proc(7) - SerenityOS man pages

Name

proc - SerenityOS ProcFS

Description

The kernel can expose process related information in /proc. This functionality is used by various userland programs. Most of the output layout in the ProcFS nodes is JSON.

Global entries

all - this node exports a list of all processes that currently exist.
cmdline - this node exports the kernel boot commandline that was passed to from the bootloader.
cpuinfo - this node exports information on the CPU.
devices - this node exports information on all devices that might be represented by a device file.
df - this node exports information on mounted filesystems and basic statistics on them.
dmesg - this node exports information from the kernel log.
interrupts - this node exports information on all IRQ handlers and basic statistics on them.
kernel_base - this node reveals the loading address of the kernel.
keymap - this node exports information on current used keymap.
memstat - this node exports statistics on memory allocation in the kernel.
pci - this node exports information on all currently-discovered PCI devices in the system.

`net` directory

adapters - this node exports information on all currently-discovered network adapters.
arp - this node exports information on the kernel ARP table.
local - this node exports information on local (unix) sockets.
tcp - this node exports information on tcp sockets.
udp - this node exports information on udp sockets.

`sys` directory

This subdirectoy includes global settings of the kernel.

caps_lock_to_ctrl - this node controls remapping of of caps lock to the Ctrl key.
kmalloc_stacks - this node controls whether to send information about kmalloc to debug log.
ubsan_is_deadly - this node controls the deadliness of the kernel undefinied behavior sanitizer errors.

Per process entries

cwd - a symbolic link to current work directory of a process.
exe - a symbolic link to the executable binary of the process.
fds - this node exports information on all currently open file descriptors.
fd - this directory lists all currently open file descriptors.
perf_events - this node exports information being gathered during a profile on a process.
pledge - this node exports information on all the pledge requests and promises of a process.
stacks - this directory lists all stack traces of process threads.
unveil - this node exports information on all the unveil requests of a process.
vm - this node exports information on virtual memory mappings of a process.

Consistency and stability of data across multiple read operations

When opening a data node, the kernel generates the required data so it's prepared for read operation when requested to. However, in order to ensure that multiple reads will not create a corrupted data from that data node, a read operation alone will not inquire the kernel to refresh the data. To keep data output being refreshed, the userland has to re-open the data node with a new file descriptor, or to perform the lseek syscall on the open file descriptor to reset the the offset to 0.