src/bin/printenv.c

   1 // ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
   2 //
   3 //  Copyright (c) 2001-2003, OpenBeOS
   4 //
   5 //  This software is part of the OpenBeOS distribution and is covered
   6 //  by the MIT License.
   7 //
   8 //
   9 //  File:        printenv.c
  10 //  Author:      Daniel Reinhold (danielre@users.sf.net)
  11 //  Description: prints environment variables
  12 //
  13 // ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
  14
  15 #include <OS.h>
  16 #include <stdio.h>
  17 #include <stdlib.h>
  18 #include <string.h>
  19
  20
  21 extern char **environ;
  22
  23 int print_env(char *);
  24
  25
  26 int
  27 main(int argc, char *argv[])
  28 {
  29         char *arg = (argc == 2 ? argv[1] : NULL);
  30
  31         if ((argc > 2) || (arg && !strcmp(arg, "--help"))) {
  32                 printf("Usage: printenv [VARIABLE]\n"
  33                        "If no environment VARIABLE is specified, print them all.\n");
  34                 return 1;
  35         }
  36
  37         return print_env(arg);
  38 }
  39
  40
  41 int
  42 print_env(char *arg)
  43 {
  44         char **env = environ;
  45
  46         if (arg == NULL) {
  47                 // print all environment 'key=value' pairs (one per line)
  48             while (*env)
  49                         printf("%s\n", *env++);
  50
  51                 return 0;
  52         } else {
  53                 // print only the value of the specified variable
  54                 char *s;
  55                 int   len   = strlen(arg);
  56                 bool  found = false;
  57
  58             while ((s = *env++) != NULL)
  59                 if (!strncmp(s, arg, len)) {
  60                         char *p = strchr(s, '=');
  61                         if (p) {
  62                                         printf("%s\n", p+1);
  63                                         found = true;
  64                                 }
  65                         }
  66
  67                 return (found ? 0 : 1);
  68         }
  69 }