Manage the environment
#include <env.h>
char **environ;
char *env_get(name);
char *env_pick();
char *name;
The environment, environ, is a 0-terminated array of 0-terminated strings, called environment variables. Each environment variable is of the form name=value.
env_get returns the value of the first variable whose name is name, or 0 if there is no such variable.
env_pick returns any variable in the environment, or 0 if the environment is empty.