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setenv(3) [ultrix man page]

getenv(3)						     Library Functions Manual							 getenv(3)

       getenv, setenv, unsetenv  - manipulate environment variables

       char *getenv(name)
       char *name;

       setenv(name, value, overwrite)
       char *name, value;
       int overwrite;

       void unsetenv(name)
       char *name;

       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[1];
       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 Also
	csh(1), sh(1), execve(2), putenv(3), environ(7)


Check Out this Related Man Page

GETENV(3)						     Linux Programmer's Manual							 GETENV(3)

getenv - get an environment variable SYNOPSIS
#include <stdlib.h> char *getenv(const char *name); DESCRIPTION
The getenv() function searches the environment list to find the environment variable name, and returns a pointer to the corresponding value string. RETURN VALUE
The getenv() function returns a pointer to the value in the environment, or NULL if there is no match. CONFORMING TO
SVr4, POSIX.1-2001, 4.3BSD, C89, C99. NOTES
The strings in the environment list are of the form name=value. As typically implemented, getenv() returns a pointer to a string within the environment list. The caller must take care not to modify this string, since that would change the environment of the process. The implementation of getenv() is not required to be reentrant. The string pointed to by the return value of getenv() may be statically allocated, and can be modified by a subsequent call to getenv(), putenv(3), setenv(3), or unsetenv(3). SEE ALSO
clearenv(3), putenv(3), setenv(3), unsetenv(3), environ(7) COLOPHON
This page is part of release 3.27 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at GNU
2008-03-17 GETENV(3)
Man Page

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