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What are the functions of subfiles or subfolders in the Linux proc directory?
- 王林forward
- 2023-05-13 10:49:121448browse
1. Linux /proc Directory Introduction
The Linux kernel provides a mechanism to access the internal data structures of the kernel and change kernel settings at runtime through the /proc file system. The proc file system is a pseudo file system that only exists in memory and does not occupy external memory space. It provides an interface for accessing system kernel data in the form of a file system.
Users and applications can obtain system information through proc and change certain parameters of the kernel. Since system information, such as processes, changes dynamically, when a user or application reads a proc file, the proc file system dynamically reads the required information from the system kernel and submits it. Not all of the files or subfolders listed below may exist on your system, depending on your kernel configuration and loaded modules. In addition, there are three very important directories under /proc: net, scsi and sys. The sys directory is writable and can be used to access or modify kernel parameters, while net and scsi depend on the kernel configuration. For example, if the system does not support scsi, the scsi directory does not exist.
In addition to the ones introduced above, there are also some directories named with numbers, which are process directories. Each process currently running in the system has a corresponding directory under /proc, with the pid number of the process as the directory name. They are the interfaces for reading process information. The self directory is the information interface for reading the process itself, which is a link.
2. The role of sub-files or sub-folders in the /proc directory
/proc/buddyinfo How many blocks are available for each order in each memory area is related to the memory fragmentation problem
/proc/cmdline Parameter information passed to the kernel at startup
/proc/cpuinfo cpu information
/proc/crypto All installed encryption passwords and details used by the kernel
/proc/devices Already Loaded devices and categories
/proc/dma List of isa dma channels registered for use
/proc/execdomains Execution domains currently supported by the Linux kernel
/proc/fb List of frame buffer devices, including number and control Its driver
/proc/filesystems The file system types currently supported by the kernel
/proc/interrupts The number of interrupts per irq in the x86 architecture
/proc/iomem The number of each physical device currently in system memory Mapping
/proc/ioports The registered port range used for the input and output of a device
/proc/kcore represents the physical memory of the system and is stored in core file format. The number of bytes displayed is equal to the ram size plus Up 4kb
/proc/kmsg records the information generated by the kernel, which can be processed through /sbin/klogd or /bin/dmesg
/proc/loadavg The load status based on the status of cpu and io in the past period of time , related to the uptime command
/proc/locks Kernel locked file list
/proc/mdstat Multiple hard drives, raid configuration information (md=multiple disks)
/proc/meminfo Ram usage related information
/proc/misc Drivers registered on other major devices (device number 10)
/proc/modules List of all modules loaded into the kernel
/proc/mounts All mounts used in the system
/proc/mtrr Memory type range registers (mtrrs) used by the system
/proc/partitions Block allocation information in the partition
/proc/pci PCI device list in the system
/proc/slabinfo System All active slab cache information
/proc/stat All cpu activity information
/proc/sysrq-trigger When using the echo command to write this file, the remote root user can execute most system request key commands. Just like executing in local terminal. To write to this file, /proc/sys/kernel/sysrq must not be set to 0. This file is also unreadable by root
/proc/uptime How long the system has been running
/proc/swaps Swap space usage
/proc/version Linux kernel version and gcc version
/proc /bus system bus (bus) information, such as pci/usb, etc.
/proc/driver driver information
/proc/fs file system information
/proc/ide ide device information
/proc/irq Interrupt request device information
/proc/net Network card device information
/proc/scsi scsi device information
/proc/tty tty device information
/proc/net/dev Display network adapter and statistical information
/proc/vmstat Virtual memory statistics
/proc/vmcore Memory image when kernel panics
/proc/diskstats Obtain disk information
/proc/schedstat Kernel scheduler statistics
/ proc/zoneinfo displays the statistical information of the memory space, which is useful for analyzing virtual memory behavior
