ENV(3) ENV(3)
NAME
env - environment variables
SYNOPSIS
bind #e /env
/env/var1
/env/var2
...
DESCRIPTION
The env device serves a one-level directory containing files
with arbitrary names and contents. The intention is that
the file name is the name of an environment variable (see
rc(1)), and the content is the variable's current value.
When a fork(2) system call creates a new process, both the
parent and the child continue to see exactly the same files
in the env device: changes made in either process can be
noticed by the other. In contrast, an rfork system call
with the RFENVG bit set (see fork(2)) causes a split: ini-
tially both process groups see the same environment files,
but any changes made in one process group cannot be noticed
by the other. An rfork with RFCENVG splits and then clears
the environment.
The special global environment #ec contains kernel configu-
ration variables, such as those set in plan9.ini(8). All
processes see the same #ec; its contents are writable only
by the host owner. [XXX actually everything is world writ-
able; that's a mistake.]
SEE ALSO
rc(1), fork(2), #c/reboot in cons(3), plan9.ini(8)
SOURCE
/sys/src/9/port/devenv.c
BUGS
A write starting at an offset after the current extent of a
file yields an error instead of zero filling.
Page 1 Plan 9 (printed 12/21/24)