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>> file means stdout will be appended at the end of file. >>& file means both stdout and stderr will be appended at the end of file. < file means stdin will be read from file. << string is a here document. Stdin will read the following lines up to the one that matches string. Redirecting stderr alone isn't possible without the aid of a sub-shell.
The source code comes with a 'complete.tcsh' file containing many examples of its completion syntax. Windows PowerShell , the extensible command shell from Microsoft, which is based on object-oriented programming and the Microsoft .NET framework, provides powerful and customizable completion capabilities similar to those of traditional Unix shells.
For example, the file rename command (variously called mv, move, or ren) is silent on success. Unless redirected , standard output is inherited from the parent process. In the case of an interactive shell, that is usually the text terminal which initiated the program.
This provides the interfaces of piping, filters and redirection. Under Unix, devices are files too, so the normal type of file for the shell used for stdin, stdout and stderr is a tty device file. Another command-line interface allows a shell program to launch helper programs, either to launch documents or start a program.
The “t” in tcsh comes from the “T” in TENEX, an operating system which inspired Ken Greer at Carnegie Mellon University, the author of tcsh, with its command-completion feature. [14] Greer began working on his code to implement Tenex-style file name completion in September 1975, finally merging it into the C shell in December 1981. [ 7 ]
Support for command history means that a user can recall a previous command into the command-line editor and edit it before issuing the potentially modified command. Shells that support completion may also be able to directly complete the command from the command history given a partial/initial part of the previous command.
In computing, a here document (here-document, here-text, heredoc, hereis, here-string or here-script) is a file literal or input stream literal: it is a section of a source code file that is treated as if it were a separate file.
In computing, process substitution is a form of inter-process communication that allows the input or output of a command to appear as a file. The command is substituted in-line, where a file name would normally occur, by the command shell. This allows programs that normally only accept files to directly read from or write to another program.