GETENV(3) Library Functions Manual GETENV(3)NAME
getenv - value for environment name
Getenv searches the environment list (see environ(5)) for a string of the form name=value and returns value if such a string is present,
otherwise 0 (NULL).
SEE ALSO environ(5), exec(2)GETENV(3)
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getenv(3) Library Functions Manual getenv(3)Name
getenv, setenv, unsetenv - manipulate environment variables
setenv(name, value, overwrite)
char *name, value;
The subroutine searches the environment list for a string of the form name = value and returns a pointer to the string value if such a
string is present, otherwise returns the value 0 (NULL). For further information, see
The subroutine searches the environment list in the same manner as If the string name is not found, a string of the form name=value is
added to the environment. If it is found, and overwrite is non-zero, its value is changed to value. The subroutine returns 0 on success
and -1 on failure, where failure is caused by an inability to allocate space for the environment.
The subroutine removes all occurrences of the string name from the environment. There is no library provision for completely removing the
current environment. It is suggested that the following code be used to do so.
static char *envinit;
extern char **environ;
environ = envinit;
All of these routines permit, but do not require, a trailing equals sign (=) on name or a leading equals sign on value.
See Alsocsh(1), sh(1), execve(2), putenv(3), environ(7)getenv(3)