73 lines
3.4 KiB
Markdown
73 lines
3.4 KiB
Markdown
## Name
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proc - SerenityOS ProcFS
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## Description
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The kernel can expose process related information in /proc.
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This functionality is used by various userland programs.
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Most of the output layout in the ProcFS nodes is JSON.
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### Global entries
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* **`all`** - this node exports a list of all processes that currently exist.
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* **`cmdline`** - this node exports the kernel boot commandline that was passed to
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from the bootloader.
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* **`cpuinfo`** - this node exports information on the CPU.
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* **`devices`** - this node exports information on all devices that might be represented
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by a device file.
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* **`df`** - this node exports information on mounted filesystems and basic statistics on
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them.
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* **`dmesg`** - this node exports information from the kernel log.
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* **`interrupts`** - this node exports information on all IRQ handlers and basic statistics on
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them.
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* **`kernel_base`** - this node reveals the loading address of the kernel.
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* **`keymap`** - this node exports information on current used keymap.
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* **`memstat`** - this node exports statistics on memory allocation in the kernel.
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* **`pci`** - this node exports information on all currently-discovered PCI devices in the system.
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### `net` directory
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* **`adapters`** - this node exports information on all currently-discovered network adapters.
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* **`arp`** - this node exports information on the kernel ARP table.
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* **`local`** - this node exports information on local (unix) sockets.
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* **`tcp`** - this node exports information on tcp sockets.
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* **`udp`** - this node exports information on udp sockets.
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### `sys` directory
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This subdirectoy includes global settings of the kernel.
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* **`caps_lock_to_ctrl`** - this node controls remapping of of caps lock to the Ctrl key.
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* **`kmalloc_stacks`** - this node controls whether to send information about kmalloc to debug log.
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* **`ubsan_is_deadly`** - this node controls the deadliness of the kernel undefinied behavior
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sanitizer errors.
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### Per process entries
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* **`cwd`** - a symbolic link to current work directory of a process.
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* **`exe`** - a symbolic link to the executable binary of the process.
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* **`fds`** - this node exports information on all currently open file descriptors.
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* **`fd`** - this directory lists all currently open file descriptors.
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* **`perf_events`** - this node exports information being gathered during a profile on a process.
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* **`pledge`** - this node exports information on all the pledge requests and promises of a process.
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* **`stacks`** - this directory lists all stack traces of process threads.
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* **`unveil`** - this node exports information on all the unveil requests of a process.
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* **`vm`** - this node exports information on virtual memory mappings of a process.
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### Consistency and stability of data across multiple read operations
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When opening a data node, the kernel generates the required data so it's prepared
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for read operation when requested to. However, in order to ensure that multiple reads
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will not create a corrupted data from that data node, a read operation alone will
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not inquire the kernel to refresh the data.
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To keep data output being refreshed, the userland has to re-open the data node with a
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new file descriptor, or to perform the `lseek` syscall on the open file descriptor to
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reset the the offset to 0.
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## See also
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* [`mount`(2))](../man2/mount.md).
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* [`boot_parameters`(7))](boot_parameters.md).
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* [`pledge`(2))](../man2/pledge.md).
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* [`unveil`(2))](../man2/unveil.md).
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