libenv-1.0.0

libenv is a library for modifying environment variables under UNIX like operating systems.

Included is a wrapper library called posix_env that implements a POSIX compliant interface to the following functions:

char *getenv(const char *name);

https://pubs.opengroup.org/onlinepubs/9699919799/functions/getenv.html

int setenv(const char *envname, const char *envval, int overwrite);

https://pubs.opengroup.org/onlinepubs/9699919799/functions/setenv.html

int unsetenv(const char *name);

https://pubs.opengroup.org/onlinepubs/9699919799/functions/unsetenv.html

How to use

For libenv, first initialize the library by calling env_init():

#include "libenv.h"


// Mandatory global variable declaration
env_t test_env;


int main(int argc,
         char **argv,
         char **envp)
{
    if (env_init(
                envp,
                &test_env
                ) < 1)
    {
        printf("[main] ERROR: Couldn't initialize environment\n");
        exit(0);
    }

    ...

    /* Use API here (see libenv.h for declarations) */

    ...
}

For posix_env, first initialize the underlying libenv library by calling env_init():

#include <stdio.h>


#include "libenv.h"
#include "posix_env.h"


// Mandatory global variable declaration
env_t posix_env;


int main(int argc,
         char **argv,
         char **envp)
{
    if (env_init(
                envp,
                &posix_env
                ) < 1)
    {
        printf("[main] ERROR: Couldn't initialize environment\n");
        exit(0);
    }

    ...

    /* Use API here (see posix_env.h for declarations):
     *
     *  char *posix_getenv(const char *);
     *  int posix_setenv(const char *, const char *, int);
     *  int posix_unsetenv(const char *);
     *
     * POSIX functions have a prefixed "posix_" to avoid
     * namespace conflicts with system header declarations
     * or definitions.
     *
     */

    ...

}

How to compile

For libenv, include libenv.h and libenv.c in your project and add libenv.c to the compiler invocation:

bash# c99 -o myproject myproject.c libenv.c

Consult the included Makefile in libenv-1.0.0 for a specific example.

For posix_env, include libenv.h, libenv.c, posix_env.h and posix_env.c in your project and add libenv.c and posix_env.c to the compiler invocation:

bash# c99 -o myproject myproject.c libenv.c posix_env.c

Consult the included Makefile in libenv-1.0.0/posix for a specific example.