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The test command in Unix evaluates the expression parameter. In most recent shell implementations, it is a shell builtin, even though the external version still exists.In the second form of the command, the [ ] (brackets) must be surrounded by blank spaces (this is because [is a program and POSIX compatible shells require a space between the program name and its arguments).
In computing, which is a command for various operating systems used to identify the location of executables. The command is available in Unix and Unix-like systems, the AROS shell, [4] for FreeDOS [5] and for Microsoft Windows. [2] The functionality of the which command is similar to some implementations of the type command.
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 capture intermediate output before the data is altered by another command or program. The tee command reads standard input, then writes its content to standard output. It simultaneously copies the ...
Some commands, such as echo, false, kill, printf, test or true, depending on your system and on your locally installed version of bash, can refer to either a shell built-in or a system binary executable file. When one of these command name collisions occurs, bash will by default execute a given command line using the shell built-in. Specifying ...
A Unix shell is a command-line interpreter or shell that provides a command line user interface for Unix-like operating systems. The shell is both an interactive command language and a scripting language , and is used by the operating system to control the execution of the system using shell scripts .
The program becomes modal, switching between interpreting commands from the keyboard or passing keystrokes on as data to be processed. A feature of many command-line shells is the ability to save sequences of commands for re-use. A data file can contain sequences of commands which the CLI can be made to follow as if typed in by a user.
A shell script is a computer program designed to be run by a Unix shell, a command-line interpreter. [1] The various dialects of shell scripts are considered to be command languages. Typical operations performed by shell scripts include file manipulation, program execution, and printing text.
The most notable example is the cd command, which changes the working directory of the shell. Since each executable program runs in a separate process , and working directories are specific to each process, loading cd as an external program would not affect the working directory of the shell that loaded it.