tphuong141607 / Shell-Implementation

The sushi SHELL provides some real SHELL's basic functionalities

yesCODE--Shell Implementation

This implemented shell is created in March, 2019.

The shell provides some real shell's basic functionalities such as:

1. Validate, store and save commands from the command line/terminal to history. Check the history my typing !

2. The ability to start other programs

3. Background and foreground execution, memory cleanup, and environment management

4. Software pipes:

Shell expression A | B means that the standard output of process A is redirected through a pipe to the standard input of process B. Neither process “knows” that the I/O’s have been reconnected.

The code of A or B has not been modified. Pipes can be chained potentially indefinitely: A | B | C | … | Z. This core Unix/Linux construct is called “pipes and filters” architecture, where data is treated as fluid and processes filter and modify it as it flows through them.

5. Shell script support

A shell can be used as a script interpreter. If any parameters are passed to the shell via argv, they shall be treated as file names.

6. Shell prompt

The shell prompt is controlled by the environmental variable $PS1, you can change the environmental variable by setting PS1 = Your desire name.

7. Input/output redirection

The following command line reads file sushi.c with cat, counts the number of lines in the file with wc -l, and appends the results to the end of lines.txt. If the latter file does not exist, it is first created: cat < sushi.c | wc -l >> lines.txt

8. Change the current working directory using cd

9. Show the current working directory using pwd