lseek(2)
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lseek System Call
Change object pointer's current position.
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SYNTAX
#define SEEK_SET
#define SEEK_CUR
#define SEEK_END
#include <sys/file.h>
#include <sys/types.h>
off_t lseek (fildes, offset, whence)
int fildes;
off_t offset;
int whence;
PARAMETERS
fildes A valid, active file descriptor.
offset The new position of the file pointer.
whence Changes the interpretation of <offset>.
DESCRIPTION
If <fildes> is a valid, active descriptor that refers to an
object pointer having a current position attribute, the object
pointer's current position is modified according to the <offset>
and <whence> parameters as follows:
If <whence> is SEEK_SET, the current position is set to <offset>
bytes.
If <whence> is SEEK_CUR, the current position is set to its
current location plus <offset>.
If <whence> is SEEK_END, the current position is set to the size
of the object plus <offset>. The size of character special files
and block special files is always zero. Hence, this option is
equivalent to <whence> being SEEK_SET for these files.
If <whence> is equal to any other value, the user is sent the
signal SIGSYS and errno returns EINVAL.
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lseek(2)
It is an error for the new current position attribute to be
negative.
If lseek fails, the object pointer is not changed.
ACCESS CONTROL
None.
RETURN VALUE
<position> Completed successfully. The object pointer's new
position is returned.
-1 An error occurred. Errno is set to indicate the
error.
EXCEPTIONS
Errno may be set to one of the following error codes:
EBADF <Fildes> is not a valid, active descriptor.
ESPIPE <Fildes> is associated with a pipe or a socket.
EINVAL and SIGSYS signal
<Whence> is not SEEK_SET, SEEK_CUR, or SEEK_END.
EINVAL The resulting file pointer would be negative.
SEE ALSO
The related manual sections: creat(2), dup(2), dup2(2),
fcntl(2), open(2).
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