Install cmupdate "inc/cpcheck.inc: line 681: postconf: command not found"

postconf command belows to postfix yum package so if that command is missing, it means you somehow removed postfix MTA mail server !

what's output for this command to trace yum history commands for postfix

Code (Text):

yum history info postfix

for posting code or output from commands to keep the formatting, you might want to use CODE tags for code How to use forum BBCODE code tags

 

very first yum history info postfix transaction id = 41 shows that you using mysql 5.7 (not centmin mod default) so when you yum removed mysql 5.7, you also removed postfix MTA mailserver as it's a dependency /linked - so you wiped your Postfix mailserver and hence no postconf command and no functioning mail server for outbound emails either !

so you changed from Centmin Mod default MariaDB 10 to Oracle MySQL 5.7 ? but that change wiped your postfix MTA mailserver ! and also removed pure-ftpd FTP server too !! You've screwed up your server ! Without knowing what else you may have messed up, best to just backup all your data files/databases and restore on a fresh CentOS 7 + fresh Centmin Mod 123.09beta01 installation using the default MariaDB 10.3 MySQL server instead.

Code (Text):

yum history info postfix
Loaded plugins: fastestmirror, priorities, versionlock
Transaction ID : 41
Begin time     : Thu May 23 20:17:14 2019
Begin rpmdb    : 814:2e56b4a5444c7b09dd8de49d10740ece0fb440fa
End time       :            20:17:20 2019 (6 seconds)
End rpmdb      : 803:b0c351a4aa113cb26197dd5698ae874aa1b769ce
User           : root <root>
Return-Code    : Success
Command Line   : remove mysql-community-client.x86_64 mysql-community-common.x86_64 mysql-community-devel.x86_64 mysql-community-libs.x86_64 mysql-community-libs-compat.x86_64 mysql-community-server.x86_64 mysql57-community-release.noarch
Transaction performed with:
    Installed     rpm-4.11.3-35.el7.x86_64                      @anaconda
    Installed     yum-3.4.3-161.el7.centos.noarch               @anaconda
    Installed     yum-plugin-fastestmirror-1.1.31-50.el7.noarch @anaconda
Packages Altered:
    Erase mysql-community-common-5.7.26-1.el7.x86_64      @mysql57-community
    Erase mysql-community-libs-5.7.26-1.el7.x86_64        @mysql57-community
    Erase mysql-community-libs-compat-5.7.26-1.el7.x86_64 @mysql57-community
    Erase mysql57-community-release-el7-11.noarch         @/mysql57-community-release-el7-11.noarch
    Erase mytop-1.7-10.b737f60.el7.noarch                 @epel
    Erase net-snmp-1:5.7.2-37.el7.x86_64                  @base
    Erase net-snmp-devel-1:5.7.2-37.el7.x86_64            @base
    Erase perl-DBD-MySQL-4.023-6.el7.x86_64               @base
    Erase postfix-2:2.10.1-7.el7.x86_64                   @anaconda
    Erase postfix-perl-scripts-2:2.10.1-7.el7.x86_64      @base
    Erase pure-ftpd-1.0.47-2.el7.x86_64                   @epel
Scriptlet output:
   1 warning: /etc/postfix/main.cf saved as /etc/postfix/main.cf.rpmsave
   2 warning: /etc/pure-ftpd/pure-ftpd.conf saved as /etc/pure-ftpd/pure-ftpd.conf.rpmsave

from that transaction id = 41 i see the yum command that you ran was

Code (Text):

yum remove mysql-community-client.x86_64 mysql-community-common.x86_64 mysql-community-devel.x86_64 mysql-community-libs.x86_64 mysql-community-libs-compat.x86_64 mysql-community-server.x86_64 mysql57-community-release.noarch

 

no i meant, that yum remove command was run on your system and yum history recorded that the command was ran on Thu May 23 20:17:14 2019 server time, that is why you have postconf issues as your yum remove command ran on Thu May 23 20:17:14 2019 server time, removed Oracle MySQL 5.7 yum packages and it's dependency packages for postfix and pure-ftpd and other yum packages messing up your server. Centmin Mod does not install Oracle MySQL 5.7 so you or someone with access to your server installed it after Centmin Mod was installed.

Code (Text):

yum history info postfix
Loaded plugins: fastestmirror, priorities, versionlock
Transaction ID : 41
Begin time     : Thu May 23 20:17:14 2019
Begin rpmdb    : 814:2e56b4a5444c7b09dd8de49d10740ece0fb440fa
End time       :            20:17:20 2019 (6 seconds)
End rpmdb      : 803:b0c351a4aa113cb26197dd5698ae874aa1

you can find when Oracle MySQL 5.7 was installed via yum history info command again

Code (Text):

yum history info mysql-community-common mysql57-community-release mysql-community-libs mysql-community-libs-compat

In that case yes you're messed up your Centmin Mod install as Centmin Mod needs virgin CentOS install without any conflicting packages like Oracle MySQL 5.7.

Without knowing what else you may have messed up, best to just backup all your data files/databases and restore on a fresh CentOS 7 + fresh Centmin Mod 123.09beta01 installation using the default MariaDB 10.3 MySQL server instead.