Manpage of SETENV

SETENV

Section: Linux Programmer's Manual (3)
Updated: 2016-03-15
Index
 

NAME

setenv - change or add an environment variable  

SYNOPSIS

#include <stdlib.h>int setenv(const char *name, const char *value, int overwrite);int unsetenv(const char *name);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

setenv(), unsetenv():

_POSIX_C_SOURCE >= 200112L
    || /* Glibc versions <= 2.19: */ _BSD_SOURCE
 

DESCRIPTION

The setenv() function adds the variable nameto the environment with the value value, if namedoes not already exist. If namedoes exist in the environment, then its value is changed to valueif overwriteis nonzero; if overwriteis zero, then the value of nameis not changed (and setenv() returns a success status). This function makes copies of the strings pointed to by nameand value(by contrast with putenv(3)).

The unsetenv() function deletes the variable namefrom the environment. If namedoes not exist in the environment, then the function succeeds, and the environment is unchanged.  

RETURN VALUE

The setenv() function returns zero on success, or -1 on error, with errnoset to indicate the cause of the error.

The unsetenv() function returns zero on success, or -1 on error, with errnoset to indicate the cause of the error.  

ERRORS

EINVAL
nameis NULL, points to a string of length 0, or contains an aq=aq character.
ENOMEM
Insufficient memory to add a new variable to the environment.
 

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).
InterfaceAttributeValue
setenv(), unsetenv() Thread safetyMT-Unsafe const:env
 

CONFORMING TO

POSIX.1-2001, POSIX.1-2008, 4.3BSD.  

NOTES

POSIX.1 does not require setenv() or unsetenv() to be reentrant.

Prior to glibc 2.2.2, unsetenv() was prototyped as returning void; more recent glibc versions follow the POSIX.1-compliant prototype shown in the SYNOPSIS.  

BUGS

POSIX.1 specifies that if namecontains an aq=aq character, then setenv() should fail with the error EINVAL; however, versions of glibc before 2.3.4 allowed an aq=aq sign in name.  

SEE ALSO

clearenv(3), getenv(3), putenv(3), environ(7)


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
ATTRIBUTES
CONFORMING TO
NOTES
BUGS
SEE ALSO

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