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diff --git a/_ldd.xml b/_ldd.xml
index 3d7a928..fbc7570 100644
--- a/_ldd.xml
+++ b/_ldd.xml
@@ -56,7 +56,7 @@ write
close
-seek
+lseek
ioctl
@@ -75,14 +75,118 @@ once at a time.
int open (char * filename, int flags);
-flags may be O_RDONLY, O_WRONLY, O_RDWR and many others, some not
+flags may be O\_RDONLY, O\_WRONLY, O\_RDWR and many others, some not
important for devices.
Example:
-fd = open ("/dev/ttyS0", O_RDWR);
+fd = open ("/dev/ttyS0", O\_RDWR);
+
+
+
+
+close
+
+The close system call closes an open file.
+
+
+int close (int fd);
+
+
+Example:
+
+
+close (fd);
+
+
+
+
+read
+
+The read system call reads data from an open file into a buffer. For
+devices, it reads from the device.
+
+
+int read (int fd, char *buffer, int bsz);
+
+
+Read returns the number of bytes written into the buffer, which may be
+less than the number of bytes requested for any number of reasons.
+
+
+Example:
+
+
+c = read (fd, buffer, sizeof (buffer));
+
+
+
+
+write
+
+The write system call writes data to an open file from a buffer. For
+devices, it writes to the device.
+
+
+int write (int fd, char *buffer, int bsz);
+
+
+Write returns the number of bytes written to the file, which may be
+less than the number of bytes requested for any number of reasons.
+
+
+Example:
+
+
+c = write (fd, buffer, strlen (buffer));
+
+
+
+
+lseek
+
+The lseek system call changes the current position of the file, allowing
+to read or write in that position. Seeking on a device may have many
+different meanings.
+
+
+off\_t lseek (int fd, off\_t pos, int whence);
+
+
+The meaning of the position depends on the value of whence, which can be
+SEEK\_SET (the absolute position), SEEK\_CUR (relative to the current
+position), SEEK\_END (relative to the end of the file).
+
+
+Example:
+
+
+lseek (fd, 0, SEEK\_END);
+
+
+
+
+ioctl
+
+The ioctl system call is a catch-all operation. For those operations
+which doesn't fit in the read/write model, the ioctl allows the user to
+send a command with an optional argument to the device. This command may
+accept input or generate output.
+
+
+int ioctl (int fd, int request, char *arg);
+
+
+The last argument is optional and depends on the type of request. Every
+device or device class may have its different set of ioctl's.
+
+
+Example:
+
+
+struct ifreq req; ioctl (fd, SIOCGIFFLAGS, \&req);