当我尝试安装 postfix 时，收到以下错误：
root@myvps:~# apt install postfix
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
postfix-sqlite
Suggested packages:
postfix-mysql postfix-pgsql postfix-ldap postfix-pcre postfix-lmdb sasl2-bin
dovecot-common resolvconf postfix-cdb ufw postfix-doc
The following NEW packages will be installed:
postfix postfix-sqlite
0 upgraded, 2 newly installed, 0 to remove and 0 not upgraded.
Need to get 0 B/1,755 kB of archives.
After this operation, 4,378 kB of additional disk space will be used.
Do you want to continue? [Y/n] Y
Preconfiguring packages ...
Selecting previously unselected package postfix-sqlite.
(Reading database ... 66632 files and directories currently installed.)
Preparing to unpack .../postfix-sqlite_3.1.8-0+deb9u1_amd64.deb ...
Unpacking postfix-sqlite (3.1.8-0+deb9u1) ...
Selecting previously unselected package postfix.
Preparing to unpack .../postfix_3.1.8-0+deb9u1_amd64.deb ...
Unpacking postfix (3.1.8-0+deb9u1) ...
Processing triggers for systemd (232-25+deb9u2) ...
Processing triggers for man-db (2.7.6.1-2) ...
Setting up postfix-sqlite (3.1.8-0+deb9u1) ...
grep: /etc/postfix/dynamicmaps.cf: No such file or directory
Adding sqlite map entry to /etc/postfix/dynamicmaps.cf
Processing triggers for rsyslog (8.24.0-1) ...
Setting up postfix (3.1.8-0+deb9u1) ...
Created symlink /etc/systemd/system/multi-user.target.wants/postfix.service → /lib/systemd/system/postfix.service.
Adding group `postdrop' (GID 118) ...
Done.
setting myhostname: myvps
setting alias maps
setting alias database
setting myorigin
setting destinations: $myhostname, example.com, myvps, localhost.localdomain, localhost
setting relayhost:
setting mynetworks: 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
setting mailbox_command
setting mailbox_size_limit: 0
setting recipient_delimiter: +
setting inet_interfaces: all
setting inet_protocols: all
Postfix (main.cf) is now set up with a default configuration. If you need to
make changes, edit /etc/postfix/main.cf (and others) as needed. To view
Postfix configuration values, see postconf(1).
After modifying main.cf, be sure to run 'service postfix reload'.
Running newaliases
newaliases: fatal: scan_dir_push: open directory /etc/postfix/dynamicmaps.cf.d: Permission denied
dpkg: error processing package postfix (--configure):
subprocess installed post-installation script returned error exit status 75
Processing triggers for systemd (232-25+deb9u2) ...
Processing triggers for rsyslog (8.24.0-1) ...
Errors were encountered while processing:
postfix
needrestart is being skipped since dpkg has failed
E: Sub-process /usr/bin/dpkg returned an error code (1)
为什么当我尝试安装 postfix 时 dpkg 失败？
的输出ls -ld /etc/postfix/dynamicmaps.cf.d：
ls: cannot access '/etc/postfix/dynamicmaps.cf.d': No such file or directory