| NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | CONFORMING TO | EXAMPLE | SEE ALSO | COLOPHON | The Linux Programming Interface |
ENVZ_ADD(3) Linux Programmer's Manual ENVZ_ADD(3)
envz_add, envz_entry, envz_get, envz_merge, envz_remove, envz_strip - environ-
ment 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 occurs.
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);
}
argz_add(3)
This page is part of release 3.32 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)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface