Environment Variables
Essay Preview: Environment Variables
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The environment is the most important concept of UNIX, which express by environment variables. The system is set by the users or system, yet some are set by the shell that loads to another program. The assign value is a variable, which is a character string. The value could be a text, number, filename, device, or any other type of data-files. The shell has important process to follow to execute the program. The shell will makes sure to check if the file /ect/profile exists. If the file exists, the shell reads it. If not, the file is skipped. No error message is displayed. The shell also checks if the .profile exists in the home directory. The home directory is the directory that user starts out in after user log in. The element of the UNIX variables are case-sensitive, other convention variables dictates that environment variables are typed in all upper case letters. If a user type the variable “SHELL” as “shell” it will not affect the environment SHELL variables. The function of the shell is a command line interpreter and interface between the user and the operating system. There are several types of shells are available for the UNIX operating system. Each has similar functionality, but the commands each shell understands are different. Some examples of shells are the Bourne shell (sh), the C shell (csh), the Korn shell (ksh), the Bourne Again shell (bash). The shell is defined within their own set of commands and features. If a user wants to find a command, user can type man page, and it will display commands within the report. For instance, if a user wants to learn about the bash shell, type “man bash” at the command prompt. Man or manual page also shows the common parameters for each command. Each shell characters have special meaning within the shell, it maintains the users custom environment, interprets wildcards, and history of the commands provided (Blum & Bresnahan, 2011).
Conclusion
UNIX is not easy for beginners; it is made for users who know about computing. The shell is the command line interpreter and also an interface between the user and the operating system. The important elements of the shell are using a lower case letters, which is highly sensitive and important to execute the program. As like Window operating system, it can use upper and lower case letters without affecting the shell variables environment. It is also good to know a user can type a specific command in the prompt like “man ls,” and it will display the lists command on the page.
The environment is the most important concept of UNIX, which express by environment variables. The system is set by the users or system, yet some are set by the shell that loads to another program. The assign value is a variable, which is a character string. The value could be a text, number, filename, device, or any other type of data-files. The shell has important process to follow to execute the program. The shell will makes sure to check if the file /ect/profile exists. If