At which stage in the Emacs startup sequence does the $HOST
environment variable become available to Emacs?
reddit / emacs

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vfclists · 2022-09-26 10:02

I've got an environment variable called $HOST and it seems that Emacs
doesn't read it early enough. It usually isn't available during the
execution of `init.el`

It s present in the environment frm which I run Emacs.

`(getenv "HOST")` returns a blank and it is annoying as my `custom-
file` includes the `USER` and `HOST` variables so I can use the same
configuration on different systems without clobbering the `custom.el`.

Once Emacs fully loads it is available and `(getenv "HOST")` works
fine.

Is there some reason Emacs behaves this way for this particular
variable?

**SOLVED**

I checked my `.profile` and realized that in this instance the config
file which creates the `HOST` variable was not being `source`'d, so
I've fixed it in this instance.

The problem dates back some years ago when the default Debian
environment was not creating a variable I needed so I had to add

`export HOST=$(hostname)`

to my `.profile` to ensure it would be available to GUI programs.

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susanne-o · 2022-09-26 11:19

I'd suspect something trivial like "printer cable not connected" when
the printer doesn't work.

is HOST exported to child processes in your shell?  i.e. is HOST in
initial-environment on your system?  you can check that by entering
the debugger in your init.el



add (debug) to your init.el and a `--debug-init` argument on the
command line.


https://www.gnu.org/software/emacs/manual/html_node/elisp/System-
Environment.html

https://www.gnu.org/software/emacs/manual/html_node/elisp/Explicit-
Debug.html

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seishuuu · 2022-09-26 11:25

while this does not answer your initial question about the behavior, I
use `(system-name)` and `(system-type)` to do such configuration.

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arthurno1 · 2022-09-26 12:10

As suggested, by others (system-name) is probably what you are looking
for.

C-h f system-name RET
>
> system-name is a built-in function in ‘C source code’.
>
> (system-name)
>
> Return the host name of the machine you are running on, as a string.
>
>   Probably introduced at or before Emacs version 19.23.

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vfclists · 2022-09-26 12:24

I think I will switch to `(system-name)` for the future. BTW `system-
type` is a variable not a function.

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vfclists · 2022-09-26 12:24

I checked it and realized that in this instance the config file which
creates the `HOST` variable was not being `source`'d, so I've fixed it
in this instance.

The problem dates back some years ago when the default Debian
environment was not creating a variable I needed so I had to add

`export HOST=$(hostname)`

to my `.profile` to ensure it would be available to GUI programs.

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susanne-o · 2022-09-26 12:31

see, printer was simply not plugged in ;-)  thanks for the update.

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yurikhan · 2022-09-26 14:51

I seem to remember `export VAR=VALUE` is a bashism so can’t portably
be used in `.profile` which is a POSIX-standardized file. You’re
supposed to say `VAR=VALUE` and `export VAR` separately.

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DrPiwi · 2022-09-26 15:07

Why not use the standard `$HOSTNAME` variable that is set
automatically?

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mmaug · 2022-09-26 17:42

`VAR=VAL; export VAR`
should be portable

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vfclists · 2022-09-26 19:10

I set it some years ago. I can't remember the reason why but I think
back then HOSTNAME was not appropriate or conflicted with something
else.