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.
