vlimit(3C)                     DG/UX R4.11MU05                    vlimit(3C)


NAME
       vlimit - control maximum system resource consumption

SYNOPSIS
       #include <sys/vlimit.h>

       vlimit(resource, value)

DESCRIPTION
       Limits the consumption by the current process and each process it
       creates to not individually exceed value on the specified resource.
       If value is specified as -1, then the current limit is returned and
       the limit is unchanged.  The resources which are currently
       controllable are:

       LIM_NORAISE    A pseudo-limit; if set non-zero then the limits may
                      not be raised.  Only a user with appropriate privilege
                      (see NOTES, below) may remove the noraise restriction.

       LIM_CPU        Maximum number of cpu-seconds to be used by each
                      process

       LIM_FSIZE      Size of the largest single file that can be created

       LIM_DATA       Maximum growth beyond the end of program text of the
                      data+stack region via sbrk(2)

       LIM_STACK      Maximum size of the automatically-extended stack
                      region

       LIM_CORE       Size of the largest core dump that may be created.

       LIM_MAXRSS     Soft limit for the amount of physical memory (in
                      bytes) to be given to the program.  This information
                      is specified for the system's benefit; if memory is
                      tight, the system will prefer to take memory from
                      processes that are exceeding their declared
                      LIM_MAXRSS.

       Because specifications from this call are stored in the per-process
       information, this system call must be executed directly by the shell
       if it is to affect all future processes created by the shell; limit
       is thus a built-in command to csh(1).

       The system refuses to extend the data or stack space when the limits
       would be exceeded in the normal way; a break call fails if the data
       space limit is reached, or the process is killed when the stack limit
       is reached (since the stack cannot be extended, there is no way to
       send a signal).

       A file I/O operation that would violate file-size limits during
       creation will cause a signal SIGXFSZ to be generated. This signal
       normally terminates the process, but may be caught.  When the CPU
       time limit is exceeded, a signal SIGXCPU is sent to the offending
       process; to allow the process time to handle the signal, it adds five
       seconds to the CPU time limit.

SEE ALSO
       csh(1), appropriate_privilege(5),
       f4cap_defaults(5).

BUGS
       If LIM_NORAISE is set, then no grace should be given when the CPU
       time limit is exceeded.

       There should be limit and unlimit commands in sh(1) as well as in
       csh.

NOTES
       On a traditional DG/UX system, appropriate privilege is granted by
       having an effective UID of 0 (root).  See the
       appropriate_privilege(5) man page for more information.

       On a system with DG/UX information security, appropriate privilege is
       granted by having one or more specific capabilities enabled in the
       effective capability set of the user.  See cap_defaults(5) for the
       default capabilities for this command.



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