Get Home Directory on Linux

Question

I need a way to get the user's home directory in a C ++ program running on Linux. If the same code works on Unix, it would be nice. I do not want to use the value of the HOME environment.

AFAIK, the root home directory is / root. Can I create several files / folders in this directory if my program is run as root?

Answer 1

You need getuid to get the user id of the current user, and then getpwuid to get the password entry (including the home directory) of this user:

 #include <unistd.h> #include <sys/types.h> #include <pwd.h> struct passwd *pw = getpwuid(getuid()); const char *homedir = pw->pw_dir; 

Note. If you need this in a streaming application, you will want to use getpwuid_r instead.

Answer 2

You must check the $HOME environment variable first, and if it does not exist, use getpwuid.

 #include <unistd.h> #include <sys/types.h> #include <pwd.h> const char *homedir; if ((homedir = getenv("HOME")) == NULL) { homedir = getpwuid(getuid())->pw_dir; } 

Also note that if you want the home directory to save configuration data or cache as part of the program that you write and want to distribute to users, you should consider complying with the XDG Base Directory specification . For example, if you want to create a configuration directory for your application, you must first check $XDG_CONFIG_HOME using getenv as shown above, and return to the code above only if the variable is not set.

If you require multi-threaded security, you should use getpwuid_r instead of getpwuid as follows (from the getpwnam(3) page):

 struct passwd pwd; struct passwd *result; char *buf; size_t bufsize; int s; bufsize = sysconf(_SC_GETPW_R_SIZE_MAX); if (bufsize == -1) bufsize = 0x4000; // = all zeroes with the 14th bit set (1 << 14) buf = malloc(bufsize); if (buf == NULL) { perror("malloc"); exit(EXIT_FAILURE); } s = getpwuid_r(getuid(), &pwd, buf, bufsize, &result); if (result == NULL) { if (s == 0) printf("Not found\n"); else { errno = s; perror("getpwnam_r"); } exit(EXIT_FAILURE); } char *homedir = result.pw_dir; 

Answer 3

If you use the program as root, then you will have access to rwx in this directory. Creating the material inside it is fine, I suppose.