UNIX Shell

In Lab$9$ we did the $3$ built$-$in commands: cd$,$ pwd$,$ exit.

Now we need to implement: a fork, an exec, and code to handle redirection.

Makeshift Pictorial of the calling sequence of Lab$10$

main$/$lab$10.$c PS: Box indicates a function.

ParseCmd ProcessExtCmd

Call fork

Parent does Wait Child Process

RunExtCmd

Redirection

Call execvp

FILES TO COPY$-$ Different Instructions this time:

To get the file you need, first move to your class folder by typing: cd csc$60$

Type: cp $-$R $/$home$/$college$/$bielr$/$files$\_$csc$60/$lab$10.$

Spaces needed: $(1)$ After the cp $$ Don$$t miss the space & dot.

$(2)$ After the $-$R

$(3)$ After the directory name at the end & before the dot.

You have now created a lab$10$ directory and copied in Lab$10$ functions:

lab$10.$c$,$ ParseCmd.c$,$ ProcessExtCmd.c$,$ lab$9\_10.$h$,$

RunExtCmd.c$,$ Redirection.c $($These last two are started and you must finish them.$)$

Stay in directory csc$60,$ and you need to

type: chmod $755$ lab$10//$ makes the directory accessible

type: cp lab$9/$lab$9.$c lab$10/$lab$10.$c $//$ copies lab$9.$c into lab$10.$c

CSC $60.$ Fall $2023.$ Lab $10.$ Write your own UNIX Shell, part $2.$

Page $2$ of $8.$

We have copied lab$9$ code and renamed it to lab$10.$c for you to start work on it

Next move to lab$10$ directory by typing: cd lab$10$

and then type: chmod $644*$

This will set permissions on all the files.

Your new lab$10$ directory should now contain:

lab$10.$c$,$ ParseCmd.c$,$ ProcessExtCmd.c$,$ lab$9\_10.$h$,$

RunExtCmd.c$,$ Redirection.c $($These last two are started and you must finish them.