Write a beautiful code that passes the Betty checks Repo: GitHub repository: simple_shell 1. Simple shell 0.1 mandatory Write a UNIX command line interpreter. Usage: simple_shell Your Shell should: Display a prompt and wait for the user to type a command. A command line always ends with a new line. The prompt is displayed again each time a command has been executed. The command lines are simple, no semicolons, no pipes, no redirections or any other advanced features. The command lines are made only of one word. No arguments will be passed to programs. If an executable cannot be found, print an error message and display the prompt again. Handle errors. You have to handle the “end of file” condition (Ctrl+D) You don’t have to: use the PATH implement built-ins handle special characters : ", ', `, \, *, &, # be able to move the cursor handle commands with arguments julien@ubuntu:~/shell$ ./shell #cisfun$ ls ./shell: No such file or directory #cisfun$ /bin/ls barbie_j env-main.c exec.c fork.c pid.c ppid.c prompt prompt.c shell.c stat.c wait env-environ.c exec fork mypid ppid printenv promptc shell stat test_scripting.sh wait.c #cisfun$ /bin/ls -l ./shell: No such file or directory #cisfun$ ^[[D^[[D^[[D ./shell: No such file or directory #cisfun$ ^[[C^[[C^[[C^[[C ./shell: No such file or directory #cisfun$ exit ./shell: No such file or directory #cisfun$ ^C julien@ubuntu:~/shell$ echo "/bin/ls" | ./shell #cisfun$ barbie_j env-main.c exec.c fork.c pid.c ppid.c prompt prompt.c shell.c stat.c wait env-environ.c exec fork mypid ppid printenv promptc shell stat test_scripting.sh wait.c #cisfun$ julien@ubuntu:~/shell$ Repo: GitHub repository: simple_shell 2. Simple shell 0.2 mandatory Simple shell 0.1 + Handle command lines with arguments Repo: GitHub repository: simple_shell 3. Simple shell 0.3 mandatory Simple shell 0.2 + Handle the PATH fork must not be called if the command doesn’t exist julien@ubuntu:~/shell$ ./shell_0.3 :) /bin/ls barbie_j env-main.c exec.c fork.c pid.c ppid.c prompt prompt.c shell_0.3 stat test_scripting.sh wait.c env-environ.c exec fork mypid ppid printenv promptc shell shell.c stat.c wait :) ls barbie_j env-main.c exec.c fork.c pid.c ppid.c prompt prompt.c shell_0.3 stat test_scripting.sh wait.c env-environ.c exec fork mypid ppid printenv promptc shell shell.c stat.c wait :) ls -l /tmp total 20 -rw------- 1 julien julien 0 Dec 5 12:09 config-err-aAMZrR drwx------ 3 root root 4096 Dec 5 12:09 systemd-private-062a0eca7f2a44349733e78cb4abdff4-colord.service-V7DUzr drwx------ 3 root root 4096 Dec 5 12:09 systemd-private-062a0eca7f2a44349733e78cb4abdff4-rtkit-daemon.service-ANGvoV drwx------ 3 root root 4096 Dec 5 12:07 systemd-private-062a0eca7f2a44349733e78cb4abdff4-systemd-timesyncd.service-CdXUtH -rw-rw-r-- 1 julien julien 0 Dec 5 12:09 unity_support_test.0 :) ^C julien@ubuntu:~/shell$ Repo: GitHub repository: simple_shell 4. Simple shell 0.4 mandatory Simple shell 0.3 + Implement the exit built-in, that exits the shell Usage: exit You don’t have to handle any argument to the built-in exit Repo: GitHub repository: simple_shell 5. Simple shell 1.0 mandatory Simple shell 0.4 + Implement the env built-in, that prints the current environment julien@ubuntu:~/shell$ ./simple_shell $ env USER=julien LANGUAGE=en_US SESSION=ubuntu COMPIZ_CONFIG_PROFILE=ubuntu SHLVL=1 HOME=/home/julien C_IS=Fun_:) DESKTOP_SESSION=ubuntu LOGNAME=julien TERM=xterm-256color PATH=/home/julien/bin:/home/julien/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin DISPLAY=:0 $ exit julien@ubuntu:~/shell$ Repo: GitHub repository: simple_shell 6. Simple shell 0.1.1 #advanced Simple shell 0.1 + Write your own getline function Use a buffer to read many chars at once and call the least possible the read system call You will need to use static variables You are not allowed to use getline You don’t have to: be able to move the cursor Repo: GitHub repository: simple_shell 7. Simple shell 0.2.1 #advanced Simple shell 0.2 + You are not allowed to use strtok Repo: GitHub repository: simple_shell 8. Simple shell 0.4.1 #advanced Simple shell 0.4 + handle arguments for the built-in exit Usage: exit status, where status is an integer used to exit the shell julien@ubuntu:~/shell$ ./shell_0.4.1 $ exit 98 julien@ubuntu:~/shell$ echo $? 