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Full Discussion: File Descriptors
Top Forums UNIX for Advanced & Expert Users File Descriptors Post 33116 by Perderabo on Tuesday 17th of December 2002 11:31:09 AM
Old 12-17-2002
You're worried about file descriptors?

File descriptors use a trivial amount of memory and I don't understand what it is that you're worried about. Each time you remove a file descriptor from your system you get back the space required to store two shorts and one pointer. Are you really that tight on swap space?

Your average fd will also require a file table entry, but even that isn't a real big deal. If I open() a file, and then dup()it 100 times, I will have 101 fd's all pointing at the same file table entry. That would be a little crazy, but lots of processes have stdout and stderr pointing to the same file table entry, so assuming a correspondence between fd's and open files is wrong.

Any process can change its soft limit to any value that does not exceed its hard limit. Any process may lower its hard limit. A root process can raise its hard limit.

We have some 5.5.1 systems and we use lsof on them all the time. But pfiles in included with 5.5.1 and might be a better choice for you anyway.
 

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plimit(1)							   User Commands							 plimit(1)

NAME
plimit - get or set the resource limits of running processes SYNOPSIS
plimit [-km] pid... plimit {-cdfnstv} soft,hard... pid... DESCRIPTION
If one or more of the cdfnstv options is specified, plimit sets the soft (current) limit and/or the hard (maximum) limit of the indicated resource(s) in the processes identified by the process-ID list, pid. Otherwise plimit reports the resource limits of the processes identi- fied by the process-ID list, pid. Only the owner of a process or the super-user is permitted either to get or to set the resource limits of a process. Only the super-user can increase the hard limit. OPTIONS
The following options are supported: -k On output, show file sizes in kilobytes (1024 bytes) rather than in 512-byte blocks. -m On output, show file and memory sizes in megabytes (1024*1024 bytes). The remainder of the options are used to change specified resource limits. They each accept an argument of the form: soft,hard where soft specifies the soft (current) limit and hard specifies the hard (maximum) limit. If the hard limit is not specified, the comma may be omitted. If the soft limit is an empty string, only the hard limit is set. Each limit is either the literal string unlimited, or a number, with an optional scaling factor, as follows: nk n kilobytes nm n megabytes (minutes for CPU time) nh n hours (for CPU time only) mm:ss minutes and seconds (for CPU time only) The soft limit cannot exceed the hard limit. -c soft,hard Set core file size limits (default unit is 512-byte blocks). -d soft,hard Set data segment (heap) size limits (default unit is kilobytes). -f soft,hard Set file size limits (default unit is 512-byte blocks). -n soft,hard Set file descriptor limits (no default unit). -s soft,hard Set stack segment size limits (default unit is kilobytes). -t soft,hard Set CPU time limits (default unit is seconds). -v soft,hard Set virtual memory size limits (default unit is kilobytes). OPERANDS
The following operands are supported. pid Process ID list. EXIT STATUS
plimit returns the exit value zero on success, non-zero on failure (such as no such process, permission denied, or invalid option). FILES
/proc/pid/* process information and control files ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWesu | +-----------------------------+-----------------------------+ SEE ALSO
ulimit(1), proc(1), getrlimit(2), setrlimit(2), proc(4), attributes(5), SunOS 5.11 8 Jun 1998 plimit(1)
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