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.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌────────────────────────────┬───────────────┬─────────┐
       │Interface                   │ Attribute     │ Value   │
       ├────────────────────────────┼───────────────┼─────────┤
       │envz_add(), envz_entry(),   │ Thread safety │ MT-Safe │
       │envz_get(), envz_merge(),   │               │         │
       │envz_remove(), envz_strip() │               │         │
       └────────────────────────────┴───────────────┴─────────┘

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 4.15 of the Linux man-pages project.  A  description  of  the
       project,  information  about  reporting  bugs, and the latest version of this page, can be
       found at https://www.kernel.org/doc/man-pages/.

                                            2017-09-15                                ENVZ_ADD(3)