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Full Discussion: file descriptors
Top Forums UNIX for Dummies Questions & Answers file descriptors Post 46836 by fpmurphy on Tuesday 27th of January 2004 06:46:14 PM
Old 01-27-2004
Note that processes do not have a limit of 20 file descriptors
as suggested in your mail - rather the limit is OPEN_MAX.

Here is the formal POSIX definition of a file descriptor:

A per-process unique, non-negative integer used to identify an open file for the purpose of file access. The value of a file descriptor is from zero to OPEN_MAX. A process can have no more than OPEN_MAX file descriptors open simultaneously.

Note also the difference between file DESCRIPTOR and file DESCRIPTION. From SUSv3 ....

(Open) File Description

A record of how a process or group of processes is accessing a file. Each file descriptor refers to exactly one open file description, but an open file description can be referred to by more than one file descriptor. The file offset, file status, and file access modes are attributes of an open file description.

- Finnbarr
 

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HWLOC-PS(1)							       hwloc							       HWLOC-PS(1)

NAME
hwloc-ps - List currently-running processes that are bound. SYNOPSIS
hwloc-ps [options] OPTIONS
-a list all processes, even those that are not bound to any specific part of the machine. -p --physical report OS/physical indexes instead of logical indexes -l --logical report logical indexes instead of physical/OS indexes (default) -c --cpuset show process bindings as cpusets instead of objects. --whole-system Do not consider administration limitations. DESCRIPTION
By default, hwloc-ps lists only those currently-running processes that are bound; it displays their their identifier, command-line and binding. The binding may be reported as objects or cpusets. By default, process bindings are restricted to the currently available topol- ogy. If some processes are bound to processors that are not available to the current process, they are ignored unless --whole-system is given. The output is a plain list. If you wish to annotate the hierarchical topology with processes so as to see how they are actual dis- tributed on the machine, you might want to use lstopo --ps instead (which also only shows processes that are bound). The -a switch can be used to show all processes, if desired. SEE ALSO
hwloc(7), lstopo(1), hwloc-calc(1), hwloc-distrib(1) 1.4.1 Feb 27, 2012 HWLOC-PS(1)
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