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172 lines
6.0 KiB
172 lines
6.0 KiB
= procfs !
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Apostolos rootApostolos@swarmlab.io
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// Metadata:
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:description: Intro
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:keywords: procfs
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:data-uri:
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:toc: right
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:toc-title: Πίνακας περιεχομένων
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:toclevels: 4
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:source-highlighter: highlight
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:icons: font
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:sectnums:
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{empty} +
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.procfs
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****
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The proc filesystem (*procfs*) is a special filesystem in Unix-like operating systems that presents information about processes and other system information in a hierarchical file-like structure,
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*providing* a more convenient and *standardized method for dynamically accessing process* data held in the kernel than traditional tracing methods or direct access to kernel memory.
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Typically
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- it is mapped to a mount point named /proc at boot time.
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- The proc file system acts as an interface to internal data structures in the kernel.
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- It can be used to obtain information about the system and to change certain kernel parameters at runtime (sysctl).
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****
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== The /proc Filesystem
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NOTE: The proc filesystem provides a method of communication between *kernel space* and *user space*. For example, the GNU version of the process reporting utility *ps* uses the proc file system to obtain its data, without using any specialized system calls.
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The directory /proc contains (among other things) one subdirectory for each process running on the system, which is named after the process ID (PID).
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The link ‘self’ points to the process reading the file system. Each process subdirectory has the entries listed in: ls /proc/<pid>
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[source,bash]
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----
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cat /proc/meminfo
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MemTotal: 8174328 kB
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MemFree: 6186516 kB
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MemAvailable: 7535332 kB
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Buffers: 146740 kB
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Cached: 1294156 kB
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SwapCached: 0 kB
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Active: 967184 kB
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Inactive: 606252 kB
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Active(anon): 135620 kB
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Inactive(anon): 85064 kB
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Active(file): 831564 kB
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Inactive(file): 521188 kB
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Unevictable: 3652 kB
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Mlocked: 3652 kB
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SwapTotal: 0 kB
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SwapFree: 0 kB
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Dirty: 68 kB
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Writeback: 0 kB
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AnonPages: 136188 kB
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Mapped: 113344 kB
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Shmem: 85724 kB
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Slab: 340236 kB
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SReclaimable: 302048 kB
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SUnreclaim: 38188 kB
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KernelStack: 3792 kB
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PageTables: 4888 kB
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NFS_Unstable: 0 kB
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Bounce: 0 kB
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WritebackTmp: 0 kB
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CommitLimit: 4087164 kB
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Committed_AS: 901432 kB
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VmallocTotal: 34359738367 kB
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VmallocUsed: 0 kB
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VmallocChunk: 0 kB
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HardwareCorrupted: 0 kB
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AnonHugePages: 51200 kB
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CmaTotal: 0 kB
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CmaFree: 0 kB
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...
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----
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.Main entries in /proc
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[options="header,footer"]
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|=======================
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|File|Content
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| /proc/cmdline | – Kernel command line information.
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| /proc/console | – Information about current consoles including tty.
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| /proc/crypto | - a list of available cryptographic modules
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| /proc/devices | – Device drivers currently configured for the running kernel.
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| /proc/diskstats | - giving some information (including device numbers) for each of the logical disk devices
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| /proc/dma | – Info about current DMA channels.
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| /proc/fb | – Framebuffer devices.
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| /proc/filesystems | – Current filesystems supported by the kernel.
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| /proc/interrupts, /proc/iomem, /proc/ioports and the directory /proc/irq | - giving some self-explanatory details about the devices (physical or logical) using the various system resources
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| /proc/iomem | – Current system memory map for devices.
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| /proc/ioports | – Registered port regions for input output communication with device.
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| /proc/loadavg | – System load average.
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| /proc/locks | – Files currently locked by kernel.
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| /proc/meminfo | – Info about system memory (see above example).
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| /proc/misc | – Miscellaneous drivers registered for miscellaneous major device.
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| /proc/modules | - one of the most important files in /proc, containing a list of the kernel modules currently loaded . It gives some indication (not always entirely correct) of dependencies.
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| /proc/mounts | – List of all mounts in use by system.
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| /proc/mounts | - a symlink to self/mounts which contains a list of the currently mounted devices and their mount points (and which file system is in use and what mount options are in use).
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| /proc/net | - a directory containing useful information about the network stack, in particular /proc/net/nf_conntrack, which lists existing network connections (particularly useful for tracking routing when iptables FORWARD is used to redirect network connections)
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| /proc/partitions | – Detailed info about partitions available to the system.
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| /proc/pci | – Information about every PCI device.
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| /proc/stat | – Record or various statistics kept from last reboot.
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| /proc/swap | – Information about swap space.
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| /proc/scsi | - giving information about any devices connected via a SCSI or RAID controller
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| /proc/sysvipc | - containing memory-sharing and inter-process communication (IPC) information.
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| /proc/tty | - containing information about the current terminals; /proc/tty/driver looks to be[original research?] a list of the different types of tty available - each of which is a list of those of each type
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| /proc/uptime | – Uptime information (in seconds).
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| /proc/version | – Kernel version, gcc version, and Linux distribution installed.
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|=======================
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== cpu info
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[source,bash]
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----
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cat /proc/cpuinfo
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processor : 0
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vendor_id : AuthenticAMD
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cpu family : 16
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model : 6
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model name : AMD Athlon(tm) II X2 270 Processor
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stepping : 3
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microcode : 0x10000c8
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cpu MHz : 2000.000
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cache size : 1024 KB
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...
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processor : 1
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vendor_id : AuthenticAMD
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cpu family : 16
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model : 6
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model name : AMD Athlon(tm) II X2 270 Processor
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stepping : 3
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microcode : 0x10000c8
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cpu MHz : 800.000
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cache size : 1024 KB
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----
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