32 bit Architecture and the hugemem Kernel
In Red Hat Enterprise Linux 3, 4 or 5 the smp kernel can be used on systems with up to 16 GB of RAM. The hugemem kernel is required in order to use all the memory on systems that have more than 16GB of RAM up to 64GB. However, it is recommend to use the hugemem kernel even on systems that have 8GB of RAM or more due to the potential issue of “low memory” starvation (see next section) that can happen on database systems with 8 GB of RAM. The stability you get with the hugemem kernel on larger systems outperforms the performance overhead of address space switching.
restricted deletion flag or sticky bit is a single bit
The restricted deletion flag or sticky bit is a single bit, whose interpretation depends on the file type. For directories, it prevents unprivileged users from removing or renaming a file in the directory unless they own the file or the directory; this is called the restricted deletion flag for the directory, and is commonly found on world-writable directories like /tmp.
For regular files on some older systems, the bit saves the program’s text image on the swap device so it will load more quickly when run; this is called the sticky bit.
The letters rwxXst select file mode bits for the affected users: read (r), write (w), execute (or search for directories) (x), execute/search only if the file is a directory or already has execute permission for some user (X), set user or group ID on execution (s), restricted deletion flag or sticky bit (t). Instead of one or more of these let-ters, you can specify exactly one of the letters ugo: the permissions granted to the user who owns the file (u), the permissions granted to other users who are members of the file’s group (g), and the permissions granted to users that are in neither of the two preceding categories (o).
A numeric mode is from one to four octal digits (0-7), derived by adding up the bits with values 4, 2, and 1. Omitted digits are assumed to be leading zeros. The first digit selects the set user ID (4) and set group ID (2) and restricted deletion or sticky (1) attributes. The second digit selects permissions for the user who owns the file: read (4), write (2), and execute (1); the third selects permissions for other users in the file’s group, with the same values; and the fourth for other users not in the file’s group, with the same values.
Only the person who created the file within a directory may delete it, even if other people have write permission. You can turn it on by typing:
chmod 1700 somedirectory (where 1 = sticky bit)
Find If Processor CPU is 64 bit or 32 bit
Try this to find out if your CPU/Processor is 32 bit or 64 bit
NAME
getconf - Query system configuration variables
SYNOPSIS
getconf [-v specification] system_var
getconf [-v specification] path_var pathname
DESCRIPTION
-v
Indicate the specification and version for which to obtain
configuration variables.
system_var
A system configuration variable, as defined by sysconf(3) or
confstr(3).
path_var
A system configuration variable as defined by pathconf(3). This
must be used with a pathname.
