NixOS (postfix) places mail in /var/spool/mail but $MAIL points to /var/mail/*

[bjornfor]

Workaround, run your MUA like this:

MAIL=/var/spool/mail/$USER mutt

I tried locating the base path for $MAIL. Grepping nixpkgs yields nothing. Grepping bash sources indicates that there is a ./configure variable called bash_cv_mail_dir that can be set. The weird part is that this variable gets initialized like this:

{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for default mail directory" >&5
$as_echo_n "checking for default mail directory... " >&6; }
if ${bash_cv_mail_dir+:} false; then :
  $as_echo_n "(cached) " >&6
else
  if test -d /var/mail; then
   bash_cv_mail_dir=/var/mail
 elif test -d /var/spool/mail; then
   bash_cv_mail_dir=/var/spool/mail
 elif test -d /usr/mail; then
   bash_cv_mail_dir=/usr/mail
 elif test -d /usr/spool/mail; then
   bash_cv_mail_dir=/usr/spool/mail
 else
   bash_cv_mail_dir=unknown
 fi

fi

So I would actually expect it to be set to "unknown", given that hydra (and I) build packages in chroots.

Anyway, I see three ways to solve this:

• build bash with MAIL=/var/spool/mail
• add /var/mail -> /var/spool/mail symlink in NixOS
• change NixOS/postfix mail path from /var/spool/mail to /var/mail

Data point: FHS actually recommends /var/mail:
http://www.pathname.com/fhs/pub/fhs-2.3.html#VARMAILUSERMAILBOXFILES

[peti]

I'm not sure what you mean by "$MAIL points to /var/mail". $MAIL is undefined on my NixOS system. No variable in my declare -p environment mentions neither /var/mail nor /var/spool/mail. To me, it looks more likely that mutt has that default path compiled in; I don't believe bash has anything to do with that.

[bjornfor]

What? You don't have $MAIL environment variable at all?

$ echo $MAIL
/var/mail/bfo

AFAICS, it is bash that has the compiled in $MAIL pointing to /var/mail/*.

After thinking about this for a bit, I guess the /var/mail -> /var/spool/mail symlink is the best option. Then we are the most compatible and don't have to rebuild anything.

[peti]

Resolved by #8206.