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While the command is executing, the shell waits for the process to finish.
Wiki User
∙ 12y ago
Wiki User
∙ 12y agoNormally it just returns to the prompt.
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Are commands other than shell built-in executed in kernel?
No. All commands are executed in userspace. If the command is not built-in to the shell, it will look in a binary directory (/sbin, /bin, /usr/bin, or /usr/local/bin) for a program matching that name.
What environment variable contains a list of directories on the Linux system that the shell searches each time a command is executed?
The PATH variable.
What happens if the argument to exec is not executable?
If command is not specified, a non-interactive shell exits, unless the shell option exefail is enabled, in which case if returns failure. Returns if file cannot be executed.
What is the Purpose of exit command in Shell of Unix?
The 'exit' command allows you to stop a running shell script at any point and to return a "status" value back to whomever called the shell script. This is a very common practice with shell scripts; sometimes you want to stop the script before it gets to the end of the shell script (for various logic reasons). The 'exit' command also allows you to give a status that any other calling process can use to determine if the shell script ended successfully or not.
When the shell finds met a character in the command line what does it do?
The shell interpreter must substitute or convert all metacharacters in the command line before the command parameters are given to a program. Once all metacharacters have been removed and replaced by their equivalents the program is then executed.
What shell was developed as the first UNIX command processor?
The first command shell was 'sh', the Bourne shell (Steven Bourne).
What is the difference between interactive use of shell command and running a shell?
In an interactive shell session the shell program waits for the user to type in a command. When receiving a command the shell program will then attempt to locate it and process (execute) the command. You are interacting with the shell. Running a shell file requires a pre-stored series of commands stored in a file. Unless the shell program you are running is interactive then the shell executes each command in sequence, without involving the user at all.
What does the shell ordinary do while a command is executing?
While the command is executing, the shell waits for the process to finish.
What system calls have to executed by a command interpreter or shell in order to start a new process?
The fork system call is used to create new child process which followed his parent process
Distinguish between internal and extarnal commands with examples for unix?
Internal commands are executed by the shell and do not exist as a separate binary program. You can find out which of these there are by looking at the 'man' entry for the shell you are using. External commands can be found in various directories, such as /bin, /usr/bin, etc.
What is the difference between Kernel and Shell?
Your interface to the operating system is called a shell.The shell is the outermost layer of the operating system. Shells incorporate a programming language to control processes and files, as well as to start and control other programs. The shell manages the interaction between you and the operating system by prompting you for input, interpreting that input for the operating system, and then handling any resulting output from the operating system.Shells provide a way for you to communicate with the operating system. This communication is carried out either interactively (input from the keyboard is acted upon immediately) or as a shell script. A shell script is a sequence of shell and operating system commands that is stored in a file.When you log in to the system, the system locates the name of a shell program to execute. After it is executed, the shell displays a command prompt. This prompt is usually a $ (dollar sign). When you type a command at the prompt and press the Enter key, the shell evaluates the command and attempts to carry it out. Depending on your command instructions, the shell writes the command output to the screen or redirects the output. It then returns the command prompt and waits for you to type another command.
What is the output of the command 'echo shell shell'?
The output would be 'shell shell' (without the quotes, of course)
