Role of shell
Main access to the UNIX operating system and as such any improvement to it can result in considerably more effective use of the system, increased speed, efficiency and file properties.
This shell is good for interactive work and also added some features from other Operating shells. The Korn shell became part of System V but had one major problem; unlike the rest of the UNIX shells it wasn't free, you had to pay AT&T for it.
It has a very strong powerful
syntactical language built into it, with all the features that are commonly considered to produce structured programs; it has particularly strong provisions for controlling input and output and in its expression matching facilities. But no matter how strong its input language is, it had one major drawback; it made nearly no concessions to the interactive user and so there was a gap for something better.
A free shell, also it was decided that they wanted to
make this new shell POSIX compatible, thus bash (the Bourne again shell) was born. Like the Korn shell bash was based upon the Bourne shell’s language and like the Korn shell, it also pinched features from the C shell and other operating systems, but unlike the Korn shell it is free. Bash was quickly adopted for LINUX, and is the most popular of the free new generation shells.
Three features and roles of each feature
FreeBSD 7.0, released February 2008, brings many new features and performance enhancements. With a special focus on storage and multiprocessing performance, FreeBSD 7.0 shipped with support for Sun's ZFS file system and highly scalable multiprocessing performance. Benchmarks have shown that FreeBSD provides twice the MySQL and PostgreSQL performance as current Linux systems on 8-core servers.
From BSD: TCP/IP support, sockets, ufs, support for multiple groups, csh From SunOS: the virtual file system interface (replacing the one in System V release 3,...
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