Victor Frenkel
vgf2103
Operating Systems HW 1
README


FILES/DESCRIPTIONS:

hw1
.
├── Makefile <<-- controls compilation
├── README <<-- this document, describing the project.
├── shell.c <<-- most of the shell's core functionality is implemented here.
├── shell.h <<-- a header interface to some of the functions in shell.c (exposes functions to shell_main.c but also used for testing)
├── shell_main.c <<-- the main shell prompt loop, also containing logic to catch the built-in commands.
├── sllist.c <<-- singly linked list implementation.
├── sllist.h <<-- singly linked list implementation header.
└── vgf2103_written_part.txt <<-- the written part of this homework.

0 directories, 8 files

COMPILE INSTRUCTIONS:

type 'make'. will compile and link the myshell executable.


TEST RUN:

This is a demo of my shell's functionality. Includes a valgrind memory report at the end of the session. Tested on machine Warsaw in the clic lab.


vgf2103@warsaw /home/vgf2103/ACADEMIC/os/hw1 $ ./myshell

/home/vgf2103/ACADEMIC/os/hw1 $ ls
Makefile  myshell  shell.c  shell.h  shell_main.c  shell_main.o  shell.o  sllist.c  sllist.h  sllist.o  vgf2103_written_part.txt
/home/vgf2103/ACADEMIC/os/hw1 $ mkdir tests               
/home/vgf2103/ACADEMIC/os/hw1 $ ls
Makefile  myshell  shell.c  shell.h  shell_main.c  shell_main.o  shell.o  sllist.c  sllist.h  sllist.o  tests  vgf2103_written_part.txt
/home/vgf2103/ACADEMIC/os/hw1 $ cd tests
/home/vgf2103/ACADEMIC/os/hw1/tests $ ls
/home/vgf2103/ACADEMIC/os/hw1/tests $ pwd
/home/vgf2103/ACADEMIC/os/hw1/tests
/home/vgf2103/ACADEMIC/os/hw1/tests $ cp /usr/bin/echo myecho
cp: cannot stat `/usr/bin/echo': No such file or directory
/home/vgf2103/ACADEMIC/os/hw1/tests $ cp /bin/echo myecho
/home/vgf2103/ACADEMIC/os/hw1/tests $ ls
myecho
/home/vgf2103/ACADEMIC/os/hw1/tests $ myecho hi how are you?
hi how are you?
/home/vgf2103/ACADEMIC/os/hw1/tests $ myecho hello | cat | cat
hello
/home/vgf2103/ACADEMIC/os/hw1/tests $ myecho this is another pipeline test | wc
      1       5      30
/home/vgf2103/ACADEMIC/os/hw1/tests $ echo i loves kitties. > kitties.txt
/home/vgf2103/ACADEMIC/os/hw1/tests $ cat kitties.txt
i loves kitties.
/home/vgf2103/ACADEMIC/os/hw1/tests $ ls
kitties.txt  myecho
/home/vgf2103/ACADEMIC/os/hw1/tests $ path
/bin:/usr/bin
/home/vgf2103/ACADEMIC/os/hw1/tests $ path + /home/vgf2103
/home/vgf2103/ACADEMIC/os/hw1/tests $ path
/bin:/usr/bin:/home/vgf2103
/home/vgf2103/ACADEMIC/os/hw1/tests $ path + /home/vgf2103/
/home/vgf2103/ACADEMIC/os/hw1/tests $ path
/bin:/usr/bin:/home/vgf2103:/home/vgf2103
/home/vgf2103/ACADEMIC/os/hw1/tests $ path - /bin     
/home/vgf2103/ACADEMIC/os/hw1/tests $ path
/usr/bin:/home/vgf2103:/home/vgf2103
/home/vgf2103/ACADEMIC/os/hw1/tests $ path - /home/vgf2103
/home/vgf2103/ACADEMIC/os/hw1/tests $ path
/usr/bin
/home/vgf2103/ACADEMIC/os/hw1/tests $ path + /bin
/home/vgf2103/ACADEMIC/os/hw1/tests $ path
/usr/bin:/bin
/home/vgf2103/ACADEMIC/os/hw1/tests $ path - /bin
/home/vgf2103/ACADEMIC/os/hw1/tests $ path
/usr/bin
/home/vgf2103/ACADEMIC/os/hw1/tests $ echo can not find this now
error: not a valid command.
/home/vgf2103/ACADEMIC/os/hw1/tests $ path + /bin
/home/vgf2103/ACADEMIC/os/hw1/tests $ echo i can find it now
i can find it now
/home/vgf2103/ACADEMIC/os/hw1/tests $ path
/usr/bin:/bin
/home/vgf2103/ACADEMIC/os/hw1/tests $ cat < kitties.txt
i loves kitties.
/home/vgf2103/ACADEMIC/os/hw1/tests $ cat < kitties.txt > kitty_dup.txt 2> errorz.txt
/home/vgf2103/ACADEMIC/os/hw1/tests $ ls
errorz.txt  kitties.txt  kitty_dup.txt  myecho
/home/vgf2103/ACADEMIC/os/hw1/tests $ cat errorz.txt
/home/vgf2103/ACADEMIC/os/hw1/tests $ cat kitty_dup.txt
i loves kitties.
/home/vgf2103/ACADEMIC/os/hw1/tests $ cat kitties.txt
i loves kitties.
/home/vgf2103/ACADEMIC/os/hw1/tests $ cat notarealfile 2> errorz.txt
/home/vgf2103/ACADEMIC/os/hw1/tests $ cat errorz.txt
cat: notarealfile: No such file or directory
/home/vgf2103/ACADEMIC/os/hw1/tests $ echo it is time to go feed the kitties > kitties.txt | wc | cat
error: syntax error in output redirection.
/home/vgf2103/ACADEMIC/os/hw1/tests $ echo < kitties.txt | wc | cat          
      1       0       1
/home/vgf2103/ACADEMIC/os/hw1/tests $ echo < kitties.txt

/home/vgf2103/ACADEMIC/os/hw1/tests $ cat < kitties.txt | wc | cat
      1       3      17
/home/vgf2103/ACADEMIC/os/hw1/tests $ cat < kitties.txt | wc
      1       3      17
/home/vgf2103/ACADEMIC/os/hw1/tests $ exit
==10498== 
==10498== HEAP SUMMARY:
==10498==     in use at exit: 0 bytes in 0 blocks
==10498==   total heap usage: 675 allocs, 675 frees, 10,498 bytes allocated
==10498== 
==10498== All heap blocks were freed -- no leaks are possible
==10498== 
==10498== For counts of detected and suppressed errors, rerun with: -v
==10498== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 2 from 2)


ASSUMPTIONS:

Used system defined limits, queried them. Did not have to make assumptions....