Visit Our UNIX and Linux User Community

Linux and UNIX Man Pages

Test Your Knowledge in Computers #563
Difficulty: Medium
The comparison operators are only used for comparing numerical data types.
True or False?
Linux & Unix Commands - Search Man Pages

cgread(3) [freebsd man page]

CGREAD(3)						   BSD Library Functions Manual 						 CGREAD(3)

NAME
cgread, cgread1, cgwrite1 -- read/write cylinder groups of UFS disks LIBRARY
UFS File System Access Library (libufs, -lufs) SYNOPSIS
#include <sys/param.h> #include <sys/mount.h> #include <ufs/ufs/ufsmount.h> #include <ufs/ufs/dinode.h> #include <ufs/ffs/fs.h> #include <libufs.h> int cgread(struct uufsd *disk); int cgread1(struct uufsd *disk, int c); int cgwrite1(struct uufsd *disk, int c); DESCRIPTION
The cgread() and cgread1() functions provide cylinder group reads for libufs(3) consumers. The cgread1() function reads from one cylinder group, specified by c into the d_cg field of a userland UFS disk structure. It sets the d_lcg field to the cylinder group number c. The cgread() function operates on sequential cylinder groups. Calling the cgread() function is equivalent to calling cgread1() with a cylin- der group specifier equivalent to the value of the current d_ccg field, and then incrementing the d_ccg field. The cgwrite1() function stores cylinder group specified by c from d_cg field of a userland UFS disk structure on disk. RETURN VALUES
Both functions return 0 if there are no more cylinder groups to read, 1 if there are more cylinder groups, and -1 on error. ERRORS
The function cgread() may fail and set errno for any of the errors specified for the library function bread(3). The function cgread1() has semantically identical failure conditions to those of cgread(). The function cgwrite1() may fail and set errno for any of the errors specified for the library function bwrite(3). SEE ALSO
bread(3), bwrite(3), libufs(3) HISTORY
These functions first appeared as part of libufs(3) in FreeBSD 5.1. AUTHORS
Juli Mallett <jmallett@FreeBSD.org> BSD
June 4, 2003 BSD

Check Out this Related Man Page

BREAD(3)						   BSD Library Functions Manual 						  BREAD(3)

NAME
bread, bwrite -- read and write blocks of a UFS file system LIBRARY
UFS File System Access Library (libufs, -lufs) SYNOPSIS
#include <sys/param.h> #include <sys/mount.h> #include <ufs/ufs/ufsmount.h> #include <ufs/ufs/dinode.h> #include <ufs/ffs/fs.h> #include <libufs.h> ssize_t bread(struct uufsd *disk, ufs2_daddr_t blockno, void *data, size_t size); ssize_t bwrite(struct uufsd *disk, ufs2_daddr_t blockno, const void *data, size_t size); int berase(struct uufsd *disk, ufs2_daddr_t blockno, ufs2_daddr_t size); DESCRIPTION
The bread(), bwrite() and berase() functions provide a block read, write and erase API for libufs(3) consumers. They operate on a userland UFS disk structure, and perform the read and write at a given block address, which uses the current d_bsize value of the structure. RETURN VALUES
The bread() and bwrite() functions return the amount read or written, or -1 in case of any error, including short read. The berase() function returns non-zero on error. ERRORS
The function bread() may fail and set errno for any of the errors specified for the library functions ufs_disk_write(3) or pread(2). The function bwrite() may fail and set errno for any of the errors specified for the library function pwrite(2). The function berase() may fail and set errno for any of the errors specified for the library function ioctl(2). Additionally all three functions may follow the libufs(3) error methodologies in situations where the amount of data written is not equal to the amount requested, or in case of a device error. SEE ALSO
libufs(3), ufs_disk_write(3) HISTORY
These functions first appeared as part of libufs(3) in FreeBSD 5.0. AUTHORS
Juli Mallett <jmallett@FreeBSD.org> BSD
June 4, 2003 BSD

Featured Tech Videos