ENVZ_ADD(3)                                         Linux Programmer's Manual                                        ENVZ_ADD(3)



NAME
       envz_add, envz_entry, envz_get, envz_merge, envz_remove, envz_strip - environment string support

SYNOPSIS
       #include <envz.h>

       error_t envz_add(char **envz, size_t *envz_len,
                    const char *name, const char *value);

       char *envz_entry(const char *envz, size_t *envz_len, const char *name);

       char *envz_get(const char *envz, size_t *envz_len, const char *name);

       error_t envz_merge(char **envz, size_t *envz_len,
                    const char *envz2, size_t envz2_len, int override);

       void envz_remove(char **envz, size_t *envz_len, const char *name);

       void envz_strip(char **envz, size_t *envz_len);

DESCRIPTION
       These functions are glibc-specific.

       An  argz  vector is a pointer to a character buffer together with a length, see argz_add(3).  An envz vector is a special
       argz vector, namely one where the strings have the form "name=value".  Everything after the first '=' is considered to be
       the  value.   If there is no '=', the value is taken to be NULL.  (While the value in case of a trailing '=' is the empty
       string "".)

       These functions are for handling envz vectors.

       envz_add() adds the string "name=value" (in case value is non-NULL) or "name" (in case value is NULL) to the envz  vector
       (*envz, *envz_len) and updates *envz and *envz_len.  If an entry with the same name existed, it is removed.

       envz_entry() looks for name in the envz vector (envz, envz_len) and returns the entry if found, or NULL if not.

       envz_get() looks for name in the envz vector (envz, envz_len) and returns the value if found, or NULL if not.  (Note that
       the value can also be NULL, namely when there is an entry for name without '=' sign.)

       envz_merge() adds each entry in envz2 to *envz, as if with envz_add().  If override is true, then values  in  envz2  will
       supersede those with the same name in *envz, otherwise not.

       envz_remove() removes the entry for name from (*envz, *envz_len) if there was one.

       envz_strip() removes all entries with value NULL.

RETURN VALUE
       All  envz  functions  that do memory allocation have a return type of error_t, and return 0 for success, and ENOMEM if an
       allocation error occurs.

CONFORMING TO
       These functions are a GNU extension.  Handle with care.

EXAMPLE
       #include <stdio.h>
       #include <stdlib.h>
       #include <envz.h>

       int
       main(int argc, char *argv[], char *envp[])
       {
           int i, e_len = 0;
           char *str;

           for (i = 0; envp[i] != NULL; i++)
               e_len += strlen(envp[i]) + 1;

           str = envz_entry(*envp, e_len, "HOME");
           printf("%s\n", str);
           str = envz_get(*envp, e_len, "HOME");
           printf("%s\n", str);
           exit(EXIT_SUCCESS);
       }

SEE ALSO
       argz_add(3)

COLOPHON
       This page is part of release 3.25 of the Linux man-pages project.  A description of the project,  and  information  about
       reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



                                                           2007-05-18                                                ENVZ_ADD(3)