98 julien@ubuntu:~/shell$ Repo: GitHub repository: simple_shell 9. setenv, unsetenv #advanced Simple shell 1.0 + Implement the setenv and unsetenv builtin commands setenv Initialize a new environment variable, or modify an existing one Command syntax: setenv VARIABLE VALUE Should print something on stderr on failure unsetenv Remove an environment variable Command syntax: unsetenv VARIABLE Should print something on stderr on failure Repo: GitHub repository: simple_shell 10. cd #advanced Simple shell 1.0 + Implement the builtin command cd: Changes the current directory of the process. Command syntax: cd [DIRECTORY] If no argument is given to cd the command must be interpreted like cd $HOME You have to handle the command cd - You have to update the environment variable PWD when you change directory man chdir, man getcwd Repo: GitHub repository: simple_shell 11. ; #advanced Simple shell 1.0 + Handle the commands separator ; alex@~$ ls /var ; ls /var backups cache crash lib local lock log mail metrics opt run spool tmp backups cache crash lib local lock log mail metrics opt run spool tmp alex@~$ ls /hbtn ; ls /var ls: cannot access /hbtn: No such file or directory backups cache crash lib local lock log mail metrics opt run spool tmp alex@~$ ls /var ; ls /hbtn backups cache crash lib local lock log mail metrics opt run spool tmp ls: cannot access /hbtn: No such file or directory alex@~$ ls /var ; ls /hbtn ; ls /var ; ls /var backups cache crash lib local lock log mail metrics opt run spool tmp ls: cannot access /hbtn: No such file or directory backups cache crash lib local lock log mail metrics opt run spool tmp backups cache crash lib local lock log mail metrics opt run spool tmp alex@~$ Repo: GitHub repository: simple_shell 12. && and || #advanced Simple shell 1.0 + Handle the && and || shell logical operators alex@~$ ls /var && ls /var backups cache crash lib local lock log mail metrics opt run spool tmp backups cache crash lib local lock log mail metrics opt run spool tmp alex@~$ ls /hbtn && ls /var ls: cannot access /hbtn: No such file or directory alex@~$ ls /var && ls /var && ls /var && ls /hbtn backups cache crash lib local lock log mail metrics opt run spool tmp backups cache crash lib local lock log mail metrics opt run spool tmp backups cache crash lib local lock log mail metrics opt run spool tmp ls: cannot access /hbtn: No such file or directory alex@~$ ls /var && ls /var && ls /var && ls /hbtn && ls /hbtn backups cache crash lib local lock log mail metrics opt run spool tmp backups cache crash lib local lock log mail metrics opt run spool tmp backups cache crash lib local lock log mail metrics opt run spool tmp ls: cannot access /hbtn: No such file or directory alex@~$ alex@~$ ls /var || ls /var backups cache crash lib local lock log mail metrics opt run spool tmp alex@~$ ls /hbtn || ls /var ls: cannot access /hbtn: No such file or directory backups cache crash lib local lock log mail metrics opt run spool tmp alex@~$ ls /hbtn || ls /hbtn || ls /hbtn || ls /var ls: cannot access /hbtn: No such file or directory ls: cannot access /hbtn: No such file or directory ls: cannot access /hbtn: No such file or directory backups cache crash lib local lock log mail metrics opt run spool tmp alex@~$ ls /hbtn || ls /hbtn || ls /hbtn || ls /var || ls /var ls: cannot access /hbtn: No such file or directory ls: cannot access /hbtn: No such file or directory ls: cannot access /hbtn: No such file or directory backups cache crash lib local lock log mail metrics opt run spool tmp alex@~$ Repo: GitHub repository: simple_shell 13. alias #advanced Simple shell 1.0 + Implement the alias builtin command Usage: alias [name[='value'] ...] alias: Prints a list of all aliases, one per line, in the form name='value' alias name [name2 ...]: Prints the aliases name, name2, etc 1 per line, in the form name='value' alias name='value' [...]: Defines an alias for each name whose value is given. If name is already an alias, replaces its value with value Repo: GitHub repository: simple_shell 14. Variables #advanced Simple shell 1.0 + Handle variables replacement Handle the $? variable Handle the $$ variable julien@ubuntu:~/shell$ ./hsh $ ls /var backups cache crash lib local lock log mail metrics opt run snap spool tmp $ echo $? 0 $ echo $$ 5104 $ echo $PATH /home/julien/bin:/home/julien/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin $ exit julien@ubuntu:~/shell$ Repo: GitHub repository: simple_shell 15. Comments #advanced Simple shell 1.0 + Handle comments (#) julien@ubuntu:~/shell$ sh $ echo $$ # ls -la 5114 $ exit julien@ubuntu:~/shell$ Repo: GitHub repository: simple_shell 16. File as input #advanced Simple shell 1.0 + Usage: simple_shell [filename] Your shell can take a file as a command line argument The file contains all the commands that your shell should run before exiting The file should contain one command per line In this mode, the shell should not print a prompt and should not read from stdin Repo: GitHub repository: simple_shell