• Two files are provided – shell.I and argshell.c (argshell.c is the one that you need to work in)
• Shell.I is a parser. To compile it, do:
% flex shell.I
• Need to compile and link your code and parser together! % cc –o argshell argshell.c lex.yy.c -lfl
• Argument after “-o” is the running program name. Now to run the program, do:
% ./argshell
Running the Program
• $ ./argshell
Command ('exit' to quit): ls -l
Argument 0: ls
Argument 1: -l
total 140
-rwxr-xr-x 1 hcasalet wheel
25930 Jan
6 12:12 argshell
-rw-r--r-- 1 hcasalet wheel
2140 Jan 6 00:05 argshell.c
-rw-------
1 hcasalet wheel 4644864 Jan 5 23:51 argshell.core
-rwxr-xr-x 1 hcasalet wheel
25124 Jan
5 12:14 argshell.o
-rw-r--r-- 1 hcasalet wheel
45083 Jan 5 11:22 lex.yy.c
-rwxr-xr-x 1 hcasalet wheel
25025 Jan
5 11:31 lex.yy.o
-rw-r--r-- 1 hcasalet wheel
707 Jan 5
10:53 shell.l
Command ('exit' to quit): exit
Argument 0: exit
Exiting...
$
The Rubric
• Code needs to be pushed to Git in order to get credit. Make sure that your code compiles!
• First project is individual project, rest of them are done in groups of size two. A captain is selected for each group. Only captains push code to Git.
• Captains need to give access to team members:
% ssh git@git.soe.ucsc.edu/..../captain_cruzid +WRITERS team_member_cruzid
• Team members then git clone from their captains
git clone git@gitlab.soe.ucsc.edu:cmps111/fall18-01/[CRUZID].git
The Rubric (continued)
• Git commands review
• git add, git commit, git push
• Need to write:
• A design doc – How you design your shell
• A readme file – To let users of your shell to know how to use it
• A make file – an OS tool to help simplify building running program. Example:
build an executable named myprog from myprog.c all: myshell.c
(tab) cc -o myshell myshell.c clean:
(tab) $(RM) myshell
Make sure that your Makefile works!
• All the above, along with your code, need to be pushed into Git.
Unix Shell in FreeBSD
• Shell - User interface to gain accesses to the services provided by the Operating System
• Could be Command Line Interface, or Graphic User Interface • Shell interprets user commands, and makes system calls. • Shells in FreeBSD
• Tcsh - Default shell
• Bourne shell available to install (pkg install bash)
System Calls
• What is a system call? – A way for programs to communicate with the Operating System.
• When to make a system call? – when programs request services from the kernel.
• Types of system calls:
• Process management
• Memory allocation and management
• File access
• Device manipulation
• Protection
• Communication
• And more
System calls (continued)
• Process Management - fork(), wait(), exit(), execvp()
• File Access – open(), close(), dup(), dup2()
• Communication – pipe()
• Directory Management – chdir(), getcwd()
