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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 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.


     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


     For   an   explanation   of   the  terms  used  in  this  section,  see
     |Interface                   | Attribute     | Value   |
     |envz_add(), envz_entry(),   | Thread safety | MT-Safe |
     |envz_get(), envz_merge(),   |               |         |
     |envz_remove(), envz_strip() |               |         |


     These functions are a GNU extension.  Handle with care.


     #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); }




     This  page  is  part of release 4.16 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
                                2017-09-15                       ENVZ_ADD(3)
/data/webs/external/dokuwiki/data/pages/man/envz_add.txt · Last modified: 2019/05/17 09:47 by

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