GETENV

Section: C Library Functions (3)
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BSD mandoc

NAME

getenv putenv setenv unsetenv - environment variable functions

SYNOPSIS

Fd #include <stdlib.h> Ft char * Fn getenv const char *name Ft int Fn setenv const char *name const char *value int overwrite Ft int Fn putenv const char *string Ft void Fn unsetenv const char *name

DESCRIPTION

These functions set, unset and fetch environment variables from the host environment list For compatibility with differing environment conventions, the given arguments name and value may be appended and prepended, respectively, with an equal sign ``= ''

The Fn getenv function obtains the current value of the environment variable, name If the variable name is not in the current environment , a null pointer is returned.

The Fn setenv function inserts or resets the environment variable name in the current environment list. If the variable name does not exist in the list, it is inserted with the given value. If the variable does exist, the argument overwrite is tested; if overwrite is zero, the variable is not reset, otherwise it is reset to the given value

The Fn putenv function takes an argument of the form ``name=value'' and is equivalent to:

setenv(name, value, 1);

The Fn unsetenv function deletes all instances of the variable name pointed to by Fa name from the list.

RETURN VALUES

The functions Fn setenv and Fn putenv return zero if successful; otherwise the global variable errno is set to indicate the error and a -1 is returned.

ERRORS

Bq Er ENOMEM: The function Fn setenv or Fn putenv failed because they were unable to allocate memory for the environment.

STANDARDS

The Fn getenv function conforms to St -ansiC .

HISTORY

The functions Fn setenv and Fn unsetenv appeared in AT&T System v7 . The Fn putenv function appeared in BSD 4.3 Reno

This document was created by man2html, using the manual pages.
Time: 19:41:56 GMT, December 25, 2022