code: 9ferno

ref: b39057dffedac61fd6c028908a9aaadf4426b446
dir: /man/3/env/

.TH ENV 3
.SH NAME
env \- environment device
.SH SYNOPSIS
.nf
.B bind #e /env

.BI /env/ name
.fi
.SH DESCRIPTION
The environment device serves a one-level directory giving access to environment variables
and their values.
It is conventionally bound to
.BR /env .
The value of an environment variable 
.I name
may be obtained by reading the file
.BI /env/ name.
If the file does not exist, the variable is unset and has the value nil. The
maximum length of a variable name is 127 bytes.
.PP
New environment variables are set by creating the corresponding file
in
.B /env
and writing the required value to that file. Similarly environment variables are destroyed (unset) by
removing the corresponding file.
.PP
Processes sharing an `environment group' see the same files and contents;
changes made by one process are seen by the others.
A process can insulate itself from further changes using the
.L FORKENV
option to
.IR sys-pctl (2),
which creates a new environment group that is a copy of the old,
but further changes in each are independent.
A new empty environment group is created by the
.L NEWENV
option to
.IR sys-pctl (2).
.SH SOURCE
.B /os/port/devenv.c
.br
.B /emu/port/devenv.c
.SH SEE ALSO
.IR env (1),
.IR sh (1),
.IR env (2),
.IR sys-pctl (2)