This implemented shell is created in March, 2019.
1. Validate, store and save commands from the command line/terminal to history. Check the history my typing !
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.
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.
The shell prompt is controlled by the environmental variable $PS1, you can change the environmental variable by setting PS1 = Your desire name
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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