c - Are these strings concatenated correctly for fopen()? -

i want concatenate 2 strings config_path , config_file , pass string fopen(). problem fopen() returns error though 100% file exists. matter of fact, print string in command line before passing fopen(), , if copy string directly source code, fopen() finds file. what's problem here?

command line output

config: /nfs/stak/students/m/morriluk/.myshellrc|header: home unable open configuration file: no such file or directory 

source code

  1 #define _posix_c_source 200908l   2 #define shell_bsize 1024   3 #define bsize 128   4 #define config_file "/.myshellrc"   5   6 #include <stdio.h>   7 #include <stdlib.h>   8 #include <string.h>   9 #include <dirent.h>  10 #include <unistd.h>  11 #include <errno.h>  12 #include <sys/types.h>  13 #include <sys/wait.h>  14  15 char *warnings = "0";  16  17 int main()  18 {  19     int i;  20     char buffer[bsize], *arg = null;  21     file *f;  22     char *config_path, *str, *config_file = config_file;  23     char *header = "home";  24  25     config_path = getenv("home");  26  27     str = malloc((strlen(config_path)+strlen(config_file))*sizeof(char));  28     strcpy(str, config_path);  29     strcat(str, config_file);  30  31     printf("config: %s|header: %s\n", str, header);  32  33     (i = 0; < bsize; i++)  34         buffer[i] = '\0';  35  36     if ((f = fopen(str, "r")) != null){  37  38     }  39     else {  40         perror("unable open configuration file");  41     }  42     return 0;  43 } 

example program open file getting path env

openfile() { string filename; file      *fp; filename = string(getenv("home")) + "/filename"; //home - configpath, replace file name fp = fopen(filename, "r"); if (fp == null ) cout<<"filename read failed"<<endl; /* write code perform task on file */ fclose(fp); //close handle  } 

to test can make random file , try if fopen works other file in same path

if(fp=fopen("/nfs/stak/students/m/morriluk/testfile","r")) 

if above code not solve problem, let me know unix flavor , absolute file path name