections

Udp
Socket interface table for UDP connections

Unix
Nested interface table for UNIX domain sockets
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Example: [Root@localhost/]# Cat/proc/net/route
Iface destination Gateway Flags refcnt use Metric Mask MTU Window Irtt
eth0 0035c2da 00000000 0001 0 0 0 80fffff0
eth0 0000fea9 00000000 0001 0 0 0 0000fff0
Eth0 00000000 0135c2da 0003 0 0 0 00000000
--------------------------------------------------------------------------------


[Root@localhost/]# Cat/proc/net/tcp
SL local_address rem_address St Tx_queue rx_queue tr tm->when retrnsmt uid Timeout inode
0:00000000:8000 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0 9525 1 0dde7500 3000 0 0 2-1
1:00000000:006f 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0 0 9484 1 0dde79e0 3000 0 0 2-1
2:0100007f:0277 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0 0 10049 1 0a8e3a00 3000 0 0 2-1
3:0100007f:14d7 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0 9847 1 0dde7020 3000 0 0 2-1
4:0100007f:0019 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0 0 10286 1 0a8e3520 3000 0 0 2-1
--------------------------------------------------------------------------------
[Root@localhost/]# Cat/proc/net/arp
IP address HW-type Flags HW address Mask Device
218.194.53.1 0x1 0x2 00:0d:bc:78:07:3f * eth0
--------------------------------------------------------------------------------
[Root@localhost/]# CAT/PROC/NET/UDP
SL local_address rem_address St Tx_queue rx_queue tr tm->when retrnsmt uid Timeout inode
0:00000000:8000 00000000:0000 modified 00000000:00000000 00:00000000 00000000 0 9520 2 0b4ef7c0
105:00000000:14e9 00000000:0000 modified 00000000:00000000 00:00000000 00000000 0 10284 2 0b4ef040
111:00000000:006f 00000000:0000 modified 00000000:00000000 00:00000000 00000000 0 0 9483 2 0b4efcc0
116:00000000:02F4 00000000:0000 modified 00000000:00000000 00:00000000 00000000 0 0 9511 2 0b4efa40
119:00000000:0277 00000000:0000 modified 00000000:00000000 00:00000000 00000000 0 0 10050 2 0b4ef2c0

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/PROC/SCSI subdirectories

This directory contains a file that lists all detected SCSI devices, and provides a directory for each controller driver, which provides a subdirectory for each instance of the installed controller.

Example:
Since my machine does not have a SCSI device, GU is temporarily unable to provide an example.
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/proc/sys subdirectories

There are many subdirectories under this directory. Many of the items in this directory can be used to adjust the performance of the system. This directory contains too much information to cover all. Only some of the files in the directory are shown in the example.

Example: [Root@localhost/]# Ls/proc/sys
Debug Dev FS kernel net proc SUNRPC VM
--------------------------------------------------------------------------------
[Root@localhost ~]# ls/proc/sys/fs
Aio-max-nr dentry-state File-nr lease-break-time overflowgid
Aio-nr dir-notify-enable Inode-nr leases-enable overflowuid
Binfmt_misc File-max inode-state Mqueue Quota
--------------------------------------------------------------------------------
[Root@localhost ~]# Ls/proc/sys/kernel
Acct HotPlug Panic SEM
Cad_pid modprobe panic_on_oops Shmall
Cap-bound Msgmax Pid_max Shmmax
Core_pattern MSGMNB print-fatal-signals Shmmni
Core_uses_pid Msgmni PRINTK SysRq
Ctrl-alt-del Ngroups_max Printk_ratelimit Tainted
DomainName Osrelease Printk_ratelimit_burst Threads-max
Exec-shield OSType Pty Vdso
Exec-shield-randomize Overflowgid Random version
Hostname Overflowuid Real-root-dev
--------------------------------------------------------------------------------
[Root@localhost ~]# Ls/proc/sys/net
Core Ethernet IPv4 IPv6 Unix
--------------------------------------------------------------------------------

[Root@localhost sys]# LS/PROC/SYS/VM
Block_dump Laptop_mode Nr_pdflush_threads
Dirty_background_ratio Legacy_va_layout Overcommit_memory
Dirty_expire_centisecs lower_zone_protection Overcommit_ratio
Dirty_ratio Max_map_count Page-cluster
Dirty_writeback_centisecs min_free_kbytes swappiness
Hugetlb_shm_group nr_hugepages Vfs_cache_pressure
--------------------------------------------------------------------------------

[Root@localhost sys]# Ls/proc/sys/net/ipv4
Conf tcp_fack
Icmp_echo_ignore_all Tcp_fin_timeout
Icmp_echo_ignore_broadcasts Tcp_frto
Icmp_ignore_bogus_error_responses TCP_KEEPALIVE_INTVL
Icmp_ratelimit Tcp_keepalive_probes
Icmp_ratemask Tcp_keepalive_time
Igmp_max_memberships tcp_low_latency
IGMP_MAX_MSF Tcp_max_orphans
Inet_peer_gc_maxtime Tcp_max_syn_backlog
Inet_peer_gc_mintime tcp_max_tw_buckets
Inet_peer_maxttl Tcp_mem
Inet_peer_minttl Tcp_moderate_rcvbuf
Inet_peer_threshold Tcp_no_metrics_save
Ip_autoconfig tcp_orphan_retries
Ip_conntrack_max tcp_reordering
Ip_default_ttl Tcp_retrans_collapse
Ip_dynaddr tcp_retries1
Ip_forward Tcp_retries2
Ipfrag_high_thresh tcp_rfc1337
Ipfrag_low_thresh Tcp_rmem
Ipfrag_secret_interval Tcp_sack
Ipfrag_time Tcp_stdurg
Ip_local_port_range tcp_synack_retries
Ip_nonlocal_bind tcp_syncookies
Ip_no_pmtu_disc tcp_syn_retries
Neigh tcp_timestamps
NetFilter Tcp_tso_win_divisor
Route Tcp_tw_recycle
Tcp_abort_on_overflow Tcp_tw_reuse
Tcp_adv_win_scale Tcp_vegas_alpha
Tcp_app_win Tcp_vegas_beta
Tcp_bic tcp_vegas_cong_avoid
Tcp_bic_fast_convergence Tcp_vegas_gamma
Tcp_bic_low_window Tcp_westwood
Tcp_dsack tcp_window_scaling
TCP_ECN Tcp_wmem
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[Root@localhost sys]# Cat/proc/sys/kernel/shmall
2097152
--------------------------------------------------------------------------------
[Root@localhost sys]# Cat/proc/sys/kernel/osrelease
2.6.9-1.667

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Summary: the/proc file system contains a large amount of information about the current system state. Proc's hand pages also have explanatory documents for these documents. Comparing files with the output produced by the tools that analyze the files can be more clearly understood.