2 nd Assignment  Improve Toyshell with some new feature, such as: help, cd, ctrl/D, setenv and compile it. Create a user “lapsa” and make him to get Toyshell upon login.  Write 4 small shell scripts specified  Explain some Unix shell script (e.g. some strat-up sequence script) with total length >30 lines What is the role of this script in the Unix system? Comment the contents of the script line by line  (Optional): replace Unix “init” program with some other program (e.g. shell) and manually bring the system to usable state Record your manual steps into a shell-script and use it to initialize the system automatically after restart (without the classic “init”)

Submission  Name your submission JanisBerzins.zip  Name shell scripts 1.sh, 2.sh, 3.sh, 4.sh To ease their automatic verification by teacher

Technical info  Recommended is Bash; if you use a different shell language, make sure that we will be able to run it  Scripts can use external “helper” programs, but do not use any exotics that the testing system might not have  Scripts must not ask for any other input than specified or pause as they may be tested automatically  Of course, no abuse attempts  Toyshell can be (optionally) improved with fragments from file found under 4. lekcija – “ Noderīgi progr.fragmentu paraugi” or by looking at some real shell source code

1.sh  Create script, that automatically writes “hello world” to standard output deletes file “deleteme.txt” creates directory “new_dir” in the working directory writes the output of “date” command to file “date.txt” inside the “new_dir” directory

2.sh  File “a” will contain one number 0 <= A <= 100  File “b” will contain one number 0 <= B <= 100  Create Bash script, that will read inputs from files and create file “c” containing number A*B (A multiplied by B)  Example: If file “a” contains “4”, file “b” contains “5”, and “./2.sh” is run, file “c” should contain “20”.

3.sh  Create script, that will take 2 arguments: 3.sh  Search the files in for substring “moveme” in the file content  Move those files that contain the string to directory  On the standard output, output two lines: On first line, output the total number of lines that matched On second line, output the total number of files moved

4.sh  Create a number guessing game, that “thinks” of a number N in the range of and makes the user guess it  Read user’s guess (internal command read )  After successful attempt, show victory message and exit  After unsuccessful attempt, show number of tries left, and whether the number guessed is larger or smaller than N  If 10 tries are made, display N and exit

#include #define MAXLINE 200 #define MAXARG 20 extern char **environ; void env(void){ int i; for(i=0;environ[i]!=NULL;i++){ printf("%s\n",environ[i]); } void exitsh(int status){ _exit(status); } void execute(char *arg[]){ pid_t pid; int status; pid=fork(); if(pid>0){ wait(&status); } else if (pid==0) { execvp(arg[0],arg); printf("Komanda nav atrasta\n"); exitsh(0); } else { printf("Kluda fork() sistemas izsaukuma\n"); } int main (void){ char cmd[MAXLINE]; char *cmdp; char *av[MAXARG]; int i; while(1){ printf("$toyshell$> "); fgets(cmd,sizeof(cmd),stdin); if(strcmp(cmd,"env\n")==0){ env(); } else if(strcmp(cmd,"exit\n")==0){ exitsh(0); } else { cmdp=cmd; for(i=0;i<MAXARG;i++){ av[i]=strtok(cmdp," \t\n"); cmdp=NULL; } execute(av); } return(0); } toyshell.c

“toyshell” palaišana # /usr/bin/gcc toyshell.c # cc toyshell.c #./a.out $toyshell$> env USER=root HOME=/root TERM=vt100 PATH=/root/bin:/usr/local/bin:/bin:/usr/bin SHELL=/bin/sh $toyshell$> ps PID TTY TIME CMD 126 co 0:00 -sh 95 c1 0:00 getty 435 p1 0:00./a.out 436 p1 0:00 ps $toyshell$> exit #