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2017-09-15
Aliases: envz(3), envz(3), envz(3), envz(3), envz(3), envz(3), envz_entry(3), envz_entry(3), envz_entry(3), envz_entry(3), envz_entry(3), envz_entry(3), envz_entry(3), envz_entry(3), envz_get(3), envz_get(3), envz_get(3), envz_get(3), envz_get(3), envz_get(3), envz_get(3), envz_get(3), envz_merge(3), envz_merge(3), envz_merge(3), envz_merge(3), envz_merge(3), envz_merge(3), envz_merge(3), envz_merge(3), envz_remove(3), envz_remove(3), envz_remove(3), envz_remove(3), envz_remove(3), envz_remove(3), envz_remove(3), envz_remove(3), envz_strip(3), envz_strip(3), envz_strip(3), envz_strip(3), envz_strip(3), envz_strip(3), envz_strip(3), envz_strip(3)

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Manual pages about using GNU/Linux for development

man-pages

Linux kernel and C library user-space interface documentation

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 \(aq=\(aq is considered to be the value. If there is no \(aq=\(aq, the value is taken to be NULL. (While the value in case of a trailing \(aq=\(aq 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 \(aq=\(aq 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


Thread safety MT-Safe

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

COLOPHON

This page is part of release 5.00 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/.

REFERENCED BY

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