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In computing, redirection is a form of interprocess communication, and is a function common to most command-line interpreters, including the various Unix shells that can redirect standard streams to user-specified locations. The concept of redirection is quite old, dating back to the earliest operating systems (OS).
PowerShell is a task automation and configuration management program from Microsoft, consisting of a command-line shell and the associated scripting language.Initially a Windows component only, known as Windows PowerShell, it was made open-source and cross-platform on August 18, 2016, with the introduction of PowerShell Core. [9]
The directory stack underlies the functions of these two commands. It is an array of paths stored as an environment variable in the CLI, which can be viewed using the command dirs in Unix or Get-Location -stack in PowerShell. The current working directory is always at the top of the stack.
The parentheses in the C shell example are to avoid having the bit-shifting operators confused as I/O redirection operators. In either language, parentheses can always be used to explicitly specify the desired order of evaluation, even if only for clarity. Return values are limited to 8-bit.
In these systems the user might traverse through a series of sub-modes. For example, if the CLI had two modes called interface and system, the user might use the command interface to enter the interface mode. At this point, commands from the system mode may not be accessible until the user exits the interface mode and enters the system mode.
Example usage of tee: The output of ls -l is redirected to tee which copies them to the file file.txt and to the pager less. The name tee comes from this scheme - it looks like the capital letter T. The tee command is normally used to split the output of a program so that it can be both displayed and saved in a file. The command can be used to ...
A restricted mode is part of the POSIX specification for shells, and most of the Linux/Unix shells support such a mode where several of the built-in commands are disabled and only external commands from a certain directory can be invoked. [72] [73] PowerShell supports restricted modes through session configuration files or session ...
Most of the available string libraries [55] for C contain code which implements trimming, or functions that significantly ease an efficient implementation. The function has also often been called EatWhitespace in some non-standard C libraries. In C, programmers often combine a ltrim and rtrim to implement trim: