Address Space

What is Copied Over?

Forkbomb

Process Flowchart

All Fork-Exec-Wait Code

pid_t pid = fork();
if(pid == -1){
    //fork failed
}else if(pid == 0){
    //I am the child
    exec(...)
}else{
    //I Am the parent
    wait(pid);
}

Exec Family

• There are three modifiers/mnemonic
  • Either past a list or argv (null terminated array) of arguments
  • Search for the executable either in the current directory or in the path
  • Use the parent’s environment variables or use an environment setting

• Here are the list exec
  • execl( path, arg, … ),execute the file in current directory
  • execlp( file, arg, … ), executes a file only searching in the path
  • execle( path, arg, …, envp[]), execute the file in path + environment settings

• Pass an array of string as arguments
  • execv( path, argv[]), execute the file in current directory
  • execvp( file, argv[]), execute the file in the path only
  • execvpe( file, argv[]), envp[]) // environment setting

time Workflow

Helper Functions

• struct timespec
  • time_t tv_sec;
  • long tv_nsec;
  • tv_sec = 10, tv_nsec = 992300000 -> 10.9923 sec
• int clock_gettime(clockid_t, timespec *);
  • clockid_t: should use CLOCK_MONOTONIC in this lab
• return 0 when success, -1 otherwise

env Workflow

Helper Functions

• int setenv(const char* name, const char* value,
int overwrite)
• char *getenv(const char *name)
• Write a split function that can split string based on ,
• Write a function that can find all %notation in a string
• Extend that function so that you can replace variables
  with environment variables
• Use getenv to get environment variables
• Be familiar with: return array of strings, clear an array
  of strings-> camelCasers