This is my own shell program, Mav shell (msh), similar to bourne shell (bash), c-shell (csh), or korn shell (ksh). It accepts commands, forks a child process and executes those commands. The shell, like csh or bash, will run and accept commands until the user exits the shell.
- This program prints out a prompt of msh> when it is ready to accept input. It reads a line of input and, if the command given is a supported shell command, it executes the command and displays the output of the command.
- If the command is not supported, the shell prints the invalid command followed by “: Command not found.”
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After each command completes, the program prints the msh> prompt and accepts another line of input.
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Shell will exit with status zero if the command is “quit” or “exit”.
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If the user types a blank line, the shell quietly prints another prompt and accepts a new line of input.
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Mav shell supports up to 10 command line parameters in addition to the command.
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The shell supports and executes commands located in /bin, /usr/bin, /usr/local/bin, and the current working directory.
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Mav shell is implemented using fork(), wait(), and one of the exec family of functions.
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The shell supports the
cdcommand to change directories and handlescd ...
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The shell saves the last 50 commands and command line parameters.
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The shell prints the history log, excluding blank line entries, when the user types
history.
msh> history
[1] ls
[2] mkdir foo
[3] cd foo
[4] cd ..
[5] history
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The user re-runs any command in the history by typing
!#, where#is the number of the command to rerun. -
The shell supports redirection. The syntax
[process] > [file]redirects the process’s standard output to a file. -
The shell supports pipes between programs.
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The program blocks the SIGINT and SIGTSTP signals.