Page 134 - DCAP106_OPERATING_SYSTEM_TOOLS

Unit 7: The Shell

z z TCSH is a command language interpreter usable both as an interactive login shell and a Notes
shell script command processor.
z z Internal commands are those which are directly executed by the shell. External commands
are files present in the $PATH.

7.5 Keywords

Arguments: Arguments are the values you pass to a shell script.

BASH: BASH is a free software UNIX shell written for the GNU Project.
csh: The C shell (csh) is a Unix shell which added many feature improvements over the Bourne
shell, such as aliases and command history.

External commands: External commands are files present in the $PATH.
Internal commands: Internal commands are those which are directly executed by the shell.
ksh: The Korn shell (ksh) is a Unix shell which is backwards-compatible with the Bourne shell
and includes many features of the C shell as well.

Shell: The shell is an executable file responsible for interpreting the commands, transmitting
them to the system, and returning the result.
TCSH: TCSH is a command language interpreter usable both as an interactive login shell and a
shell script command processor.
Variable: A variable in a shell script is a means of referencing a numeric or character value.

7.6 Review Questions

1. Explain how shell acts as an intermediary between the operating system and the user.
2. Describe the concept of shell variables with example.

3. Make distinction between single quotation marks and double quotation marks.
4. What are the different types of shell? Explain.
5. Compare and contrast C shell and Korn shell.
6. TCSH is a command language interpreter usable both as an interactive login shell and a
shell script command processor. Comment.
7. What are the built-in programs in Linux? Discuss.
8. Illustrate the difference between internal and external commands.

9. Discuss some special variables that are useful in script writing.
10. Explain the features of Korn Shell.

Answers: Self Assessment

1. Shell 2. Root
3. command line 4. Variable
5. backslash 6. Bash
7. C shell (csh) 8. Korn

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