The /proc directory on GNU/Linux systems provides a file-system like interface to the kernel. This allows applications and users to fetch information from and set values in the kernel using normal file-system I/O operation.
The proc file system is sometimes referred to as a process
information pseudo-file system. It does not contain ``real'' files
but rather runtime system information
(e.g. system memory, devices mounted, hardware configuration,
etc). For this reason it can be regarded as a control and information
center for the kernel. In fact, quite a lot of system utilities are
simply calls to files in this directory. For example, the command
lsmod, which lists the modules loaded by the kernel, is basically the
same as '
cat /proc/modules' while
lspci, which lists
devices connected to the PCI bus of the system, is the same
cat /proc/pci'. By altering files located in this directory you can
change kernel parameters while the system is running.
The proc(5) manual page describes most entries in detail.