procfs Directory Reference

15 `procfs` Directory Reference

The following table describes the most useful virtual files and directories under the /proc directory hierarchy. For more information, see the proc(5) manual page.

Table 15-1 Useful Virtual Files and Directories Under the /proc Directory

Virtual File or Directory	Description
`PID` (Directory)	Provides information about the process with the process ID (PID). The directory's owner and group is same as the process's. Useful files under the directory include: `cmdline` Command path. `cwd` Symbolic link to the process's current working directory. `environ` Environment variables. `exe` Symbolic link to the command executable. `fd/N` File descriptors. `maps` Memory maps to executable and library files. `root` Symbolic link to the effective root directory for the process. `stack` The contents of the kernel stack. `status` Run state and memory usage.
`buddyinfo`	Provides information for diagnosing memory fragmentation.
`bus` (directory)	Contains information about the various buses (such as `pci` and `usb`) that are available on the system. You can use commands such as `lspci`, `lspcmcia`, and `lsusb` to display information for such devices.
`cgroups`	Provides information about the resource control groups that are in use on the system.
`cmdline`	Lists parameters passed to the kernel at boot time.
`cpuinfo`	Provides information about the system's CPUs.
`crypto`	Provides information about all installed cryptographic cyphers.
`devices`	Lists the names and major device numbers of all currently configured characters and block devices.
`dma`	Lists the direct memory access (DMA) channels that are currently in use.
`driver` (directory)	Contains information about drivers used by the kernel, such as those for nonvolatile RAM (`nvram`), the real-time clock (`rtc`), and memory allocation for sound (`snd-page-alloc`).
`execdomains`	Lists the execution domains for binaries that the Oracle Linux kernel provides.
`filesystems`	Lists the file system types that the kernel provides. Entries marked with `nodev` aren't in use.
`fs` (directory)	Contains information about mounted file systems, organized by file system type.
`interrupts`	Records the number of interrupts per interrupt request queue (IRQ) for each CPU after system startup.
`iomem`	Lists the system memory map for each physical device.
`ioports`	Lists the range of I/O port addresses that the kernel uses with devices.
`irq` (directory)	Contains information about each IRQ. You can configure the affinity between each IRQ and the system CPUs.
`kcore`	Presents the system's physical memory in `core` file format that you can examine using a debugger such as `crash` or `gdb`. This file isn't human-readable.
`kmsg`	Records kernel-generated messages, which are picked up by programs such as `dmesg`.
`loadavg`	Displays the system load averages (number of queued processes) for the past 1, 5, and 15 minutes, the number of running processes, the total number of processes, and the PID of the process that's running.
`locks`	Displays information about the file locks that the kernel is currently holding on behalf of processes. The information provided includes: lock class (`FLOCK` or `POSIX`) lock type (`ADVISORY` or `MANDATORY`) access type (`READ` or `WRITE`) process ID major device, minor device, and inode numbers bounds of the locked region
`mdstat`	Lists information about multiple-disk RAID devices.
`meminfo`	Reports the system's usage of memory in more detail than is available using the `free` or `top` commands.
`modules`	Displays information about the modules that are currently loaded into the kernel. The `lsmod` command formats and displays the same information, excluding the kernel memory offset of a module.
`mounts`	Lists information about all mounted file systems.
`net` (directory)	Provides information about networking protocol, parameters, and statistics. Each directory and virtual file describes aspects of the configuration of the system's network.
`partitions`	Lists the major and minor device numbers, number of blocks, and name of partitions mounted by the system.
`scsi/device_info`	Provides information about SCSI devices.
`scsi/scsi` and `scsi/sg/*`	Provide information about configured SCSI devices, including vendor, model, channel, ID, and LUN data.
`self`	Symbolic link to the process that's examining `/proc`.
`slabinfo`	Provides detailed information about slab memory usage.
`softirqs`	Displays information about software interrupts (`softirqs`). A `softirq` is similar to a hardware interrupt (`hardirq`) and configures the kernel to perform asynchronous processing that would take too long during a hardware interrupt.
`stat`	Records information about the system from when it was started, including: `cpu` Total CPU time (measured in `jiffies`) spent in user mode, low-priority user mode, system mode, idle, waiting for I/O, handling hardirq events, and handling softirq events. `cpuN` Times for CPU N.
`swaps`	Provides information about swap devices. The units of size and usage are in kilobytes.
`sys` (directory)	Provides information about the system and also enables you to enable, disable, or modify kernel features. You can write new settings to any file that has write permission. See Managing Kernel Parameters at Runtime. The following subdirectory hierarchies of `/proc/sys` contain virtual files, some of whose values you can alter: `dev` Device parameters. `fs` File system parameters. `kernel` Kernel configuration parameters. `net` Networking parameters.
`sysvipc` (directory)	Provides information about the usage of System V Interprocess Communication (IPC) resources for messages (`msg`), semaphores (`sem`), and shared memory (`shm`).
`tty` (directory)	Provides information about the available and currently used terminal devices on the system. The `drivers` virtual file lists the devices that are currently configured.
`vmstat`	Provides information about virtual memory usage.