The following is the information of process n in the /proc directory
/proc/n Process information with pid n
/proc/n /cmdline Process startup command
/proc/n/cwd Link to the current working directory of the process
/proc/n/environ Process environment variable list
/proc/n/exe Link to the execution command file of the process
/proc/n/fd contains all file descriptors related to the process
/proc/n/maps Memory mapping information related to the process
/proc/n/mem refers to the memory held by the process, Unreadable
/proc/n/root Link to the root directory of the process
/proc/n/stat The status of the process
/proc/n/statm The status of the memory used by the process
/proc/ n/status process status information, more readable than stat/statm
/proc/self links to the currently running process
3. Practical operation example
1. Column Export all files under /proc/
yafang@qa:~$ ls /proc/ 1 16819 21242 2180 2494 8768 interrupts partitions 116 16820 21244 2181 2524 885 iomem sched_debug 11740 17901 21245 21810 2525 acpi ioports scsi 11742 17903 21247 21812 3 asound irq self 11743 17904 2131 21813 39 buddyinfo kallsyms slabinfo 13452 18362 21319 21923 4 bus kcore stat 13454 18364 2132 2193 41 cgroups key-users swaps 13455 18365 2139 21933 42 cmdline kmsg sys 149 19451 2142 2209 5 cpuinfo kpagecount sysrq-trigger 150 19453 21572 2212 5330 crypto kpageflags sysvipc 151 19454 21574 2219 596 devices loadavg timer_list 152 2 21575 2243 597 diskstats locks timer_stats 15771 2083 2158 2260 6 dma meminfo tty 15773 2092 21625 2261 617 driver misc uptime 15774 2101 21627 2262 619 execdomains modules version 16232 21112 21628 2263 7 fb mounts vmallocinfo 16234 21115 2165 2264 804 filesystems mtrr vmstat 16235 21116 2167 2265 8765 fs net zoneinfo 16811 2112 2177 2338 8767 ide pagetypeinfo
2. View system information and kernel parameters
yafang@qa:~$ ls /proc/sys debug dev fs kernel net vm[code]
3. 查看网卡设备信息
[code]yafang@qa:~$ ls /proc/net anycast6 ip6_flowlabel netfilter raw6 sockstat6 udplite arp ip6_mr_cache netlink route softnet_stat udplite6 dev ip6_mr_vif netstat rt6_stats stat unix dev_mcast ip_mr_cache packet rt_acct tcp vlan dev_snmp6 ip_mr_vif protocols rt_cache tcp6 wireless if_inet6 ipv6_route psched snmp tr_rif igmp mcfilter ptype snmp6 udp igmp6 mcfilter6 raw sockstat udp6
4. 查看scsi设备信息
yafang@qa:~$ ls /proc/scsi device_info scsi
5. 查看所有加载到内核的模块列表
root@bdsp-a-2-1-2:~# cat /proc/modules bdspboard 8486 2 dspcontrol, live 0xe134c000 dspcontrol 9575 1 clkmon, live 0xe135b000 clkmon 6765 1 - live 0xe136c000 diagint 6635 1 - live 0xe1379000 bdsprio 10775 2 srioif,tsi577, live 0xe9389000 tsi577 17998 1 srioif, live 0xe939e000 srioif 7329 0 - live 0xe93b2000 linux_kernel_bde 54666 1 linux_user_bde, live 0xf1417000 (p) linux_user_bde 17849 0 - live 0xf1427000 (p) root@bdsp-a-2-1-2:~#
6. 查看已经加载的设备并分类
root@bcnmb-a:~# cat /proc/devicescharacter devices: 1 mem 2 pty 3 ttyp 4 /dev/vc/0 4 tty 4 ttys 5 /dev/tty 5 /dev/console 5 /dev/ptmx 7 vcs 10 misc 13 input 89 i2c 90 mtd116 linux-user-bde2117 linux-kernel-bde2126 linux-user-bde127 linux-kernel-bde128 ptm136 pts180 usb189 usb_device245 ext_alarm251 ipmidev252 usb_endpoint253 usbmon254 rtcblock devices: 1 ramdisk 8 sd 31 mtdblock 65 sd 66 sd 67 sd 68 sd 69 sd 70 sd 71 sd128 sd129 sd130 sd131 sd132 sd133 sd134 sd135 sd root@bcnmb-a:~#
7. 查看分区中的块分配信息
root@bdsp-a-2-1-2:~# cat /proc/partitions major minor #blocks name 31 0 512 mtdblock0 31 1 512 mtdblock1 31 2 123904 mtdblock2 31 3 4096 mtdblock3 31 4 1024 mtdblock4 31 5 1024 mtdblock5 31 6 512 mtdblock6 31 7 512 mtdblock7 31 8 123904 mtdblock8 31 9 4096 mtdblock9 31 10 1024 mtdblock10 31 11 1024 mtdblock11 31 12 1048576 mtdblock12 root@bdsp-a-2-1-2:~#
8. 查看linux内核版本和gcc版本
root@bdsp-a-2-1-2:~# cat /proc/version linux version 2.6.34.6-wr4.0.0.0_standard (satomi@charliebrown) (gcc version 4.4.1 (wind river linux sourcery g++ 4.4-291) ) #1 smp preempt fri nov 26 16:07:47 cst 2010 root@bdsp-a-2-1-2:~#
9. /proc/sys/fs/file-max
该文件指定了可以分配的文件句柄的最大数目。如果用户得到的错误消息声明由于打开文件数已经达到了最大值，从而他们不能打开更多文件，则可能需要增加该值。可将这个值设置成有任意多个文件，并且能通过将一个新数字值写入该文件来更改该值。默认设置时4096。
改变内核的参数，用vi编辑或echo参数重定向到文件中。
# cat /proc/sys/fs/file-max 4096 # echo 8192 > /proc/sys/fs/file-max # cat /proc/sys/fs/file-max 8192
如果优化了参数，则可以把它们写成添加到文件rc.local中，使它在系统启动时自动完成修改。
其它例子：
1：[root@gechong proc]# more /proc/cmdline
显示了内核启动的命令行
2：[root@gechong proc]# cat /proc/cpuinfo
显示了cpu信息
3：[root@gechong proc]# cat /proc/devices
显示了字符和块设备的主设备号以及分配到这些设备号的设备名称
4：[root@gechong proc]# cat /proc/dma
显示了驱动程序保留的dma通道和保留它们的驱动程序名称
5：[root@gechong proc]# more /proc/filesystems
显示了可供使用的文件系统类型,一种类型一行
6：[root@gechong proc]# more /proc/interrupts
每一行都有一个保留的中断，内容是：中断号 中断次数 登记中断的驱动程序名称
7：[root@gechong proc]# more /proc/ioports
显示了i/o相关的设备驱动器例如磁盘驱动器、以太网卡、声卡设备等
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