segunda-feira, agosto 30, 2004
LX PS all
ps -aux |sort
LX LS all
LX Monitor do sistema GNOME
LX Biblicoteca C do Linux
LX Cor do terminal
LX Red Hat Tutorial
LX DTE cables for a 25-pin connector
Terminal Computer Meaning
Pin Pin
1 1 Ground
2 3 Transmit data / receive data
3 2 Receive data / transmit data
4 4 Ready to send
5 5 Clear to send
6 20 Data set ready / data terminal ready
7 7 Ground
8 20 Carrier detect / data terminal ready
20 6, 8 Data terminal ready / data set ready, carrier detect
LX Major and Minor Device Numbers
There might be more than one device of the same type on a system. For example, your Linux system might have a multiport card (multiple serial ports) with 10 Wyse 60 terminals hanging off it. Linux can use the same device driver for each of the terminals because they are all the same type of device.
However, there must be a method for the operating system to differentiate which one of the 10 terminals you want to address. That's where device numbers are used. Each device is identified by two device numbers: The major number identifies the device driver to be used, and the minor number identifies the device number. For example, the 10 Wyse 60 terminals on the multiport card can all use a device file with the same major number, but each will have a different minor number, thereby uniquely identifying it to the operating system.
Every device on the system has both major and minor device numbers assigned in such a way as to ensure that they are unique. If two devices are assigned the same number, Linux can't properly communicate with them.
Some devices use the major and minor device numbers in a strange way. Some tape drives, for example, use the minor number to identify the density of the tape and adjust its output in that manner.
Device files are created with the command mknod (make node) and removed with the standard rm command.
However, there must be a method for the operating system to differentiate which one of the 10 terminals you want to address. That's where device numbers are used. Each device is identified by two device numbers: The major number identifies the device driver to be used, and the minor number identifies the device number. For example, the 10 Wyse 60 terminals on the multiport card can all use a device file with the same major number, but each will have a different minor number, thereby uniquely identifying it to the operating system.
Every device on the system has both major and minor device numbers assigned in such a way as to ensure that they are unique. If two devices are assigned the same number, Linux can't properly communicate with them.
Some devices use the major and minor device numbers in a strange way. Some tape drives, for example, use the minor number to identify the density of the tape and adjust its output in that manner.
Device files are created with the command mknod (make node) and removed with the standard rm command.
