OS-Terminals in Unix

Terminals

The user terminal is an important feature of I/O in unix system. Each terminal types corresponds to different specifications and capabilities in terms of screen resolution, control code and color etc. terminals are identified by tly

(ie.,tly 01, tly 02) entries in the /dev directory. The term cap file is used by programs which utilize the more advanced features of user terminals.

File systems & allocation methods space allocation

The Unix directory system differs from other file system. Directory itself a set of structures called inodes, one of which is associated with each file.A directory entry simply holds the filename and a refrence to the appropriate inode for the file. Other file information like filesize, data of last access etc ate held in the inode. The inode performs the important task of recording which disk blocks are allocated to the file. Space for inodes are drawn from the pool of total disk space on the disk volume. The pool of inodes is sometimes viewed as a centralized directory.

The number of links field specifies the number of separate directory entries physical file can be knowh and referenced by several aliases.
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