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Test Your Knowledge in Computers #713
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The shared bus between the program memory and data memory leads to the von Neumann bottleneck, the limited throughput (data transfer rate) between the CPU and memory compared to the amount of memory.
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setxattr(2) [bsd man page]

SETXATTR(2)						     Linux Programmer's Manual						       SETXATTR(2)

NAME
setxattr, lsetxattr, fsetxattr - set an extended attribute value SYNOPSIS
#include <sys/types.h> #include <attr/xattr.h> int setxattr(const char *path, const char *name, const void *value, size_t size, int flags); int lsetxattr(const char *path, const char *name, const void *value, size_t size, int flags); int fsetxattr(int fd, const char *name, const void *value, size_t size, int flags); DESCRIPTION
Extended attributes are name:value pairs associated with inodes (files, directories, symbolic links, etc.). They are extensions to the normal attributes which are associated with all inodes in the system (i.e., the stat(2) data). A complete overview of extended attributes concepts can be found in attr(5). setxattr() sets the value of the extended attribute identified by name and associated with the given path in the file system. The size of the value must be specified. lsetxattr() is identical to setxattr(), except in the case of a symbolic link, where the extended attribute is set on the link itself, not the file that it refers to. fsetxattr() is identical to setxattr(), only the extended attribute is set on the open file referred to by fd (as returned by open(2)) in place of path. An extended attribute name is a simple null-terminated string. The name includes a namespace prefix; there may be several, disjoint names- paces associated with an individual inode. The value of an extended attribute is a chunk of arbitrary textual or binary data of specified length. The flags argument can be used to refine the semantics of the operation. XATTR_CREATE specifies a pure create, which fails if the named attribute exists already. XATTR_REPLACE specifies a pure replace operation, which fails if the named attribute does not already exist. By default (no flags), the extended attribute will be created if need be, or will simply replace the value if the attribute exists. RETURN VALUE
On success, zero is returned. On failure, -1 is returned and errno is set appropriately. If XATTR_CREATE is specified, and the attribute exists already, errno is set to EEXIST. If XATTR_REPLACE is specified, and the attribute does not exist, errno is set to ENOATTR. If there is insufficient space remaining to store the extended attribute, errno is set to either ENOSPC, or EDQUOT if quota enforcement was the cause. If extended attributes are not supported by the file system, or are disabled, errno is set to ENOTSUP. The errors documented for the stat(2) system call are also applicable here. VERSIONS
These system calls have been available on Linux since kernel 2.4; glibc support is provided since version 2.3. CONFORMING TO
These system calls are Linux-specific. SEE ALSO
getfattr(1), setfattr(1), getxattr(2), listxattr(2), open(2), removexattr(2), stat(2), attr(5), symlink(7) COLOPHON
This page is part of release 3.25 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/. Linux 2001-12-31 SETXATTR(2)

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SETXATTR(2)						     Linux Programmer's Manual						       SETXATTR(2)

NAME
setxattr, lsetxattr, fsetxattr - set an extended attribute value SYNOPSIS
#include <sys/types.h> #include <attr/xattr.h> int setxattr(const char *path, const char *name, const void *value, size_t size, int flags); int lsetxattr(const char *path, const char *name, const void *value, size_t size, int flags); int fsetxattr(int fd, const char *name, const void *value, size_t size, int flags); DESCRIPTION
Extended attributes are name:value pairs associated with inodes (files, directories, symbolic links, etc.). They are extensions to the normal attributes which are associated with all inodes in the system (i.e., the stat(2) data). A complete overview of extended attributes concepts can be found in attr(5). setxattr() sets the value of the extended attribute identified by name and associated with the given path in the file system. The size of the value must be specified. lsetxattr() is identical to setxattr(), except in the case of a symbolic link, where the extended attribute is set on the link itself, not the file that it refers to. fsetxattr() is identical to setxattr(), only the extended attribute is set on the open file referred to by fd (as returned by open(2)) in place of path. An extended attribute name is a simple null-terminated string. The name includes a namespace prefix; there may be several, disjoint names- paces associated with an individual inode. The value of an extended attribute is a chunk of arbitrary textual or binary data of specified length. The flags argument can be used to refine the semantics of the operation. XATTR_CREATE specifies a pure create, which fails if the named attribute exists already. XATTR_REPLACE specifies a pure replace operation, which fails if the named attribute does not already exist. By default (no flags), the extended attribute will be created if need be, or will simply replace the value if the attribute exists. RETURN VALUE
On success, zero is returned. On failure, -1 is returned and errno is set appropriately. If XATTR_CREATE is specified, and the attribute exists already, errno is set to EEXIST. If XATTR_REPLACE is specified, and the attribute does not exist, errno is set to ENOATTR. If there is insufficient space remaining to store the extended attribute, errno is set to either ENOSPC, or EDQUOT if quota enforcement was the cause. If extended attributes are not supported by the file system, or are disabled, errno is set to ENOTSUP. The errors documented for the stat(2) system call are also applicable here. VERSIONS
These system calls have been available on Linux since kernel 2.4; glibc support is provided since version 2.3. CONFORMING TO
These system calls are Linux-specific. SEE ALSO
getfattr(1), setfattr(1), getxattr(2), listxattr(2), open(2), removexattr(2), stat(2), attr(5), symlink(7) COLOPHON
This page is part of release 3.25 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/. Linux 2001-12-31 SETXATTR(2)

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