gabriel rosenkoetter on Thu, 5 Dec 2002 16:20:09 -0500


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Re: [PLUG] System Resource


On Thu, Dec 05, 2002 at 12:45:48PM -0500, Naresh wrote:
> Actually it was running an environment like MPI. I don't like ulimit(3)
> because I didn't find any good docs, examples more imporatant. Do you know
> of any good examples of ulimit(3)?

ulimit(3) is a library call (as dictated by its manual section,
see man(1)). All shells have a built-in ulimit function, so check
your local shell man pages. For zsh, there's this in zshbuiltins(1):

       ulimit [ -SHacdflmnpstv [ limit ] ... ]
              Set or display resource limits of the shell and the
              processes started by the shell.  The value of limit
              can be a number in the unit specified below or  the
              value  `unlimited'.   If  the  -H flag is given use
              hard limits instead of soft limits.  If the -S flag
              is  given  together  with the -H flag set both hard
              and soft limits.  If no options are used, the  file
              size  limit  (-f)  is assumed.  If limit is omitted
              the current value of the  specified  resources  are
              printed.   When  more  than one resource values are
              printed the limit name and unit is  printed  before
              each value.

              -a     Lists all of the current resource limits.
              -c     512-byte blocks on the size of core dumps.
              -d     K-bytes on the size of the data segment.
              -f     512-byte  blocks  on the size of files writ­
                     ten.
              -l     K-bytes on the size of locked-in memory.
              -m     K-bytes on the size of physical memory.
              -n     open file descriptors.
              -s     K-bytes on the size of the stack.
              -t     CPU seconds to be used.
              -u     processes available to the user.
              -v     K-bytes on the size of virtual memory.

bash(1) says:

       ulimit [-SHacdflmnpstuv [limit]]
              Provides control over the  resources  available  to
              the  shell  and to processes started by it, on sys­
              tems that  allow  such  control.   The  -H  and  -S
              options  specify that the hard or soft limit is set
              for the given resource.  A  hard  limit  cannot  be
              increased  once  it  is  set;  a  soft limit may be
              increased up to the value of the  hard  limit.   If
              neither  -H  nor -S is specified, both the soft and
              hard limits are set.  The value of limit can  be  a
              number  in  the  unit specified for the resource or
              one of the special values hard, soft, or unlimited,
              which stand for the current hard limit, the current
              soft limit, and no limit, respectively.   If  limit
              is  omitted, the current value of the soft limit of
              the resource is printed, unless the  -H  option  is
              given.   When  more than one resource is specified,
              the limit name and  unit  are  printed  before  the
              value.  Other options are interpreted as follows:
              -a     All current limits are reported
              -c     The maximum size of core files created
              -d     The maximum size of a process's data segment
              -f     The maximum size of  files  created  by  the
                     shell
              -l     The  maximum  size  that  may be locked into
                     memory
              -m     The maximum resident set size
              -n     The maximum number of open file  descriptors
                     (most  systems do not allow this value to be
                     set)
              -p     The pipe size in 512-byte blocks  (this  may
                     not be set)
              -s     The maximum stack size
              -t     The maximum amount of cpu time in seconds
              -u     The maximum number of processes available to
                     a single user
              -v     The maximum amount of virtual memory  avail­
                     able to the shell

              If limit is given, it is the new value of the spec­
              ified resource (the -a option is display only).  If
              no option is given, then -f is assumed.  Values are
              in 1024-byte increments, except for -t, which is in
              seconds,  -p, which is in units of 512-byte blocks,
              and -n and -u,  which  are  unscaled  values.   The
              return  status  is  0  unless  an invalid option or
              argument is supplied, or an error occurs while set­
              ting a new limit.

Good enough for ya?

-- 
gabriel rosenkoetter
gr@eclipsed.net

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