Myshell is a simple implementation of Linux terminal. It takes commands and arguments and execute them if they are available.
When it starts, it takes your PC's path details and search the executable in these areas,
if successful it runs it with the given arguments.
Also it allows background processes. If you put a "&" sign at the end of line (like Unix), it runs the program in the background.
But its log is still in main process. Whenever you type "fg" it brings all background processes to the foreground.
Also there are some commands built-in:
1 -) alias/unalias
- If you want your long string of executable string shrink into a smaller string, you can use alias.
Ex: alias "ls -l" list --- Whenever you type list, myshell will run "ls -l"
- You can see all aliases recorded.
alias -l
- Also you can unalias your aliases by using unalias.
Ex: unalias list
2 -) If you press ^z while a foreground process is running, that process will go to the background.
3 -) clr - this command does the same thing with the "clear" command.
4 -) fg
- This command brings all background processes to the foreground one by one.
5 -) exit
- This command is the only way to exit the program safely. But it won't let you exit if there are any background processes.
Another feature of this shell is input/output redirection. There are a few ways to accomplish this:
myprog [args] > file.out// myprog's standard output is redirected to the file.out. Overwrites the file if exists.myprog [args] >> file.out// myprog's standard output is appended to the file.out.myprog [args] < file.in// uses file.in as the standard input of myprog.myprog [args] 2> file.out// myprog's standard error channel is redirected to the file.out.
** Also you can use input and output in one line interchangeably.
myprog [args] < file.in > file.out// uses file.in as the standard input of myprog and myprog's standard output is redirected to the file.out.
This is a multiprocess program. Whenever an executable is wanted, it forks a child and executes the program in that process.