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

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

       #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);

       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

       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.

       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.

       These functions are a GNU extension.  Handle with care.

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

       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);


       This page is part of release 3.22 of the Linux man-pages project.  A description of the project,  and  informa-
       tion about reporting bugs, can be found at

                                  2007-05-18                       ENVZ_ADD(3)