getenv(3) Library Functions Manual getenv(3)Name
getenv, setenv, unsetenv - manipulate environment variables
Syntax
char *getenv(name)
char *name;
setenv(name, value, overwrite)
char *name, value;
int overwrite;
void unsetenv(name)
char *name;
Description
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 Alsocsh(1), sh(1), execve(2), putenv(3), environ(7)getenv(3)
Check Out this Related Man Page
GETENV(3) Linux Programmer's Manual GETENV(3)NAME
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 3.25 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
GNU 2008-03-17 GETENV(3)
Hi!
How-to get the environment variables in GNU.
getenv() only fetches the ones that you can find under export (not the ones under declare)...
best regars .David (2 Replies)
I have been resently working on some ksh script. One of the line in the file writes:
.. /etc/.environment dev_env
I can not understand what this mean, all I know is .environment is unix system environment file. Is ".." a command? If some one can give me some clue where can I find information... (7 Replies)
Hi,
I do have a code as follows:
function deHex {
if ]; then
deHexDate=${1:1:$2}
fi
}
The description given for the above code is as follows:
# description: removes leading zero so value will not be recognized as hex
# usage: deHex <value_parameter> <value_input_length>
... (0 Replies)
There is a function in Perl named PerlEnv_getenv() which is equivalent to getenv() in C. It invokes the environment variable. It uses the library the library perlclib.How to define this library and use the Perl function? (3 Replies)
Hi,
Actually I am facing one issue while using the getenv() in the C/C++ program.
I want to take the file path from environment variables and if am not defining the environment path, its showing the message like this…!
Memory fault(coredump)
Actually I want to handle the error ,... (6 Replies)
Hello,
This is my code:
i'd like to like to add getenv("MYLIB") in the first case of my buffer inside of '1' , should i do the cast ? and how please ?
Thank you. (1 Reply)
Hi,
I am trying to remove leading and trailing spaces from a file using awk but somehow I have not been able to do it.
Here is the data that I want to trim.
07/12/2017 15:55:00 |entinfdev |AD ping Time ms | .474| 1.41| .581|green |flat... (9 Replies)