Influence
The C shell was extremely successful in introducing a large number of innovations including the history mechanism, aliases, tilde notation, interactive filename completion, an expression grammar built into the shell, and more, that have since been copied by other Unix shells. But in contrast to sh, which has spawned a large number of independently-developed clones, including ksh and bash, only two csh clones are known. (Since tcsh was based on the csh code originally written by Bill Joy, it is not considered a clone.)
In 1986, Allen Holub wrote On Command: Writing a Unix-Like Shell for MS-DOS, a book describing a program he had written called "SH" but which in fact copied the language design and features of csh, not sh. Companion diskettes containing full source for SH and for a basic set of Unix-like utilities (cat, cp, grep, etc.) were available for $25 and $30, respectively, from the publisher. The control structures, expression grammar, history mechanism and other features in Holub's SH were identical to those of the C shell.
In 1988, Hamilton Laboratories began shipping Hamilton C shell, written by Nicole Hamilton, for OS/2. It included both a csh clone and a set of Unix-like utilities. In 1992, Hamilton C shell was released for Windows NT. The Windows version continues to be actively supported but the OS/2 version was discontinued in 2003. An early quick reference described the intent as "full compliance with the entire C shell language (except job control)" but with improvements to the language design and adaptation to the differences between Unix and a PC. The most important improvement was a top-down parser that allowed control structures to be nested or piped, something the original C shell could not support, given its ad hoc parser. Hamilton also added new language features including built-in and user-defined procedures, block-structured local variables and floating point arithmetic. Adaptation to a PC included support for the filename and other conventions on a PC and the use of threads instead of forks (which were not available under either OS/2 or Windows) to achieve parallelism, e.g., in setting up a pipeline.
C shell has been, and continues to be, the dominant scripting language in much of the speech recognition research community, and is closely associated with the HTK speech tools.
Read more about this topic: C Shell
Famous quotes containing the word influence:
“The Family is the Country of the heart. There is an angel in the Family who, by the mysterious influence of grace, of sweetness, and of love, renders the fulfilment of duties less wearisome, sorrows less bitter. The only pure joys unmixed with sadness which it is given to man to taste upon earth are, thanks to this angel, the joys of the Family.”
—Giuseppe Mazzini (1805–1872)
“We could not well camp higher, for want of fuel; and the trees here seemed so evergreen and sappy, that we almost doubted if they would acknowledge the influence of fire; but fire prevailed at last, and blazed here, too, like a good citizen of the world.”
—Henry David Thoreau (1817–1862)
“Poets are the hierophants of an unapprehended inspiration; the mirrors of the gigantic shadows which futurity casts upon the present; the words which express what they understand not; the trumpets which sing to battle and feel not what they inspire; the influence which is moved not, but moves. Poets are the unacknowledged legislators of the world.”
—Percy Bysshe Shelley (1792–1822)