// ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
//
//  Copyright (c) 2001-2003, Haiku
//
//  This software is part of the Haiku distribution and is covered
//  by the MIT License.
//
//
//  File:        printenv.c
//  Author:      Daniel Reinhold (danielre@users.sf.net)
//  Description: prints environment variables
//
// ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

#include <OS.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>


extern char **environ;

int print_env(char *);


int
main(int argc, char *argv[])
{
        char *arg = (argc == 2 ? argv[1] : NULL);
        
        if ((argc > 2) || (arg && !strcmp(arg, "--help"))) {
                printf("Usage: printenv [VARIABLE]\n"
                       "If no environment VARIABLE is specified, print them all.\n");
                return 1;
        }
        
        return print_env(arg);
}


int
print_env(char *arg)
{
        char **env = environ;
        
        if (arg == NULL) {
                // print all environment 'key=value' pairs (one per line)
            while (*env)
                        printf("%s\n", *env++);
                
                return 0;
        } else {
                // print only the value of the specified variable
                char *s;
                int   len   = strlen(arg);
                bool  found = false;
                
            while ((s = *env++) != NULL)
                if (!strncmp(s, arg, len)) {
                        char *p = strchr(s, '=');
                        if (p) {
                                        printf("%s\n", p+1);
                                        found = true;
                                }
                        }
                
                return (found ? 0 : 1);
        }
}